Osteohistology and Growth of Edmontosaurus and Assessment of Life History Changes in Hadrosaurid Dinosaurs

Mateusz Wosik

A thesis submitted in conformity with the requirements for the degree of Doctor of Philosophy Department of Ecology and Evolutionary Biology University of Toronto

Mateusz Wosik

Doctor of Philosophy

Department of Ecology and Evolutionary Biology University of Toronto

2018 Abstract

Data on the life history of an organism provides an important window into its biology, ecology, and evolution but has been challenging to obtain for the extinct due to limitations of fossil sampling and the inability for direct observation. The recent utilization of osteohistology, which is the study of the internal bone microstructure, has revolutionized paleontological research and permitted quantitative assessment of numerous life history aspects in extinct organisms.

Hadrosaurid dinosaurs, the dominant large-bodied terrestrial herbivores in most Late Cretaceous ecosystems, have an exceptional fossil record consisting of over 60 species and multiple ontogenetic bonebeds making them an ideal clade on which to conduct life history studies. The objectives of this thesis were to integrate new data and methods to investigate ontogenetic growth and test life history strategies in hadrosaurid populations from the Late Cretaceous of

North America, with a particular emphasis on the integration of osteohistological methods with limb growth and size frequency distributions for inferring biomechanical gait shifts, growth and population dynamics, and mass death preservational patterns. The results in this thesis demonstrate that the proportions of the appendicular skeleton of hadrosaurid dinosaurs did not undergo allometric growth through ontogeny and provide no compelling evidence to support the

ii previously hypothesized ontogenetic gait shift in hadrosaurids. Size-frequency distributions underestimate age and overestimate growth rates. However, when paired with osteohistology, the data reveal that juvenile hadrosaurids segregated from adults providing essential insight into the population dynamics of these animals. The comprehensive growth curve analysis indicates that hadrosaurids exhibited a similar growth trajectory regardless of a wide ranging asymptotic body size (~3000–6000 kg) suggesting that the clade as a whole inherited a similar growth strategy attaining adult size within 7–9 years. This thesis strongly recommends both the independent assessment and the integration of allometric scaling, size-frequency distributions, and osteohistology to provide more accurate and precise paleobiological interpretations of life history characteristics.

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A Day in the Life of Edmontosaurus. Edmontosaurus nestlings, similar to many other duck- billed dinosaurs, segregated from adults likely forming their own independent groups. Here, one of these groups encounters the skeletal remains of an adult. The illustration of the Sandstone Basin locality from northeastern Montana is split into a present field photograph (left) and interpretation of the paleoenvironment (right) to demonstrate the significant environmental changes over 66 million years.

I dedicate this thesis to my son, Otter Emmerich Wosik.

Your first year of life has known nothing but me working on this thesis. With it behind us, know that I will always be there for you. Now let’s enjoy the adventures our lives have in store for us!

Acknowledgments

So many people have helped me along the way during this work that I sincerely hope that I do not forget anyone. To start, I’d like to thank:

…My advisor and mentor, Dr. David C. Evans. When I entered the lab, I was the definition of green. Full of wild ideas, no focus, and chasing rabbit holes. If you must know, I did indeed read large portions of that Zar biostats book but still have no idea how to reasonably comprehend quantile-quantile plots. During my PhD, you molded my mind to be more than just a scientist by providing me with a wide array of opportunities to develop to various skillsets. My favorite was when you let me literally shovel dirt for hours, and on more than one occasion (true fact, I love shoveling me some dirt). But more seriously, you taught me the patience to fully analyze each situation and the perseverance of commitment. You were supportive when life took unexpected detours, and at times, felt isolating. I know I wasn’t the easiest of students and occasionally tested your nerves, but I truly hope that one day, I can follow your lead and pass on the wisdom you shared with me.

…My supervisory committee members, Dr. Deborah McLennan and Dr. Robert Reisz, for making me think beyond the scope of this work by relating it to the modern world. Your constructive feedback, and the occasional complete rewrite of sections, significantly shaped this work from its infancy. An honorable mention to the science related comic strips that provided much needed self-esteem boosts when data and results had a mind of their own.

…My appraisal and defense committee members, Dr. Anusuya Chinsamy-Turan, Dr. Marc

LaFlamme, Dr. Mary Silcox, and Dr. Bob Murphy for critically testing my current knowledge and stretching it beyond lengths I could have never imagined.

…My undergraduate professors that steered me towards zoology and ecology, in particular Dr.

Kyle Bennett, Dr. Chris Petersen, Dr. Paul Arriola, and especially Dr. Merrilee Guenther, who offered me my first opportunity in paleontology as an undergraduate research assistant and single handedly saved me from the dark side of molecular biology.

…The ROM paleo staff, Peter Fenton, Brian Iwama, Ian Morrison, Dave Rudkin, Kevin

Seymour, and Shino Sugimoto, I cannot thank you enough. Beyond all the time that you invested to teach me new skills, I want you to know that your continued support and words of encouragement did not go unnoticed, and at times, had more of a positive impact than I let up.

…All of my ROM labmates, past and present, with special mention to Kentaro Chiba, Aaron

Leblanc, Cary Woodruff, and Danielle Dufault for having the patience to answer all my questions, teaching me all I know about histology, and being an ear when I needed to get things off my chest. From noodles to beers, I’ll always cherish the memories of growing up with you.

…The entire Badlands National Park staff for being at the core of the two best summers of my life. I arrived in a mysterious land not knowing a single soul, but left with a heavy heart and countless life-long relationships. To the staff and volunteers that taught me all I know about outreach: Rachel Benton, Megan Cherry, Connie Wolf, Paul, Larry, Cindy, Chuck, and Sandra.

To the friends that made every laugh count: Levi Darwin Moxness, Dakota McCoy, Ed Welsh,

Nick Famoso, Sarah Nevison, Danny Redding, Evan Doughty, Ian Knoerl, Clint Boyd, Mindy

Householder, Katie Johnston, and so many more. And most importantly, Aaron Kaye and Ellen

Starck. Without your encouragement and support, I may have never considered continuing my education. For that alone, have a proper liquid courage and a chilled Mountain Dew, on me.

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I am also very grateful for the financial support during my time at the University of Toronto. A five year University of Toronto Fellowship, four one-year Joseph Bazylewicz Fellowships, as well as numerous departmental-level awards and travel funds made this work possible.

To my dear friends: Sungsik ‘Kevin’ Kong, Tomas Frecka, Eva Rodinova, Peter Vlcek,

Magdalena Salatova, Laurel Duquette, Eric Owens, Mike Swift, and especially Sarah Steele. I am going to bloody damn miss you all. From countless laughs to tearful goodbyes, you made living in another country that much easier because I knew I could rely on each of you for anything. Although we may be friends by blood, you all are my family by heart.

To my in-laws, Dennis and Cynthia Yeider. I will always remember that before I could finish asking you for your permission to marry your daughter, you interjected to say ‘absolutely yes.’

From that moment, I knew I was being welcomed into an incredible family that has shown me nothing but endless support ever since, especially during my Ph.D. studies.

To my dog, Moose. Thank you for putting up with my near-criminal practice talks and keeping me in check by giving your infamous cue when it was time to go to bed.

To my wife, Lindsey Elizabeth Yeider, I thank you for your endless love and support. Through stratospheric highs and earth shattering lows, you have been the single constant in my life.

Whenever I needed a bit of a nudge, you jumped right into the water with me. If I ever felt knocked down, you dug a 10 foot hole to show me I was nowhere near the bottom. I am truly blessed knowing that I married my best friend. When we moved to Toronto nearly five years ago, I never imagined that we would be concluding this chapter of our lives as a family. Let’s never forget that ‘adventure is out there’ and now we have a ‘zoo’ to tag along with us.

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And lastly, to my parents, Maria and Stanisław Wosik. Przede wszystkim nauczyliście mnie wartośći ciężkiej pracy i dopilnowywania, bym kończył to, co zacząłem. Chociaż nigdy nie będę w stanie odwdzięczyć się za Wasze bezinteresowne poświęcenie w czasie, kiedy wyemigrowaliśmy do Stanów Zjednoczonych, zapewniliście mi tą możliwość, która mam nadzieję, czyni was dumnymi. Z głebi serca, dziękuję Wam serdecznie.

Above all, you taught me the value of hard work and making sure to finish what I started.

Although I will never be able to repay the selfless sacrifices the both of you endured when we immigrated to the United States, you provided me with this opportunity that I hope makes you proud. From the bottom of my heart, thank you.

Table of Contents

Acknowledgments ...... vi

Table of Contents ...... x

List of Tables ...... xiv

List of Figures ...... xv

List of Supplementary Tables ...... xvii

List of Supplementary Figures ...... xviii

List of Appendices ...... xix

List of Institutional Abbreviations ...... xx

Background and Context ...... xxii

Chapter 1 A nestling-sized skeleton of Edmontosaurus (Ornithischia, Hadrosauridae) from the Hell Creek Formation of northeastern Montana, U.S.A., with an analysis of ontogenetic limb allometry ...... 1

1.1 Abstract ...... 2

1.2 Introduction ...... 3

1.3 Geological Setting ...... 4

1.4 Materials and Methods ...... 5

1.4.1 Measurements ...... 6

1.4.2 Regression Analyses ...... 6

1.4.3 Body Mass Estimation ...... 8

1.5 Systematic Paleontology ...... 8

1.6 Description and Ontogenetic Comparison ...... 9

1.6.1 Axial Skeleton ...... 9

1.6.2 Pectoral Girdle ...... 11

1.6.3 Pelvic Girdle ...... 12

1.6.4 Hindlimb ...... 14

1.6.5 Taxonomic Identification ...... 16

1.7 Results ...... 17

1.7.1 Bivariate Analyses ...... 17

1.7.2 Estimation of Forelimb Lengths and Body Mass in UCMP 128181 ...... 20

1.8 Discussion ...... 21

1.8.1 Limb Allometry of Edmontosaurus and Gait Change in Hadrosaurs ...... 23

1.9 Conclusion ...... 28

1.10 Acknowledgments...... 28

1.11 Funding ...... 29

1.12 Tables ...... 30

1.13 Figures and Figure Captions ...... 41

1.14 Supplementary Tables ...... 59

Chapter 2 Life history and paleoecology of hadrosaurid dinosaurs from the Dinosaur Park Formation of Alberta, Canada, with implications for population structure ...... 67

2.1 Abstract ...... 68

2.2 Introduction ...... 69

2.3 Materials and Methods ...... 71

2.3.1 Regression Analyses ...... 72

2.3.2 Size-Frequency Distributions ...... 73

2.3.3 Osteohistology ...... 74

2.3.4 Age Determination and Growth Modeling ...... 76

2.4 Results ...... 78

2.4.1 Regression Analyses ...... 79

2.4.2 Size-Frequency Distributions ...... 80

2.4.3 Osteohistology ...... 81

2.4.4 Age Determination and Growth Modeling ...... 84

2.5 Discussion ...... 86

2.5.1 Comparison with Other Hadrosaurid Taxa ...... 90

2.5.2 Socioecology, Population Structure, and Seasonal Preservation Patterns .....91

2.6 Conclusion ...... 99

2.7 Acknowledgments...... 99

2.8 Tables ...... 101

2.9 Figures and Figure Captions ...... 105

2.10 Supplementary Tables ...... 125

2.11 Supplementary Figures ...... 141

Chapter 3 Life history of Edmontosaurus annectens (Ornithischia: Hadrosauridae) from the Late Cretaceous (Maastrichtian) Ruth Mason Dinosaur Quarry, South Dakota, United States ...... 147

3.1 Abstract ...... 148

3.2 Introduction ...... 149

3.3 Geological Setting ...... 152

3.4 Materials and Methods ...... 153

3.4.1 Regression Analyses ...... 154

3.4.2 Size-Frequency Distributions ...... 154

3.4.3 Osteohistology ...... 155

3.4.4 Age Determination and Growth Modeling ...... 157

3.5 Results ...... 159

3.5.1 Regression Analyses ...... 160

3.5.2 Size-Frequency Distributions ...... 161

3.5.3 Osteohistology ...... 164

3.5.4 Age Determination and Growth Modeling ...... 176 xii

3.6 Discussion ...... 178

3.6.1 Population Dynamics of Edmontosaurus ...... 182

3.6.2 Reevaluating the Effects of Environmental Stressors on Osteohistology in Edmontosaurus ...... 184

3.6.3 Histologically Assessing the Validity of Anatotitan ...... 186

3.7 Conclusion ...... 189

3.8 Acknowledgments...... 189

3.9 Tables ...... 191

3.10 Figures and Figure Captions ...... 195

3.11 Supplementary Tables ...... 223

References ...... 229

Appendices ...... 251

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List of Tables

Table 1-1. UCMP 128181 vertebral column measurements (mm) ...... 30

Table 1-2. UCMP 128181 appendicular skeleton measurements (mm) ...... 32

Table 1-3. Standard Major Axis (SMA) results from the bivariate morphometric analyses of appendicular element variables against total femur length (x) ...... 34

Table 1-4. Standard Major Axis (SMA) results from the bivariate morphometric analyses of circumference, combined limb length, and intra-bone comparisons ...... 37

Table 1-5. Estimated OLS regression values for UCMP 128181 from comparisons using femur length as the standard variable ...... 39

Table 1-6. Total femur length measurements (mm) of hadrosaurid ontogenetic stages ...... 40

Table 2-1. Summary of parameter values and results for averaged age retrocalculation growth models ...... 101

Table 3-1. List of Edmontosaurus specimens osteohistologically sampled and examined for this study and their corresponding measurement values ...... 191

Table 3-2. Summary of Edmontosaurus body mass estimates of associated skeletons ...... 193

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List of Figures

Figure 1-1. Sandstone Basin UCMP locality V80092 ...... 41

Figure 1-2. Main block of UCMP 128181 Edmontosaurus cf. annectens skeleton ...... 43

Figure 1-3. Counterpart of UCMP 128181 Edmontosaurus cf. annectens skeleton ...... 45

Figure 1-4. Anterior half of UCMP 128181 main block...... 47

Figure 1-5. Tail impressions of UCMP 128181 ...... 49

Figure 1-6. Pelvic girdles of UCMP 128181 ...... 51

Figure 1-7. Major hind limb elements of UCMP 128181 ...... 53

Figure 1-8. Right metatarsals of UCMP 128181 main block ...... 55

Figure 1-9. Bivariate allometric results. SMA regressions for a variety of appendicular measurements ...... 57

Figure 2-1. Geographic map distinguishing hadrosaurid taxa between the Dinosaur Park Formation (DPF) of Alberta, Canada, and the Two Medicine Formation (TMF) of Montana, USA...... 105

Figure 2-2. Combined size-frequency distributions of hadrosaurids from the Dinosaur Park Formation (DPF) of Alberta, Canada ...... 107

Figure 2-3. Size-frequency distributions of hadrosaurid humeri, femora, and tibiae from the Dinosaur Park Formation of Alberta, Canada...... 109

Figure 2-4. Osteohistology of nestling through subadult hadrosaurid tibiae from the Dinosaur Park Formation of Alberta, Canada under plain-polarized and cross-polarized light microscopy ...... 111

Figure 2-5. Osteohistology of adult hadrosaurid tibiae from the Dinosaur Park Formation of Alberta, Canada...... 113

Figure 2-6. Summary of section stacking of tibiae ...... 115

Figure 2-7. Hadrosaurid growth curves ...... 117

Figure 2-8. Size-frequency distribution of tibial minimum diaphyseal circumference integrated with osteohistology ...... 119

Figure 2-9. Comparative summary of size-frequency distributions across all individual bone elements ...... 121

Figure 2-10. Density comparison of long bone and tracksite size distributions of hadrosaurid bonebeds ...... 123

Figure 3-1. Geographic maps denoting the location of the Ruth Mason Dinosaur Quarry (RMDQ) ...... 195

Figure 3-2. Examples of retrodeformation of RMDQ transverse cross-sections ...... 197

Figure 3-3. Combined size-frequency distributions comprised of humeri, femora, and tibiae from RMDQ ...... 199

Figure 3-4. Total length size-frequency distributions of individual long bone elements from RMDQ...... 201

Figure 3-5. Minimum diaphyseal circumference size-frequency distributions of individual long bone elements from RMDQ ...... 203

Figure 3-6. Combined total length size-frequency distribution of metacarpals and metatarsals from RMDQ ...... 205

Figure 3-7. Osteohistology of humeri from RMDQ ...... 207

Figure 3-8. Osteohistology of femora from RMDQ ...... 209

Figure 3-9. Osteohistology of tibiae from RMDQ ...... 211

Figure 3-10. Edmontosaurus annectens growth curves ...... 213

Figure 3-11. Summary of section stacking of RMDQ tibiae ...... 215

Figure 3-12. Density comparison of long bone and tracksite size distributions of hadrosaurid bonebeds ...... 217

Figure 3-13. Latitudinal comparison of Edmontosaurus bonebeds ...... 219

Figure 3-14. Osteohistology of the right humerus of Anatotitan (CCM V 1938.8) ...... 221

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List of Supplementary Tables

Supplementary Table S1-1. Edmontosaurus measurements used in bivariate analyses ...... 59

Supplementary Table S1-2. Ordinary Least Squares (OLS) results from the bivariate morphometric analyses of appendicular element variables against total femur length (x) ...... 62

Supplementary Table S1-3. Ordinary Least Squares (OLS) results from the bivariate morphometric analyses of minimum diaphyseal circumference, combined limb length, and intra-bone variables ...... 65

Supplementary Table S2-1. Summary of total length and minimum diaphyseal circumference data of associated skeletons from the DPF used in SMA analyses ...... 125

Supplementary Table S2-2. Results from SMA regression analyses using associated skeletons from the DPF ...... 128

Supplementary Table S2-3. Results from OLS regression analyses using complete isolated elements ...... 130

Supplementary Table S2-4. Parameter values for each age retrocalculation growth model .....132

Supplementary Table S2-5. Parameter values for each age retrocalculation growth model after the first (earliest/smallest) recorded growth mark was artificially removed from each specimen’s dataset ...... 135

Supplementary Table S2-6. Parameter values for each body mass growth model along with AICc scores ...... 138

Supplementary Table S3-1. Results from OLS regression analyses using complete elements from RMDQ ...... 223

Supplementary Table S3-2. Parameter values for each age retrocalculation growth model along with AICc scores ...... 225

Supplementary Table S3-3. Parameter values for each body mass growth model along with AICc scores ...... 227

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List of Supplementary Figures

Supplementary Figure S2-1. Bivariate allometric results of DPF hadrosaurids ...... 141

Supplementary Figure S2-2. Size-frequency distributions of hadrosaurid radii, ulnae, and fibulae from the Dinosaur Park Formation (DPF) of Alberta, Canada ...... 143

Supplementary Figure S2-3. Size-frequency distributions of humeral and femoral minimum diaphyseal circumferences integrated with osteohistology ...... 145

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List of Appendices

Appendix 2-1. Total length and minimum diaphyseal circumference data of all specimens using in Dinosaur Park Formation (DPF) analyses...... 251

Appendix 3-1. Total length and minimum diaphyseal circumference data of all specimens used in Ruth Mason Dinosaur Quarry (RMDQ) analyses...... 266

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List of Institutional Abbreviations

AMNH American Museum of Natural History, New York, New York, U.S.A.

BHI Black Hills Institute of Geological Research, Hill City, South Dakota, USA

CCM Carter County Museum, Ekalaka, Montana, U.S.A.

CMN Canadian Museum of Nature, Ottawa, Ontario, Canada

CMNH Cleveland Museum of Natural History, Cleveland, Ohio, U.S.A.

DMNH Denver Museum of Natural History, Denver, Colorado, U.S.A.

FPDM Fukui Prefectural Dinosaur Museum, Katsuyama, Japan

LACM Los Angeles Country Natural History Museum, Pasadena, California, U.S.A.;

MCSNM Museum Civico di Storia Naturale di Milano, Milan, Italy

MOR Museum of the Rockies, Bozeman, Montana, U.S.A.

MPC Institute of Paleontology and Geology, Mongolian Academy of Sciences, Ulaan

Baatar, Mongolia

NCSM North Carolina Museum of Natural Sciences, Raleigh, North Carolina, U.S.A.

NHMUK PV Natural History Museum, London, England

PIN Paleontological Institute, Russian Academy of Sciences, Moscow, Russia

ROM Royal Ontario Museum, Toronto, Ontario, Canada

SDSM South Dakota School of Mines and Technology, Rapid City, South Dakota,

U.S.A.

SM Senckenberg Naturmuseum, Frankfurt, Germany

TCM The Children’s Museum of Indianapolis, Indianapolis, Indiana, USA

TMP Royal Tyrrell Museum of Paleontology, Drumheller, Alberta, Canada

UALVP University of Alberta Laboratory of Vertebrate Paleontology, Edmonton,

Alberta, Canada

UCM University of Colorado Museum, Boulder, Colorado, U.S.A.

UCMP University of California Museum of Paleontology, Berkeley, California, U.S.A.

USNM Smithsonian National Museum of Natural History, Washington, D.C. , U.S.A.

UWBM University of Washington Burke Museum, Seattle, Washington, U.S.A.

UWGM University of Wisconsin Geological Museum, Madison, Wisconsin, USA

YPM-PU Yale Peabody Museum of Natural History, New Haven, Connecticut, U.S.A.

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Background and Context

Data on the life history of an organism provides an important window into its biology, ecology, and evolution (e.g. Deevey 1947; Voorhies 1969; Erickson 2016). The study of ontogenetic morphological change, growth strategies, and population dynamics can be easily obtained in extant vertebrates, but it has been challenging to apply to extinct organisms due to limitations of fossil sampling and the inability for direct observation. The recognition of cyclical tree-like growth marks, including lines of arrested growth (LAGs), denoting annual cessation of bone growth in a wide range of extant and extinct animal bones have proven invaluable for estimating ontogenetic age of individuals in all major vertebrate groups (e.g. Peabody 1961; Halliday and

Verrell 1988; de Buffrenil and Castanet 2000; Chinsamy-Turan 2005; Bourdon et al. 2009;

Woodward et al. 2011; Köhler et al. 2012). This has revolutionized paleontological growth studies and permitted quantitative assessment of numerous aspects of life history in extinct organisms (Erickson 2005; Erickson 2014; Erickson 2016). To date, osteohistological life history studies have been concentrated on dinosaurs. Based on these studies, we now recognize that most dinosaurs grew rapidly, both disruptively and determinately (Chinsamy-Turan 2005; Woodward et al. 2013), attained large body sizes through accelerated growth (Erickson et al. 2001), and were dwarfed through abbreviated development (Sander et al. 2006; Weishampel and Jianu

2011) while rarely, if ever, attaining a half century in age (Sander 2000; Horner and Padian

2004). They likely matured sexually similar to crocodiles (Erickson et al. 2007), exhibited survivorship patterns similar to populations of large bodied mammals (Erickson and Tumanova

2000; Erickson et al. 2006), and basal ancestors of birds, extant dinosaurs, sustained dinosaurian physiologies (Chinsamy-Turan 2005; Erickson et al. 2009), which were elevated with respect to other reptiles (Grady et al. 2014; D’Emic 2015).

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Hadrosaurs, or duck-billed ornithischian dinosaurs, rank among the most diverse dinosaur groups and were the dominant large-bodied terrestrial herbivores in most Laurasian ecosystems in the last 15 million years of the Mesozoic (Campanian-Maastrichtian) (Horner et al. 2004). Their remains are often prolific, ranging from isolated elements to complete articulated skeletons that have been found across Europe, Asia, North and South America, and Antarctica (Case et al.

2000; Lund and Gates 2006; Prieto-Márquez 2010b). Hadrosauridae, a clade of herbivores known for their distinctive nasal crests and highly derived dental batteries, is comprised of two major subclades; the Hadrosaurinae and Lambeosaurinae are primarily distinguished on the basis of their nasal anatomy (Lull and Wright 1942; Horner 1990; Horner et al. 2004). Many taxa are known from numerous skeletons and bonebeds, representing a wide range of ontogenetic stages

(including eggs and embryos for some taxa), providing some of the most extensive fossil datasets of any dinosaur group (Horner et al. 2004) and are therefore, an ideal clade for which to conduct life history studies.

Osteohistological surveys of the hadrosaurid Maiasaura peeblesorum have provided significant insights into hadrosaurid life history and demonstrated that skeletal maturity and senescence occurred after 8 years in Maiasaura (Woodward et al. 2015) and that age and size classes were correlated (Horner et al. 2000). Furthermore, a biomechanical assessment hypothesized that

Maiasaura individuals underwent an ontogenetic gait change from bipedal juveniles to quadrupedal adults (Dilkes 2001). However, these conclusions have been extrapolated to all hadrosaurids despite an abundance of material from other taxa (Horner et al. 2004; Erickson

2016). To test these inferences, I use Edmontosaurus, which has a wide ontogenetic sample of associated skeletons and bonebed occurrences (Wosik et al. 2017b; Chapter 3 and references therein), and compare with hadrosaurids from the Dinosaur Park Formation of Alberta, an incredibly fossiliferous paleo-ecosystem, to better understand the data in a larger context and xxiii assess whether larger assemblages provide further insight towards population structure and the paleoecological of these animals.

The objectives of this thesis were to integrate new data and methods to investigate ontogenetic growth and test life history strategies in hadrosaurid populations from the Late Cretaceous of

In particular, I was interested in answering the following questions:

1) Did Edmontosaurus undergo an ontogenetic gait shift from predominantly bipedal

juveniles to quadrupedal adults, and if so, how did this affect the individual skeletal

growth of the animal?

2) Are body size and age strongly correlated in hadrosaurid dinosaurs?

3) How did the growth and the life history strategies of Edmontosaurus and hadrosaurids

from the Dinosaur Park Formation compare to other closely related taxa?

From these questions, I hypothesized:

1) A shift from bipedality to quadrupedality occurred in Edmontosaurus early in ontogeny

and at a small body size similar to the timing as suggested for Maiasaura.

2) Size and age were more tightly correlated early in ontogeny.

3) The growth rate of Edmontosaurus rapidly increased during early development and

subsided after a threshold body size was reached. The hadrosaurids from the Dinosaur

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Park Formation had a faster growth rate than penecontemporaneous taxa from the Two

Medicine Formation.

Chapter one is published in the Journal of Vertebrate Paleontology. I am the primary author on this publication and all coauthors are listed at the start of the chapter. I plan to submit chapters two and three as lead-authored papers in the near future with the indicated coauthors.

xxv 1

Chapter 1

A nestling-sized skeleton of Edmontosaurus (Ornithischia,

Hadrosauridae) from the Hell Creek Formation of northeastern

Montana, U.S.A., with an analysis of ontogenetic limb allometry

Mateusz Wosik1, Mark B. Goodwin2, and David C. Evans1,3

1Department of Ecology and Evolutionary Biology, University of Toronto, 100 Queen’s Park,

Toronto, Ontario, M5S 2C6, Canada, [email protected]

2Museum of Paleontology, University of California, 1101 Valley Life Sciences Building,

Berkeley, California, 94720, U.S.A., [email protected]

3Department of Natural History, Royal Ontario Museum, 100 Queen’s Park, Toronto, Ontario,

M5S 2C6, Canada, [email protected]

Published as (cited herein as Wosik et al. 2017b):

Wosik, M., M. B. Goodwin, and D. C. Evans. 2017. A nestling-sized skeleton of Edmontosaurus

(Ornithischia, Hadrosauridae) from the Hell Creek Formation of northeastern Montana,

U.S.A., with an analysis of ontogenetic limb allometry. Journal of Vertebrate

Paleontology 37(6):e1398168. https://doi.org/10.1080/02724634.2017.1398168

1.1 Abstract

The Hell Creek Formation preserves one of the most intensely studied late Cretaceous terrestrial fossil units. Over 22 dinosaur genera are currently recognized from this unit, but the record of juvenile individuals is surprisingly limited. Here we document a nestling hadrosaur that represents the first occurrence of an articulated nestling dinosaur skeleton from the latest

Cretaceous (late Maastrichtian) of North America. The specimen (UCMP 128181) preserves a partial scapula, nearly complete rib cage, vertebral series from the shoulder to mid-tail, a large portion of the pelvic girdle, and both hindlimbs through a combination of bone and/or natural impressions in the concretion. It is assignable to the genus Edmontosaurus based on the shape of the prepubic process, or blade, of the pubis.

UCMP 128181 represents the earliest ontogenetic growth stage of Edmontosaurus cf. annectens and possesses a femur length of 148 mm. It greatly contributes as a new end member to a sample of associated Edmontosaurus skeletons that is well suited for allometrically testing the hypothesized ontogenetic gait shift in hadrosaurs from bipedal juveniles to quadrupedal adults using individual limb proportions. Although UCMP 128181 does not preserve forelimbs, regressions based on associated Edmontosaurus skeletons (N = 25) reveal overall isometry of the forelimb relative to the hindlimb, and within each limb. These data indicate Edmontosaurus nestlings were anatomically capable of fully quadrupedal locomotion, and provide no compelling evidence to support an ontogenetic gait shift in hadrosaurids.

1.2 Introduction

The Hell Creek Formation has been intensely collected for over a century making it one of the best-sampled late Cretaceous terrestrial units (e.g., Hartman, 2002; Pearson , 2 2002; Russell and

Manabe, 2002; Horner et al. 2011; Lyson and Longrich, 2011, Clemens and Hartman, 2014;

Scannella and Fowler, 2014; Fastovsky and Bercovici, 2016). At the turn of the 20th century, the early expeditions of Barnum Brown and others led to the first major dinosaur discoveries of the iconic Tyrannosaurus, Triceratops, and Edmontosaurus and established the Hell Creek strata as a rich source of vertebrate fossils from a critical period in Earth’s history (Clemens and Hartman,

2014). To date, there are over 22 dinosaur genera representing both large and small-bodied forms recognized from the formation (Russell and Manabe, 2002) with preservation ranging from articulated individuals (e.g. Brown, 1907; Garstka and Burnham, 1997) to multiple bonebed occurrences (e.g. Christians, 1992; Colson et al., 2004; Mathews et al., 2009; Keenan and

Scannella, 2014).

A recent dinosaur census of the Hell Creek Formation in northeastern Montana found the horned dinosaur Triceratops was the most common dinosaur recovered as a skeleton from this well sampled unit, and Tyrannosaurus was equally as common as the duck-billed Edmontosaurus

(Horner et al., 2011). Juveniles of all taxa are surprisingly rare, with only Triceratops (Goodwin et al., 2006; Horner et al., 2011) and Tyrannosaurus (Hutchinson et al., 2014) known from multiple specimens spanning a relatively wide ontogenetic range. Small juvenile and perinatal individuals have only been reported on the basis of rare and highly fragmentary remains, albeit from the contiguous Lance and Frenchman formations (Carpenter, 1982; Tokaryk, 1997), and dinosaur egg and egg shell have only recently been described (Jackson and Varricchio, 2016).

The hadrosaurine hadrosaurid (sensu Xing et al., 2014, 2017) Edmontosaurus annectens is one of the most common dinosaur taxa from the Hell Creek Formation, yet it is known primarily from specimens representing later ontogenetic stages (Campione and Evans, 2011; Xing et al., 2014,

2017). The smallest and presumably youngest described ontogimorph (Goodwin and Evans,

2016) of Edmontosaurus annectens is LACM 23504 with a femur length approximately 40% of average adult size (Prieto-Márquez, 2014). Here, we present the smallest (estimated ~70 cm total body length) articulated skeleton of Edmontosaurus cf. annectens, UCMP 128181, discovered in

1980 by Harley Garbani in Garfield County, Montana. This specimen was briefly mentioned in

Russell and Manabe (2002:173) but was neither illustrated nor described. This is the first record of an articulated nestling dinosaur skeleton from the Hell Creek Formation, and it greatly expands the known ontogenetic continuum for Edmontosaurus. The wide ontogenetic sample of this taxon permits the first allometric study of limb proportions in a hadrosaurid using associated skeletons and contributes new insights to the ongoing debate whether hadrosaurids underwent a gait shift from bipedality in juveniles to quadrupedality in adults (Dilkes, 2001).

1.3 Geological Setting

UCMP locality V80092 is located on land managed by the Bureau of Land Management in

Garfield County, Montana (Fig. 1-1). In situ and weathered bone originates from a series of stacked channels with multiple lag deposits in a complex of cut and filled cross-stratified channel sandstones in the upper Hell Creek Formation, about 10–15 meters below the Z coal complex, which marks the top of the Hell Creek Formation in this general area (Sprain et al., 2015). Here, three different coals are separated by less than one meter. The Hell Creek Formation exposures

5 are extensive and characterized by white-weathering channel sandstones in the flats where abundant and often water-worn dinosaur bone is found, in addition to partly articulated turtles, crocodilian bones, and microvertebrate fossils. The sandstone is generally friable but can be locally cemented into < 1 meter elliptical-to-round, iron-cemented concretions. One of these concretions produced the articulated, nestling-sized skeleton, UCMP 128181, described here.

Detailed locality information is on file at the UCMP. All permissions were obtained for land access, collecting, and curation of these fossils into the UCMP in 1980 and on additional visits by UCMP field crews in 1983 and 2016.

1.4 Materials and Methods

UCMP 128181 is preserved in an ovoid sandstone concretion that measures ~60 cm on its long axis. The sandstone concretion was broken prior to collection into several larger pieces, some of which have been consolidated and glued back together. The main block (Fig. 1-2) hosts the largest portion of the specimen and consists of the majority of the right side of the skeleton. The counterpart (Fig. 1-3) is composed of several smaller pieces intentionally left separated and primarily comprises the left side of the skeleton. The extreme fragmentary nature of additional miscellaneous pieces associated with UCMP 128181 makes bone identification difficult, and they have been omitted from this description. The specimen was photographed using a Nikon

D5300 DSLR camera with a Tamron AF 18–200 mm f/3.5–6.3 XR Di II LD Aspherical (IF) macro zoom lens (Model A14NII) and interpretive outline drawings were executed in Adobe

Illustrator by M. W. In addition, a photogrammetric 3D was constructed using Agisoft

PhotoScan version 1.2.6 and uploaded to MorphoSource as supplemental data (MorphoSource,

Media Group M15342).

1.4.1 Measurements

For the allometric limb proportion study, appendicular measurements were gathered by the authors first-hand, from the published literature, and through the help of colleagues from a total of 25 associated skeletons of Edmontosaurus, representing both E. annectens and E. regalis

(Supplementary Table S1-1). Linear measurements under 30 cm were taken with digital calipers, while those over 30 cm and all circumferences were taken using a fabric tape measure. Where data from left and right elements from the same specimen are taken, the measurements are averaged prior to the analyses. Data from specimens with a high degree of postmortem deformation (e.g. crushing, flattening) were excluded from the analyses. Linear measurements of

UCMP 128181 are included in Tables 1-1 and 1-2. The femur circumference of UCMP 128181 is incomplete and required estimation prior to the allometric analyses. The preserved half circumference of the right femur was measured using ImageJ 1.48v (Rasband, 1997–2014) from a digital cross-section and doubled to produce an estimated minimum femur circumference of 60 mm for UCMP 128181. Results from the allometric analyses are reported in Tables 1-3 and 1-4.

A summary of estimated values for missing elements of UCMP 128181 are listed in Table 1-5.

Measurements of specimens used in the size comparison of perinatal and nestling hadrosaurs were gathered from the literature and are recorded in Table 1-6.

1.4.2 Regression Analyses

The complete dataset of Edmontosaurus linear measurements was analyzed for the allometric trajectories of 25 different appendicular comparisons to describe the best functional relationships

7 among variables of the forelimb and hindlimb and within each limb apparatus (Tables 1-3 and 1-

4). These 25 comparisons were further subdivided to the species level and repeated by removing the nestling UCMP 128181 individual. The purpose of this subsampling was: (1) to determine whether the relationships significantly changed when the overall dataset was subsampled; and (2) whether the sole nestling specimen was potentially an outlier. Linear data were log-transformed prior to analysis using natural log (ln). Comparisons 1–15 were plotted against the reference datum, femur length, for the entire sample size. Femur length is an appropriate standard variable for this study because it is frequently used as a size proxy in allometric studies of the appendicular skeleton in terrestrial vertebrates, and unlike the forelimb, the hindlimb is typically used in locomotion in terrestrial vertebrates (e.g. Campione and Evans, 2012). Standardized

(Reduced) Major Axis (SMA or RMA; Tables 1-3 and 1-4) regressions were used to describe allometric relationships because they assume that both variables contain error from inaccurate measurements (Warton et al., 2006). Ordinary Least Squares (OLS) (Supplementary Tables S1-2 and S1-3) regressions were used to predict the size of missing or incomplete elements in UCMP

128181 (Warton et al., 2006), with femur length set as the standard variable, but these estimates were not included in any of the SMA analyses. This was particularly useful for determining an approximate size for the missing forelimb of the nestling individual (UCMP 128181). However, we do not use these estimates as primary data, but only to compare with forelimb-hindlimb ratios of articulated embryos and nestlings of other taxa as an external test of the feasibility of our allometric relationships. Table 1-5 contains summarized results in the form of percent (%) error taken as a ratio of the raw value to the OLS estimation. Slopes, intercepts, 95% confidence intervals, and correlation coefficients were determined for each comparison. Each comparison was evaluated using two-tailed p-values using a significance level of 0.05 for correlation between variables. Furthermore, the results of each regression were assigned as positively

8 allometric (95% confidence interval of slope is greater than 1), negatively allometric (95% confidence interval of slope is less than 1), or isometric (95% confidence interval of slope includes 1). The regressions and statistical analyses were performed in R (R-Development-Core-

Team, 2016) with the package ‘lmodel2’ (Legendre, 2008).

1.4.3 Body Mass Estimation

The photogrammetric 3D model was digitally sectioned using Agisoft PhotoScan version 1.2.6 at the minimum diaphyseal circumference of the right femur between the fourth trochanter and distal end. In order to estimate the body mass of UCMP 128181, Developmental Mass

Extrapolation (DME) was used (Erickson and Tumanova, 2000). Body mass estimates were made on the basis of femur length and circumference measurements. The mounted CCM skeleton was used as the morphologically adult-sized individual in DME calculations.

1.5 Systematic Paleontology

ORNITHISCHIA Seeley, 1887

ORNITHOPODA Marsh, 1881

IGUANODONTIA Dollo, 1888

HADROSAURIDAE Cope, 1869

HADROSAURINAE Cope, 1869

EDMONTOSAURUS Lambe, 1917

EDMONTOSAURUS cf. ANNECTENS Marsh, 1892

1.6 Description and Ontogenetic Comparison

Due to the nature of preservation, UCMP 128181 can only be described at a gross anatomical level. Most bones are preserved as a natural mold, in which original bone is heavily fractured or is completely eroded away. Periosteal surfaces, delicate processes, and muscles scars are generally not preserved, particularly in the elements of the pelvic region. Fortunately, the primary dimensions (e.g. total lengths and widths) are easily measured and provided in Table 1-1 for vertebrae and Table 1-2 for the appendicular skeleton. For color figures, the reader is referred to the web version of this article. A 3D photogrammetric model of the main block is available online (MorphoSource, Media Group M15342).

1.6.1 Axial Skeleton

1.6.1.1 Dorsal Ribs

Fourteen dorsal ribs are preserved primarily as impressions in the main block with varying degrees of preservation (Fig. 1-4). Starting with the anterior-most rib impression near the minimum constriction of the scapula, the length of the ribs increases to its longest just distal of this constriction and is succeeded by a dramatic reduction in length and robustness towards the final preserved rib impression. These progressively distinct features imply the four missing dorsal ribs are those near the sacrum. It is not possible to determine the shape of the articulating ends.

1.6.1.2 Dorsal Vertebrae

Seven dorsal centra with incomplete posteriorly deflected neural spines are preserved primarily as impressions in the main block (Fig. 1-4). Edmontosaurus is reported to have 18 to 20 dorsal vertebrae (Gilmore, 1924; Lull and Wright, 1942). Assuming the anterior-most preserved dorsal rib impression represents the first dorsal rib, the first preserved dorsal centrum would be the eighth (d8). It is not possible to determine the shape of the faces of the centra or orientation of zygapophyses due to the specimen being preserved in medial orientation. However, the more anterior dorsal centra are longer and shallower and their lateral sides are less concave anteroposteriorly than those centra closer to the sacrum, as in other hadrosaurs (Horner et al.,

2004).

1.6.1.3 Sacral Vertebrae

The anterior end of the sacrum is either covered by sediment or eroded away but the four posterior-most vertebrae of the sacrum are preserved in articulation with the first free caudal and identified as sacrals on the basis of fusion (Fig. 1-5). Edmontosaurus has nine fused sacrals (Lull and Wright, 1942) and following the conventional numbering of vertebrae, UCMP 128181 preserves sacrals six through nine. Fragmentary neural spines are canted posterodorsally and are preserved for these vertebrae (s8, s9), but the sacral ribs are not.

1.6.1.4 Caudal Vertebrae

Eight caudal centra with four accompanying neural spines are preserved primarily as impressions in the main block (Fig. 1-5A) whereas the counterpart preserves only five centra as impressions

(Fig. 1-5B). We interpret the first free vertebra (c1) posterior to the fused sacral bar as the first

11 caudal. Similar to the dorsal vertebrae, it is not possible to determine the shape of the articulating ends. The more anterior centra are longer and shallower with stronger concave lateral sides than the more posterior centra, which expand slightly dorsoventrally and decrease to less than one- third of the size of the first caudal (Table 1-1). The base of the tail is straight and projects horizontally from the sacrum, as in other articulated skeletons of Edmontosaurus (Gilmore

1924). The four posterodorsally deflected neural spines, three of which are almost complete, exhibit an anteroposterior reduction in height and width distally along the tail. Several anteroposteriorly orientated ossified tendons overlap the neural spines in the region of the tail base.

1.6.2 Pectoral Girdle

1.6.2.1 Scapula

The right scapula is preserved posteriorly from the proximal neck constriction (Fig. 1-4). The scapula is represented by an impression in the main block that is lateral to the preserved ribcage, and the dorsal ribs have weathered away along with the scapula in this region. The scapula is a long (> 88 mm) and arched bone with a weakly curved dorsal margin and a gradually dorsoventrally expanding distal blade. The disparity between the minimum dorsoventral height of the proximal constriction relative to the maximum dorsoventral height of the blade (~53%) is comparable to the juvenile LACM 23504, but is slightly greater than typical of adult specimens

(>60%, Prieto-Márquez, 2014). The scapular blade terminates posteriorly on dorsal rib seven.

1.6.3 Pelvic Girdle

1.6.3.1 Ilium

The right and left ilia are preserved as impressions in the main block (Fig. 1-6A) and counterpart

(Fig. 1-6C), respectively. The dorsal margin of the thin preacetabular process, visible on the main block, gently deflects ventrally towards its anterior end. The preacetabular process has a rounded anterior termination present on the counterpart but dives behind the matrix. The impression of the tall posteriorly projecting postacetabular process has a possible weak dorsal expansion just anterior to its rounded posterior end. As preserved, the ilium is 105 mm in total length but is missing portions of both ends. The region above the acetabulum is the tallest dorsoventrally and the most robust portion of the ilium. There is a strong inflection in the dorsal margin above the acetabulum, as is characteristic of Hadrosauridae inclusive of Bactrosaurus and Gilmoreosaurus (Brett-Surman and Wagner, 2007). The counterpart contains an incomplete impression of the pubic peduncle but it is difficult to distinguish between its ventral termination and the origination of the iliac peduncle of the pubis. The supracetabular crest and ischial peduncle are not well preserved.

1.6.3.2 Pubis

Parts of the right and left pubes are well preserved as impressions in the main block and counterpart (Fig. 1-6), respectively. The right side has a virtually complete prepubic process

(blade), with clear, complete margins except in the region adjacent to the acetabulum. Because of this, the iliac peduncle is difficult to discern from the origination of the pubic peduncle of the ilium, and the ischial peduncle is obscured by the femur. The height of the neck at the minimum constriction measures 11.4 mm, which is 45% the maximum dorsoventral height of the expanded

13 blade. In lateral view, the right pubis has a relatively long proximal constriction and a paddle- like, asymmetrical and subellipsoidal anterior end that expands more ventrally than dorsally, as is typically observed in Edmontosaurus (e.g. CMN 2289, Campione, 2014; LACM 23504,

Prieto-Márquez, 2014) and remains morphologically unchanged ontogenetically (Brett-Surman and Wagner, 2007; Prieto-Márquez, 2014). The long postpubic process is preserved as bone and only visible on the counterpart. It is in natural position below the anterior end of the ischium and nearly parallels its ventral margin. The distal end of the postpubic process is broken but a 129 mm portion of the left pubis is preserved.

1.6.3.3 Ischium

The triangular body of the left ischium is preserved as an impression on the counterpart (Fig. 1-

6C). Although the dorsal and anterior terminations of the iliac and pubic peduncles are eroded away, the acetabular margin provides an estimate for the orientation of each peduncle. This indicates the ischium is preserved in natural articulation with the ilium and pubis. The iliac and pubic peduncles are comparatively similar to each other. Along the ventral margin of the ischial body, a broad obturator notch, preserved on the counterpart, is at least partially enclosed posteriorly. In lateral view, the obturator notch is lenticular in shape, with the posterior end of the aperture more acute than the apparently poorly ossified anterior region. It is open, as expected in early ontogeny, and resembles the first stage of progressive ossification (Brett-

Surman and Wagner, 2007). The caudal shafts of both ischia appear to be nearly complete distally, with rounded distal termini preserved as impressions with fragments of bone on the main block (Fig. 1-2). The minimum expansion of the distal end of the ischium is consistent with

Edmontosaurus and other hadrosaurines, and distinct from the expanded boot of lambeosaurines

(Brett-Surman and Wagner, 2007). When the main block and counterpart are aligned, the left ischium is 137 mm long.

1.6.4 Hindlimb

1.6.4.1 Femur

The left (Fig. 1-7A) and right (Fig. 1-7B) femora are nearly complete and in articulation relative to the acetabulum. The right femur is composed of eroded bone in the main block with a large dorsoventral crack permeating through it, whereas the left femur is represented by a detailed impression of the lateral side in the counterpart. The shafts of the femora are straight in medial view, but due to their orientation, it is difficult to determine whether there are any differences between the proportions of the proximal versus distal shaft regions. The fourth trochanter occurs at approximately the midpoint of the diaphysis, as in adult hadrosaurids (Brett-Surman and

Wagner, 2007), as well as juvenile and adult Edmontosaurus annectens (Prieto-Márquez, 2014) and Maiasaura peeblesorum (Guenther, 2014). The dorsal and ventral margins of the fourth trochanter preserve a symmetrical triangular outline in medial view, as seen in juveniles but not adults of Edmontosaurus annectens (Prieto-Márquez, 2014). The muscle attachment sites for the hindlimb extensors and flexors, as well as the m. gastrocnemius and m. tibialis anterior, observed on the left femur occur in positions reported for other hadrosaurs (Dilkes, 2000), including

Edmontosaurus (Maidment et al., 2014). The average total length of the femora is 148 mm, which is slightly longer than the ischium and 109% the length of the right tibia. The femur length compares to 26% of the LACM 23504 juvenile and 15% of the adult YPM-PU 2182.

1.6.4.2 Tibia

The right tibia is mostly preserved as an impression on the main block (Fig. 1-7C), whereas the left tibia only preserves a portion of the shaft as an impression in the counterpart. The tibia has a total length of 136 mm and is slightly shorter than the femur. The long axis of the proximal end, which includes the proximal condyles and the top of the cnemial crest, is orientated along an anterior-posterior plane, whereas the distal end is transversely oriented. The posterior end, which can be seen as an embossed impression, is preserved in the same plane as the surface of the main block and the cnemial crest extends down the proximal third of the tibia. The diaphysis of the tibia is straight and circular to triangular in cross-section. The distal end dives into the block, and therefore, comparison of the robustness between the proximal to distal ends is not possible.

1.6.4.3 Fibula

The fibulae are incompletely preserved as impressions in the main block (Fig. 1-7C) and counterpart. The right fibula is articulated with the right tibia. The fibula is long and slender with an anteroposterior expanded distal head, visible on the counterpart. The proximal head is the larger of the two ends in hadrosaurs, but is not preserved in the main block because it articulates under the proximal half of the tibia. As a result, the total length of 113 mm for the right fibula was measured from the distal end of the fibula to the proximal end of the articulating tibia. The shaft has is cylindrical in cross-section. Prieto-Márquez (2014) noted the shaft becomes anteroposterior narrower towards the distal end through ontogeny. This may indicate the cylindrical shape is characteristic of early ontogenetic stages.

1.6.4.4 Astragalus

The right astragalus is likely represented as an impression in the main block (Fig. 1-7C) in articulation with the right tibia, but is insufficiently preserved to describe in any detail.

1.6.4.5 Pes

Only the right metatarsus is preserved as an impression in the counterpart of the anterior side in articulation (Fig. 1-8). Metatarsal II preserves part of its proximal end but is incomplete distally.

Metatarsal III is the largest in the series, and preserves a complete total length of 56.6 mm. It has a slightly expanded proximal end relative to its diaphysis, which maintains a consistent diameter along much of its length. The region of the distal end in articulation with Metatarsal II is not preserved but still provides enough evidence of a gradual mediolateral expansion directed distally. Metatarsal IV is the shortest in length (as preserved) and narrowest in maximum width among the three preserved tarsal elements. The proximal end originates just distal to the proximal end of Metatarsal III and is distally incomplete.

1.6.5 Taxonomic Identification

Significant morphological changes occur through hadrosaurid ontogeny and occasionally hinder precise taxonomic identification of juvenile ontogimorphs (e.g. Evans et al., 2005; Guenther,

2009; Prieto-Márquez, 2011). UCMP 128181 is recognized as a hadrosaurine hadrosaurid (sensu

Horner et al., 2004; Xing et al., 2014) based on a combination of ontogeny-independent characters (e.g. Evans et al., 2005; Brett-Surman and Wagner, 2007; Prieto-Márquez, 2011), or characters that do not significantly change with ontogeny in hadrosauroids. The minimum expansion of the distal end of the ischium is consistent with Edmontosaurus and other

17 hadrosaurines and is distinct from the expanded boot of lambeosaurines (Horner and Currie,

1994; Brett-Surman and Wagner, 2007; Prieto-Márquez, 2010a: Character 271[0, slightly expanded into a blunt end]). The prepubic process has a relatively long, shallow proximal constriction that terminates in an anterior paddle-like blade and is subellipsoidal and asymmetrical in lateral view (Prieto-Márquez, 2010a: Characters 253 [3, oval expansion, well pronounced concave profiles along neck]). The shape of the anterior end of the prepubic process varies in Hadrosaurinae and has been used to characterize hadrosaurid genera (Brett-Surman and

Wagner, 2007; Prieto-Márquez, 2010a). The prepubic process in UCMP 128181 expands more ventrally than dorsally, a morphology that characterizes the genus Edmontosaurus (Prieto-

Márquez, 2010a: Character 252 [1, ventral region is more expanded and directed ventrally];

Prieto-Márquez, 2014). Although none of the autopomorphies of E. annectens are present in

UCMP 128181 due to the lack of cranial material, we tentatively refer the specimen to this taxon because it is the only Edmontosaurus species known from the Hell Creek Formation despite over a century of intense collecting (Campione and Evans, 2011; Horner et al., 2011; Prieto-Márquez,

2014).

1.7 Results

1.7.1 Bivariate Analyses

Results of the limb regression analyses are presented in Figure 1-9 and Tables 1-3 and 1-4.

Although 25 associated Edmontosaurus skeletons were measured, relatively few are completely preserved for all the sampled variables; the most inclusive of the 25 comparisons included 22 specimens (comp. 12: tibia length). At the genus level, 24 out of 25 comparisons are based on 10

18 or more specimens. At the E. annectens species level, 15 out of 25 comparisons are based on 10 or more specimens, whereas comparisons at the E. regalis species level have small sample sizes and the lack of juvenile specimens severely limit their potential significance. The size distribution of the specimens is strongly left skewed making our sample biased towards adults.

This constitutes an ‘adult biased’ sample as defined by Brown and Vavrek (2015) suggesting the results are vulnerable to Type II errors given the small number of data points for each comparison. In general, comparisons pertaining to more distal elements (e.g. radius, metacarpals) had lower sample sizes for both the forelimb and hindlimb, which may be directly related to taphonomic modes of preservation. Coefficients of determination (R2) associated with the regressions using the genus-level dataset are generally high (> 0.92), although those associated with the zeugopodial and autopodial elements of the forelimb where the sample size is smaller tend to be lower (> 0.81).

1.7.1.1 Forelimb

Fifteen comparisons (comp. 1–10, 20–24 in Tables 1-3 and 1-4; Fig. 1-9A, B, D) describe the growth of the forelimb and were regressed against femur length or the respective element length.

At the genus level, two comparisons include the nestling UCMP 128181 (comp. 2: scapular blade height; comp. 3: scapular neck height) and have significant isometric relationships. When the data are subsampled at the genus level by removing the nestling UCMP 128181, the SMA slopes for the forelimb range between 0.926–1.300 demonstrating a high degree of isometry in the forelimb as a whole. However, 95% confidence intervals (1.01–1.50) of the SMA slope have a weak positively allometric trend for the ulna (comp. 9), although this weak trend is not reflected in the OLS results. A similar pattern is recovered for the comparison between scapula length and blade height (comp. 20), but this may be affected by incomplete preservation and/or

19 reconstruction of the distal region of the scapular blade in some of the larger specimens. At the

E. annectens species level, the SMA slopes range between 0.922–1.386 and provide isometric relationships except for comparison related to scapula blade height (comp. 2, 20)—one of two comparisons that include UCMP 128181. For E. regalis, only three (comp. 3: scapula neck height; comp. 4: humerus length; comp. 9: ulna length) of the thirteen comparisons pass a significance test of p < 0.05 and have weakly significant isometric relationships.

1.7.1.2 Hindlimb

Seven comparisons (comp. 11–15, 19, 25 in Tables 1-3 and 1-4; Fig. 1-9C, D), five of which use femur length as the standard variable, describe the growth of the major components of the hindlimb apparatus. At the genus level, three comparisons include UCMP 128181 (comp. 12: tibia length; comp. 14: fibula length; comp. 15: metatarsal III length) and have generally isometric relationships for the zeugopodial elements, whereas metatarsal III has a weak negatively allometric relationship. The slopes are tightly constrained and range between 0.921–

1.185 (SMA). When the data are subsampled by removing UCMP 128181, the slopes of the three hindlimb length comparisons (comp. 12, 14, 15) range between 0.971–1.030 (SMA), and the

95% confidence intervals of the SMA slopes indicate isometric trends, including the femur-tibia circumference comparison (comp. 19). At the E. annectens species level, all five comparisons have isometric relationships for the complete genus-level dataset and when UCMP 128181 is removed. For E. regalis, all five comparisons do not pass a significance test of p < 0.05.

1.7.1.3 Forelimb vs. Hindlimb

Three comparisons (comp. 16–18 in Table 1-4; Fig. 1-9E) describe the overall relationship between the forelimb and hindlimb apparatuses. UCMP 128181 does not contribute to these

20 results because the forelimb is not preserved. At the genus level, the comparison of the minimum diaphyseal circumference between the humerus and femur (comp. 18) is significantly linear and cannot be distinguished from isometry (slope = 1.025). Notably, the slopes of the SMA regressions are nearly 1.0 (Fig. 1-9F), which implies isometry between the stylopodial elements.

The same relationships are reflected for the E. annectens sample, but E. regalis does not pass significance tests. When the combined forelimb length (humerus + radius + metacarpal III) is regressed against the combined hindlimb length (femur + tibia + metatarsal III), the data have isometric relationships for all subsampled comparisons at the genus and species levels. When this comparison (comp. 16) itself is subsampled by removing the autopodial elements (comp. 17) to increase the sample size, the relationships remain isometric (slope = 1.069), except for the E. regalis species level that results in a weak negatively allometric relationship.

1.7.2 Estimation of Forelimb Lengths and Body Mass in UCMP 128181

OLS regression of the genus-level dataset was used to predict missing data for UCMP 128181, with particular reference to the forelimb comparisons (Table 1-5). With respect to the total length of the forelimb (humerus [comp. 4] + radius [comp. 8] + metacarpal III [comp. 10]), a notable discrepancy of 9 mm occurs between the sum of individual limb element estimates (184.9 mm) and where they are considered in concert as a single variable (comp. 16; 193.9 mm). A similar discrepancy occurs for the humerus+radius variable (comp. 17) between the OLS predicted value

(149.4 mm) and the summative value (140.6 mm). Therefore, we predict the total length of the forelimb for UCMP 128181 is between 185 mm and 194 mm, with a 5% error range among different manipulations of the dataset.

Body mass of UCMP 128181 was estimated using the length (148 mm) and estimated circumference (60 mm) of the right femur. When using the adult-sized CCM E. annectens

21 skeleton as a comparative standard (body mass estimate = 6,922 kg ± 1,772 kg via Equation 1 of

Campione and Evans, 2012) for Developmental Mass Extrapolation, UCMP 128181 was estimated to have weighed 14.7 kg based on femur length and 12.7 kg based on femur circumference.

1.8 Discussion

The UCMP 128181 skeleton is the youngest known ontogimorph of Edmontosaurus (Campione and Evans, 2011) and one of the smallest non-embryonic hadrosaurid skeletons on record with a femur length of 148 mm and an estimated body mass of 14 kg. For comparison, previously reported hadrosaurid egg volumes (Horner, 1999) were converted using an average bird egg content density of 1.031 kg/m3 (Rahn et al., 1982). This provided approximate body mass estimates of 1–4 kg for freshly hatched hadrosaurids, whereas body mass estimates for the previously smallest Edmontosaurus juvenile LACM 23504 skeleton are approximately 791 kg

(femur length) and 627 kg (femur circumference). Horner et al. (2000) defined ontogenetic growth stages in Maiasaura based on osteohistological criteria, body size, and egg, nest, and adult associations, a system that has been extended to other hadrosaurids (Table 1-6). The categorization used for Maiasaura identified two stages of nestlings: ‘early nestling’ with a femur length of 70 mm and a ~450 mm body length and ‘late nestling’ with a femur length of

120 mm and a ~900 mm body length (Horner et al., 2000). Embryos attributed to the lambeosaurine Hypacrosaurus have a femur that reaches approximately 80 mm in total length, and nestlings of this taxon considerably exceeded the body size of Maiasaura late nestlings by almost double. This suggests lambeosaurines were larger at hatching than hadrosaurines and is

22 consistent with the known difference in egg sizes between these two taxa (Horner, 1999).

Additionally, Barsbold and Perle (1983) reported on the remains of baby hadrosaurs with femur lengths of 40–50 mm associated with nesting sites from the Tugrikin Shire locality of Mongolia, and recent finds of partially articulated Saurolophus specimens associated with eggshells from the Nemegt Formation of Mongolia were identified as embryos with a femur length of 43.5 mm

(Dewaele et al., 2015).

The femur length of UCMP 128181 is slightly longer than late nestlings of Maiasaura, but is significantly shorter than nestlings of Hypacrosaurus. Edmontosaurus adults attain a larger body size than Maiasaura. Therefore, we predict Edmontosaurus neonates were slightly larger than

Maiasaura neonates at hatching and attained a larger size during the nestling stage. For these reasons, we assign UCMP 128181 to the late nestling stage of Horner et al. (2000). Perinatal dinosaur material is very rare in the Hell Creek Formation and its equivalents (Russell and

Manabe, 2002; Horner et al., 2011), and to our knowledge, UCMP 128181 represents the only nestling dinosaur skeleton from the Hell Creek Formation and late Maastrichtian deposits of the

Western Interior. Carpenter (1982) described a partial left dentary (UCM 41666) and basioccipital (UCM 43218) and referred them to Saurornithoides (=Troodon) inequalis, along with a collection of small teeth, some of which belonged to presumably hatchling hadrosaurids

(UCM 45060; UCM 45061). Although this material originated from the contiguous Lance

Formation (UCM locality 77067 ‘Bushy Tailed Blowout’; also UCMP locality V5711), it represented the only documented evidence for hatchling dinosaur material from the late

Maastrichtian of the Western Interior Basin. Goodwin et al. (2006) described a relatively complete skull of the smallest and ontogenetically youngest Triceratops (UCMP 154452), and later inferred the previous lack of ontogenetically younger Triceratops from the Hell Creek

Formation to be, in part, a product of historical collection bias aimed in favor of larger and better

23 identifiable fossils preserved in sandstones in the field with little or no attention to mudstone deposits (Goodwin and Horner, 2014). However, limitations on the abundance of juvenile specimens may also be related to strong taphonomic biases against the preservation of small- bodied skeletons in fluvial systems (Brown et al., 2013a; Brown et al., 2013c).

1.8.1 Limb Allometry of Edmontosaurus and Gait Change in Hadrosaurs

Studies of relative cranial growth in hadrosaurid dinosaurs have documented extreme changes through ontogeny with the development of large cranial crests that greatly impacted our view of their taxonomy and biology (e.g. Dodson, 1975; Evans, 2010; Campione and Evans, 2011;

McGarrity et al., 2013; Freedman Fowler and Horner 2015). Compared to the skull, the ontogeny of the postcranial skeleton has not been studied intensely and only a few investigations of ontogenetic allometry have been conducted to date (Dilkes, 2001; Guenther, 2009; Kilbourne and Makovicky, 2010; Farke et al., 2013, Guenther, 2014). Dilkes (2001) used multivariate and bivariate morphometrics and the biomechanics of beam theory on a growth series of disassociated elements of Maiasaura peeblesorum and proposed a major gait shift from bipedal juveniles to quadrupedal adults in this taxon. This pattern was subsequently generalized among hadrosaurs (Horner et al., 2004). Herein, gait refers to the natural pattern of movement of the limbs during the animal’s predominant form of locomotion. This study of Edmontosaurus does not address cortical bones thickness or internal cross-sectional properties of the limb bones, which were critical in the formulation of the ontogenetic gait shift hypothesis of Dilkes (2001).

However, the ontogenetic analysis of limb proportions does provide the fundamental components of data for assessing this idea. Because few articulated skeletons are available for Maiasaura, metrics associated with ontogenetic changes in limb proportions within the skeleton (e.g. forelimb vs. hindlimb) used to hypothesize ontogenetic gait changes in other dinosaurs (e.g.,

Reisz et al., 2005; Zhao et al., 2013) could not be calculated for this taxon. The relative lengths and robustness of limbs have long been noted to differ between clades of hadrosaurids (Brett-

Surman and Wagner, 2007; Guenther, 2009), suggesting possible variability in hadrosaur locomotor dynamics. However, the ontogenetic gait shift hypothesis has not been investigated in any other hadrosaurid taxon despite an abundance of available material from numerous taxa. For

Edmontosaurus, the ontogenetic gait shift hypothesis can be corroborated if the forelimbs are relatively shorter than the hindlimbs in juveniles, and exhibit positive allometry through growth.

This prediction is based on the hypothesis of Dilkes (2001), in which juvenile hadrosaurs were primarily bipeds and shifted towards a quadrupedal stance with maturity and drastic limb scaling trends in other dinosaurian taxa with hypothesized gait shifts (Reisz et al., 2005; Zhao et al.,

2013).

Bivariate regression analyses based on articulated skeletons indicate a largely isometric relationship throughout the ontogeny of the postcranial limb skeleton in Edmontosaurus when analyzed at the genus and E. annectens species levels. The majority of comparisons at the E. regalis species level fail significance tests of correlation between variables, which can be attributed to a limited size range and small sample sizes and are not further discussed. At the genus level, the lengths of the forelimb elements, for which UCMP 128181 cannot be analyzed due to a lack of preservation, have near isometric relationships through ontogeny with the exception of ulna length (comp. 9), which exhibits very weak positive allometry (genus: R2 =

0.89, 95% CI m = 1.01–1.50) and is probably due to the elongation of the olecranon process

(Maidment and Barrett, 2014). However, at the E. annectens species level, growth of the ulna relative to the femur cannot be distinguished from isometry. The lengths and circumferences of the hindlimb elements (comp. 10–14, 25) reflect an even more tightly constrained, isometric relationship with the exception of the weak negatively allometric metatarsal III length (comp.

15). At the genus and E. annectens species levels, the analyses comparing the overall forelimb length to the hindlimb length (comp. 16–17) and the minimum diaphyseal circumference of the humerus and femur (comp. 18) exhibit isometry. Similar isometric trends in the limbs occur when the nestling UCMP 128181 specimen is excluded from the analyses, indicating UCMP

128181 is not strongly influencing the allometric results.

Dilkes (2001) observed weak negative allometry in intra-bone length and circumference regressions in Maiasaura peeblesorum for the humerus (RMA slope = 0.96), femur (RMA slope

= 0.95), and tibia (RMA slope = 0.97) suggesting a slight ontogenetic decrease in the robustness of these limbs through growth. Kilbourne and Makovicky (2010) also observed an ontogenetic decrease in robustness in equivalent intra-bone comparisons of Maiasaura and Hypacrosaurus.

The Edmontosaurus data presented here (comp. 11, 22, 25) differ from both of these studies in that the slopes of the intra-bone length to circumference in the humerus (1.19), femur (1.03), and tibia (1.19) trend slightly positive, but all are considered here to be isometric due to larger confidence intervals (Table 1-4). It is important to note that even though our sample sizes are occasionally limited, high R2 values (0.82 [humerus]; 0.89 [tibia]; 0.96 [femur]) and constrained confidence intervals of slopes indicate concordant trends of weak positive allometry in the robustness of all three of these major limb bones through ontogeny. Beyond hadrosaurids, obligate quadrupedal dinosaurs such as sauropods, stegosaurs, and ceratopsids (Kilbourne and

Makovicky, 2010) as well as the modern Alligator mississippiensis (Livingston et al., 2009) exhibit largely isometric trends in the robustness of their limbs through ontogeny with only a few notable exceptions (e.g. Agujaceratops, femur). Differences between Maiasaura,

Hypacrosaurus, and Edmontosaurus may be taxon specific and reflect different life history strategies in locomotor dynamics suggesting caution should be taken when extrapolating interpretations to larger clades.

The missing forelimb of UCMP 128181 is not optimal for testing the gait shift hypothesis early in ontogeny. However, its length can be estimated based on the remainder of the sample to compare with other associated individuals as an external test of the feasibility of the recovered limb relationships. We estimate the missing forelimb of UCMP 128181 was between 54–57% of the total hindlimb length (341 mm). This is comparable to the measured ratio in the only known

Edmontosaurus juvenile specimen LACM 23504 (59%), but is generally on the low end compared to the range of variation in presumably adult specimens of E. annectens in our dataset

(52% [USNM 2414], 58% [SDSM 4917], 62% [YPM-PU 2182], and 64% [AMNH 5730]).

Hypacrosaurus perinates (52% [MOR 548]; Horner and Currie, 1994) and nestlings (65% [ROM

53594]) fall within the range of variation for Edmontosaurus, whereas Saurolophus perinates exhibit a slightly larger forelimb-hindlimb ratio (69% [MPC-D100/764]; Dewaele, 2015) further suggesting the potential for quadrupedality at hatching based on limb length proportions. It is important to keep in mind that the estimated length of the UCMP 128181 forelimb, as with hatchlings of other taxa, may underrepresent the total relative forelimb length because of extensive cartilage caps at the epiphyses of limb bones in perinates of this size (Horner and

Currie, 1994). This estimate is also based on the forelimb-hindlimb relationships of ontogenetically larger and more osteologically mature individuals that likely had relatively smaller cartilage caps (e.g. Bonnan et al., 2010; Holliday et al., 2010).

The appendicular skeleton of hadrosaurids increases in length by an order of magnitude or more through growth (Table 1-6). Our analysis of Edmontosaurus encompasses a broad ontogenetic range with a femur length range of 148–1,242 mm and body mass range of 14–6,922 kg. This is comparable to the virtually complete growth series known for Maiasaura (Horner et al. 2000;

Woodward et al., 2015) and Hypacrosaurus (Horner and Currie 1994). Overall, the relative growth of the limbs across this wide ontogenetic spectrum varies marginally from isometry and

27 does not necessitate a gait shift as the differences in limb proportions dictate in other non-avian dinosaur taxa such as Psittacosaurus (Zhao et al., 2013) and Massospondylus (Reisz et al.,

2005). The relative proportion between the total lengths of the forelimb to hindlimb is maintained from juveniles (LACM 23504) to adults, and we can predict a similar ratio in nestlings. Likewise, the relationship between the minimum diaphyseal circumferences of the humerus and femur are also maintained through ontogeny, at least from the juvenile stage, which differs from the predictions of Dilkes (2001). The weak positively allometric trend observed in the ulna (comp. 9) is likely a result of the ontogenetic lengthening of the olecranon process, which has been shown to be characteristic of quadrupedality in ornithischian dinosaurs

(Maidment and Barrett, 2014). This may provide some support for an ontogenetic shift towards quadrupedality. However, it may also be a response to posterior shifts in the distribution of mass across the body with growth, rather than accommodating a permanent gait shift. To further test this hypothesis, it would be beneficial to incorporate variables from the pelvic girdle and other regions of the skeleton, but the poor preservation of these elements across the entire dataset makes it difficult to do so. However, the current data illustrates that nestlings were anatomically capable of fully quadrupedal locomotion and provide no compelling evidence to support an ontogenetic gait shift in Edmontosaurus. Results from these analyses are consistent with trackway evidence for juvenile hadrosaurids from Denali National Park, Alaska (Fiorillo and

Tykoski, 2016). The estimated size of the smallest individuals (~165 cm total body length) that were definitively walking in a quadrupedal gait was intermediate between UCMP 128181 and

LACM 23504 (Fiorillo and Tykoski, 2016), suggesting even at nestling size, hadrosaurids engaged in quadrupedal locomotion.

1.9 Conclusion

UCMP 128181 is the first occurrence of a baby dinosaur skeleton from the intensely sampled

Hell Creek Formation and greatly expands the known ontogenetic range for Edmontosaurus as the smallest end-member. Using the previously established categorization of hadrosaurid growth stages (Horner et al., 2000), UCMP 128181 represents a late nestling. Across Edmontosaurus ontogeny, bivariate morphometric comparisons reveal the tested forelimb and hindlimb elements exhibit a predominantly isometric growth pattern, especially in the hindlimb. This indicates

Edmontosaurus was capable of quadrupedal locomotion from the time of hatching. Bipedality was the primitive condition in dinosaurs, but quadrupedality evolved secondarily and independently in many dinosaur groups (Maidment and Barret, 2014). Studying this major gait shift is essential because it can help assess the evolutionary origin and requirements of quadrupedality. In addition, ontogenetic shifts in gait are interesting because they are highly unusual among terrestrial vertebrates. Future studies will incorporate osteohistology and biomechanics to supplement these allometric analyses and further test the proposed gait shift hypothesis in hadrosaurs.

1.10 Acknowledgments

Access to specimens was facilitated by N. Carroll, M. Currie, P. Holroyd, M. Goodwin, C.

Mehling, D. Pagnac, K. Seymour, and K. Shepherd. Big thanks to many across the globe that helped gather measurements and confirm locality information: D. Brinkman, N. Campione, R.

Carr, N. Carroll, J. Eberle, J. Mallon, A. Mann, A. McGee, B. Roach, J. Scannella, V. Schneider,

H. Seyler, T. Sonoda, and M. Whitney. Comments from R. Butler, A. Farke, D. McLennan, P.

O’Connor, and an anonymous reviewer greatly enhanced the manuscript. We thank C. A.

Masnaghetti (artist) and N. Turinetti from Saurian and Urvogel Games, LLC for working with us to design cover art associated with this article. We thank the Twitchell family for their long-term support of field work by the UCMP and crews on and around their ranch. D. Melton and G.

Liggett of the Bureau of Land Management Office facilitated access to land under their management. We thank the M. Thomas family who supported Harley in the field during the collection of UCMP 128181. And most importantly, we thank the late H. Garbani, a long-term field associate and friend of the UCMP, who passed away in 2011. The nestling skeleton described in this paper is but one of a number of significant discoveries by Harley and his keen eyes and passion for hunting dinosaur bones over four decades working with W. Clemens and

UCMP field crews.

1.11 Funding

This work was supported by the University of California Museum of Paleontology Doris O. and

Samuel P. Welles Research Fund (to M. W.), a Natural Sciences and Engineering Research

Council of Canada Discovery Grant RGPIN 355845 (to D. C. E.), a Royal Ontario Museum

Department of Natural History Fieldwork Grant (to D. C. E.), N. Myrvold in support of the Hell

Creek Project III (to M. B. G.), and the University of California Museum of Paleontology (to M.

B. G.)

1.12 Tables

Table 1-1. UCMP 128181 vertebral column measurements (mm). Numbering corresponds to actual location along vertebral column (Fig. 1-2, 1-3). Abbreviations: c, caudal; d, dorsal; s, sacral. *Length measurements are added because separation cannot be definitively distinguished.

Length Height

Vertebra Block Dorsal Middle Ventral Anterior Middle Posterior

d8 Main 15.9 15.6 15.1 9.1 7 9.6

d9 Main 15 14.4 13.7 10 7.3 7.6

d10 Main 15 14.3 15.3 > 8.5 7.1 6.8

d11 Main 15.4 15 15.4 9.9 7.1 8.2

d12 Main 15.5 16.7 16 9.4 8.1 8.2

d13+d14* Main 28* 29.8* - > 8 - 9

s6 Main - 11.2 > 9.2 - - 10.4

s7 Main 12 10.9 11.9 10.2 8.6 9.7

Counterpart > 9.6 11.7 10.7 11.6 > 9.5 13

s8 Main 10.8 10.3 10.5 9.5 8.3 9.1

Counterpart 11.4 10.6 10.8 14 13.8 13.8

s9 Main 9.6 9.5 10.1 9.6 8.2 9.5

Counterpart 9.2 9.5 10.2 13.8 13.1 13.8

c1 Main 9.2 8.2 9.3 9.3 8.6 9.3

Counterpart 7.9 8.4 8.3 12.7 11.4 12.8

c2 Main 8.7 8 8.4 9.7 8.8 9.8

Counterpart 7.9 7.9 8.5 12.3 10.9 12.1

c3 Main 8.5 8.1 8.6 10.3 10 11

Counterpart 7.7 7.6 8 12.2 11.6 11.6

c4 Main 7.9 7.5 7.8 11.3 9.3 10.3

30 31

Counterpart 7.9 7.3 7.9 11.7 10.4 12.5 c5 Main 7.7 6.5 7.1 9.7 9.1 9.4

Counterpart 6.7 7.1 7.4 10.8 9.8 10.8 c6 Main 5.5 5.4 5.4 9.6 9.3 10.5 c7 Main 5.5 5.2 6.2 10.5 8.9 10.4 c8 Main - 5.2 5.7 10.1 - -

Table 1-2. UCMP 128181 appendicular skeleton measurements (mm). eEstimated length. hHalf circumference.

Element Side Measurement Index (mm)

Scapula R Blade height 30.7

Neck height 16.4

Ilium R Total length > 105

Pubis R Total length > 129

Pubic blade to acetabular margin length 75.3

Pubic blade height - distal 25.3

Pubic blade height - minimum 114

Ischium L Total length 137

Femur R Total length 144

Minimum circumference 30h

Midshaft diameter - maximum 19

Midshaft diameter - minimum 15.5

Medial condyle - anteroposterior width 33.2

Fourth trochanter length 19.3

Fourth trochanter width 9.9

L Total length 150

Minimum circumference 30h

Lateral condyle - anteroposterior width 31.4

Fourth trochanter length 18

Tibia Total length 135.9

R Proximal width 39.5

Midshaft width - minimum 9.9

Fibula Total length 113 R Distal head width 8.9

Metatarsal II Total length > 41.7

Proximal width 8.2 L Distal width 13e

Shaft width - minimum 7.1

Metatarsal III Total length 56.6

Proximal width 14.5 L Distal width 17.1

Shaft width - minimum 10

Metatarsal IV Total length > 49.4

Proximal width 10.3 L Shaft width - maximum 9.6

Shaft width - minimum 4.2

Table 1-3. Standard Major Axis (SMA) results from the bivariate morphometric analyses of

appendicular element variables against total femur length (x). Regression formulas expressed as

ln(y) = mln(x) + b. Positive or negative allometry is considered when the slope of the lines are

significantly different from a slope of 1, as indicated by the 95% confidence intervals. *no

significant correlation between variables (two tailed t-test; p > 0.05).

Slope Intercept Comparison (y) Sample N (m) 95% CI m (b) 95% CI b R2 Trend

1. Scapula All - UCMP 17 0.990 0.79 1.24 -0.127 -1.83 1.24 0.835 iso Length E. annectens 12 1.016 0.77 1.33 -0.298 -2.49 1.37 0.848 iso

E. regalis 5 1.090* 0.48 2.49 -0.864 -10.74 3.45 0.746 iso

2. Scapula Blade All 16 0.954 0.85 1.07 -1.426 -2.22 -0.71 0.959 iso Height All - UCMP 15 1.243 0.98 1.57 -3.435 -5.69 -1.64 0.846 iso

E. annectens 12 0.960 0.84 1.09 -1.454 -2.36 -0.66 0.965 iso

- UCMP 11 1.304 1.01 1.68 -3.834 -6.43 -1.82 0.885 pos

E. regalis 4 1.364* 0.35 5.26 -4.355 -31.81 2.77 0.651 iso

3. Scapula Neck All 17 1.094 0.95 1.26 -2.718 -3.87 -1.72 0.932 iso Height All - UCMP 16 1.277 0.91 1.80 -3.992 -7.63 -1.41 0.625 iso

E. annectens 11 1.123 0.94 1.34 -2.871 -4.33 -1.65 0.944 iso

- UCMP 10 1.386 0.88 2.19 -4.687 -10.23 -1.18 0.662 iso

E. regalis 6 1.505 0.93 2.44 -5.700 -12.31 -1.63 0.868 iso

4. Humerus All - UCMP 17 1.074 0.94 1.23 -1.115 -2.21 -0.16 0.938 iso Length E. annectens 12 1.090 0.92 1.29 -1.219 -2.61 -0.04 0.941 iso

E. regalis 5 1.369 0.77 2.42 -3.224 -10.68 0.99 0.892 Iso

5. Humerus All - UCMP 11 0.958 0.73 1.26 -0.930 -3.05 0.68 0.862 iso Deltopectoral Crest Length E. annectens 7 0.968 0.66 1.43 -1.004 -4.18 1.15 0.879 iso

E. regalis 4 0.793* 0.15 4.23 0.237 -24.05 4.79 0.283 iso

6. Humerus All - UCMP 10 1.141 0.96 1.36 -3.013 -4.55 -1.73 0.953 iso Deltopectoral Crest Width E. annectens 6 1.036 0.79 1.36 -2.310 -4.55 -0.61 0.960 iso

E. regalis 4 1.104* 0.42 2.93 -2.713 -15.67 2.18 0.860 iso

7. Humerus All - UCMP 14 1.231 0.96 1.58 -3.125 -5.52 -1.25 0.842 iso Circumference E. annectens 11 1.283 0.94 1.75 -3.470 -6.66 -1.12 0.828 iso

E. regalis 3 1.803* 0.61 5.32 -7.234 -32.19 1.23 0.989 iso

8. Radius Length All - UCMP 14 1.135 0.92 1.40 -1.618 -3.46 -0.12 0.888 iso

E. annectens 9 1.069 0.82 1.39 -1.179 -3.42 0.54 0.910 iso

E. regalis 5 0.704* 0.24 2.09 1.472 -8.35 4.77 0.485 iso

9. Ulna Length All - UCMP 15 1.229 1.01 1.50 -2.160 -4.03 -0.63 0.890 pos

E. annectens 10 1.120 0.87 1.45 -1.435 -3.68 0.30 0.900 iso

E. regalis 5 0.942 0.44 2.03 -0.082 -7.78 3.49 0.788 iso

10. Metacarpal All - UCMP 11 1.017 0.73 1.45 -1.530 -4.51 0.56 0.773 iso III Length E. annectens 7 1.049 0.64 1.72 -1.723 -6.33 1.09 0.800 iso

E. regalis 4 1.529* 0.42 5.55 -5.197 -33.61 2.63 0.696 iso

11. Femur All 18 1.025 0.92 1.14 -1.081 -1.84 -0.39 0.962 iso Circumference All - UCMP 17 1.194 0.93 1.53 -2.252 -4.56 -0.45 0.795 iso

E. annectens 14 1.034 0.93 1.15 -1.131 -1.88 -0.46 0.973 iso

- UCMP 13 1.257 0.98 1.61 -2.667 -5.11 -0.76 0.857 iso

E. regalis 4 1.329* 0.26 6.81 -3.270 -41.93 4.28 0.344 iso

12. Tibia Length All 22 0.985 0.93 1.04 -0.022 -0.40 0.33 0.987 iso

- UCMP 21 1.030 0.89 1.19 -0.336 -1.42 0.60 0.914 iso

E. annectens 16 0.980 0.93 1.03 0.007 -0.32 0.32 0.993 iso

All - UCMP 15 1.014 0.88 1.17 -0.226 -1.30 0.70 0.943 iso

E. regalis 6 1.122* 0.51 2.45 -0.982 -10.36 3.31 0.612 iso

13. Tibia All - UCMP 13 1.157 0.98 1.36 -2.232 -3.66 -1.02 0.938 iso Circumference E. annectens 9 1.154 0.90 1.48 -2.207 -4.43 -0.47 0.922 iso

E. regalis 4 1.376* 1.17 1.62 -3.789 -5.53 -2.31 0.997 pos

14. Fibula All 20 1.030 0.98 1.09 -0.405 -0.79 0.04 0.988 iso Length All - UCMP 19 0.971 0.84 1.13 0.005 -1.09 0.95 0.913 iso

E. annectens 15 1.033 0.98 1.09 -0.424 -0.83 -0.04 0.991 iso

- UCMP 14 0.982 0.83 1.16 -0.071 -1.33 0.99 0.926 iso

E. regalis 5 0.864* 0.36 2.06 0.764 -7.61 4.28 0.716 iso

15. Metatarsal III All 13 0.921 0.85 1.00 -0.577 -1.10 -0.09 0.985 neg Length All - UCMP 12 0.986 0.79 1.23 -1.028 -2.72 0.33 0.900 iso

E. annectens 8 0.924 0.83 1.03 -0.597 -1.33 0.06 0.987 iso

- UCMP 7 1.028 0.73 1.44 -1.312 -4.15 0.71 0.910 iso

E. regalis 5 0.732* 0.31 1.74 0.753 -6.37 3.74 0.714 iso

Table 1-4. Standard Major Axis (SMA) results from the bivariate morphometric analyses of

circumference, combined limb length, and intra-bone comparisons. Regression formulas

expressed as ln(y) = mln(x) + b. Positive or negative allometry is considered when the slope of

the lines are significantly different from a slope of 1, as indicated by the 95% confidence

intervals. *no significant correlation between variables (two tailed t-test; p > 0.05).

Comparison

(x : y) Sample N Slope (m) 95% CI m Intercept (b) 95% CI b R2 Trend

16. Hindlimb All - UCMP 9 1.048 0.86 1.28 -0.894 -2.66 0.56 0.951 iso Length : Forelimb Length E. annectens 5 1.046 0.67 1.64 -0.883 -5.41 2.01 0.936 iso

E. regalis 4 0.959 0.57 1.62 -0.194 -5.34 2.86 0.968 iso

17. Femur+Tibia All - UCMP 13 1.069 0.91 1.25 -1.092 -2.50 0.11 0.941 iso Lengths : Humerus+Radius E. annectens 8 1.065 0.81 1.40 -1.069 -3.58 0.84 0.923 iso Lengths E. regalis 5 0.882 0.83 0.93 0.350 -0.05 0.72 0.999 neg

18. Femur All - UCMP 14 1.025 0.80 1.31 -0.754 -2.44 0.57 0.849 iso Circumference : Humerus E. annectens 11 1.019 0.79 1.32 -0.735 -2.55 0.66 0.879 iso Circumference E. regalis 3 0.599* 0.04 9.13 1.911 -50.32 5.34 0.643 iso

19. Femur All - UCMP 14 1.008 0.77 1.32 -0.268 -2.14 1.16 0.813 iso Circumference : Tibia Circumference E. annectens 10 0.974 0.73 1.30 -0.074 -2.00 1.37 0.873 iso

E. regalis 4 1.035* 0.20 5.31 -0.404 -26.48 4.68 0.343 Iso

20. Scapula Length : All - UCMP 15 1.286 1.04 1.60 -3.486 -5.57 -1.81 0.869 pos Scapula Blade Height E. annectens 11 1.306 1.04 1.63 -3.599 -5.80 -1.84 0.910 pos

E. regalis 4 1.943* 0.48 7.93 -8.032 -49.02 2.01 0.602 iso

21. Scapula Length : All - UCMP 17 1.300 0.92 1.84 -3.900 -7.51 -1.35 0.591 iso Scapula Neck Height E. annectens 12 1.339 0.86 2.08 -4.137 -9.08 -0.95 0.587 iso

E. regalis 5 1.312* 0.59 2.92 -4.050 -14.95 0.86 0.768 iso

22. Humerus Length All - UCMP 16 1.189 0.94 1.51 -2.094 -4.14 -0.48 0.821 iso : Humerus Circumference E. annectens 13 1.227 0.93 1.62 -2.324 -4.79 -0.45 0.821 iso

- E. regalis 3 1.811* 0.11 29.60 -6.188 4.86 0.590 iso 186.65

23. Humerus All - UCMP 12 0.926 0.71 1.20 -0.144 -1.91 1.21 0.857 iso Length: Humerus Deltopectoral Crest E. annectens 8 0.922 0.65 1.30 -0.128 -2.52 1.56 0.876 iso Length E. regalis 4 0.616* 0.14 2.70 1.870 -11.55 4.93 0.533 Iso

24. Humerus All - UCMP 12 1.126 0.99 1.28 -2.213 -3.16 -1.37 0.969 iso Length: Humerus Deltopectoral Crest E. annectens 8 1.080 0.88 1.25 -1.936 -3.01 -0.55 0.970 iso Width E. regalis 4 0.998* 0.28 3.58 -1.356 -18.17 3.33 0.704 iso

11. Femur Length : All 18 1.025 0.92 1.14 -1.081 -1.84 -0.39 0.962 iso Femur Circumference All - UCMP 17 1.194 0.93 1.53 -2.252 -4.56 -0.45 0.795 iso

E. annectens 14 1.034 0.93 1.15 -1.131 -1.88 -0.46 0.973 iso

- UCMP 13 1.257 0.98 1.61 -2.667 -5.11 -0.76 0.857 iso

E. regalis 4 1.329* 0.26 6.81 -3.270 -41.93 4.28 0.344 iso

25. Tibia Length : All - UCMP 15 1.185 0.97 1.44 -2.256 -4.00 -0.83 0.892 iso Tibia Circumference E. annectens 11 1.197 0.99 1.45 -2.329 -4.02 -0.93 0.936 iso

E. regalis 4 1.423* 0.31 6.50 -3.923 -39.06 3.76 0.488 iso

Table 1-5. Estimated OLS regression values for UCMP 128181 from comparisons using femur

length as the standard variable (Supplementary Table S1-2). Percent error was calculated using a

ratio of the actual UCMP 128181 measurement and the OLS estimated value.

UCMP Edmontosaurus - E. annectens - UCMP Element Variable 128181 All UCMP 128181 128181

OLS % Error OLS % Error OLS % Error

Scapula total length - - - 146.10 - 138.98 -

blade height 31 29.29 5.85% 19.44 59.45% 16.92 83.24%

neck height 16.5 16.71 -1.28% 18.30 -9.83% 15.28 7.97%

Humerus total length - - - 75.00 - 73.03 -

deltopectoral crest length - - - 47.34 - 46.21 -

deltopectoral crest width - - - 15.57 - 18.25 -

minimum circumference - - - 25.19 - 23.66 -

Radius total length - - - 65.63 - 70.47 -

Ulna total length - - - 61.47 - 71.75 -

Metacarpal III total length - - - 44.30 - 41.62 -

Femur total length 148 ------

minimum circumference 60 58.99 1.71% 52.56 14.16% 44.24 35.62%

Tibia total length 136 135.74 0.19% 134.10 1.42% 133.68 1.73%

minimum circumference - - - 37.28 - 38.27 -

Fibula total length 113 116.11 -2.68% 140.31 -19.46% 135.51 -16.61%

Metatarsal III total length 57 56.68 0.56% 54.39 4.81% 45.80 24.45%

Table 1-6. Total femur length measurements (mm) of hadrosaurid ontogenetic stages as defined by Horner et al. (2000), unless otherwise noted by an additional citation for which the original categorization was followed. Data were collected by the authors first-hand and from published literature. 1Horner and Currie, 1994; 2Horner et al., 2000; 3Dewaele et al., 2015; 4Maryańska and

Osmólska, 1984.

Taxon Size-class Specimen # Femur (mm)

Edmontosaurus Early nestling - -

Late nestling UCMP 128181 148

Early juvenile - -

Late juvenile LACM 23504 567

Subadult CMNH 10178 910

Adult AMNH 5730 1148

Hypacrosaurus1 Embryonic MOR 562 80

Nestling MOR 548 168-235

Juvenile MOR 35 600

Subadult MOR 553 870

Adult MOR 549 1050

Maiasaura2 Early nestling YPM-PU 22432 70

Late nestling YPM-PU 22400 120

Early juvenile YPM-PU 22472 180

Late juvenile MOR-005JV 500

Subadult MOR-005SA 680

Adult MOR-005A 1000

Saurolophus Embryonic3 MPC-D100/764 43.5

Adult4 PIN 551-8 1200

1.13 Figures and Figure Captions

Figure 1-1. Sandstone Basin UCMP locality V80092. A, geographic map of Montana with the location where UCMP 128181 was discovered represented by a star; B, 1983 field photograph with UCMP research paleontologist J. Howard Hutchison for scale; C, 2016 field photograph.

41 42

Figure 1-2. Main block of UCMP 128181 Edmontosaurus cf. annectens skeleton. A, specimen photo; B, digital outline of bone/impressions. Major bone elements are labeled along with orientation. Vertebrae correspond with actual location along vertebral column. C, size of UCMP

128181 compared with the known ontogenetic series of Edmontosaurus cf. annectens.

Silhouettes by D. Dufault. Abbreviations: c, caudal vertebra; d, dorsal vertebra; s, sacral vertebra; (l), left; (r), right. Scale bars equal 10 cm for A and B and 1 m for C.

Figure 1-3. Counterpart of UCMP 128181 Edmontosaurus cf. annectens skeleton. A, specimen photo; B, digital reconstruction of bone/impressions. Major bone elements are labeled along with orientation. Vertebrae correspond with actual location along vertebral column. Abbreviations: c, caudal vertebra; MT, metatarsal; s, sacral vertebra; (l), left; (r), right. Scale bars equal 10 cm.

Figure 1-4. Anterior half of UCMP 128181 main block. A, overview containing dorsal ribs; B, close-up of right scapula. Scale bars equal 5 cm.

Figure 1-5. Tail impressions of UCMP 128181. A, main block; B, counterpart. Scale bars equal

5 cm.

Figure 1-6. Pelvic girdles of UCMP 128181. A, main block; B, close-up of right pubis; C, counterpart. Scale bars equal 5 cm.

Figure 1-7. Major hind limb elements of UCMP 128181. A, left femur from counterpart; B, right femur from main block; C, right tibia, fibula, and astragalus from main block. Scale bars equal 4 cm.

Figure 1-8. Right metatarsals of UCMP 128181 main block. Left-most is metatarsal II. Scale bar equals 4 cm.

Figure 1-9. Bivariate allometric results. SMA regressions for a variety of appendicular measurements against femur length (A–D) or combined hindlimb length (E). A, total lengths of forelimb elements; B, scapular and humeral variables; C, total lengths of hindlimb elements; D, minimum diaphyseal circumferences using the ‘ALL - UCMP’ samples to maintain consistency, estimated UCMP 128181 value from digital cross-section was included in figure for visual comparison only; E, combined forelimb versus hindlimb lengths with 95% confidence intervals;

F, overall results of most inclusive SMA regression analyses, symbol corresponds with slope (m) and vertical bars correspond with the upper and lower bounds of 95% confidence intervals (CI) of the slope (m). SMA statistics are presented in Tables 1-3 and 1-4.

1.14 Supplementary Tables

Supplementary Table S1-1. Edmontosaurus measurements used in bivariate analyses. All measurements in mm. Abbreviations: Scap, scapula total length; ScapBH, scapula blade height;

ScapNH, scapula neck height; Hum, humerus total length; HumC, humerus minimum diaphyseal circumference; HumDCL, humerus deltopectoral crest length; HumDCW, humerus deltopectoral crest width; Rad, radius total length; H+R, combined total length of humerus and radius; Uln, ulna total length; MetC3, metacarpal III total length; Forelimb, combined total length of humerus, radius, and metacarpal III; Fem, femur total length; FemC, femur minimum diaphyseal circumference; Tib, tibia total length; TibC, tibia minimum diaphyseal circumference; Fe+T, combined total length of femur and tibia; Fib, fibula total length; MetT3, metatarsal III total length; Hindlimb, combined total length of femur, tibia, and metatarsal III.

Estimated circumferences for the humerus and tibia of UCMP 128181 are first listed using the femur length as the reference datum and then the femur circumference. *estimated based on minimum and maximum diameters. **estimated using OLS regressions data. ***estimated using half circumference from digital cross section.

59 60

Specimen Species Scap ScapBH ScapNH Hum HumC HumDCL HumDCW Rad H+R Uln MetC3 Forelimb Fem FemC Tib TibC Fe+T Fib MetT3 Hindlimb Source

AMNH 5730 E. annectens 810 200 130 680.5 250.5 300 - 621.5 1302 698 314 1616 1148 512.3 968 381 2116 929 407.5 2523 N. Campione

AMNH 5879 E. annectens - - - 635 275 - 168 ------968 388 - 905 - - M. Wosik

AMNH 5886 E. annectens ------1076 - 1010 - 2086 962 - - Prieto-

Márquez, 2014

CCM E. annectens ------875 337.5 755 - 1630 - - - M. Wosik disarticulated

CCM mount E. annectens 945 203 134 650 286 370 149 567 1217 652 266 1483 1152 490 - - - 920 375 - M. Wosik

CMN 8509 E. annectens 865 172 124 ------995 417.5 840 317 1835 - - - M. Wosik; J.

Mallon

CMNH 10178 E. annectens 704 137 115 469 191 ------910 330 802.5 285.5 1713 801 255 1968 A. McGee

DMNH 1493 E. annectens 935 - - 604.5 - 330 - 541.5 1146 604.5 - - 1035 459.5 879 - 1914 858 - - Carpenter,

1998

FPDM E. annectens 942.5 194 107.5 527.5 172.5 - - 450 977.5 490 215 1193 990 344 827.5 273 1818 807.5 - - T. Sonoda

LACM 23504 E. annectens 475 90 70 310 117.5 174.5 72 279 589 306 147 736 559 220 490 172 1049 463 193 1242 N. Carroll

MOR 2939 E. annectens 1000 252 180 672.5 273 - 163 585 1258 665 - - 1175 509 1035 400.5 2210 963.5 - - J. Scannella; R.

Carr

NCSM 23119 E. annectens 892 185.5 148 590 276 ------1051 - 970 - 2021 875 - - V. Schneider

SDSM 4917 E. annectens 820 162 130 560 236 320 128 485 1045 547 305 1350 1032 381 955 362.5 1987 895 340 2327 M. Wosik

SM R4050 E. annectens 885 - 123 530 267 295 130 495 1025 580 260 1285 - 460 885 355 - 770 320 - N. Campione;

60 61

M. Wosik

UCMP 128181 E. annectens 146** 31 16.5 75** 25/36** 54** 65.6** 65.6** 140.6 61.5** 44.3** 184.9 148 60*** 136 37/57** 284 113 57 341 M. Wosik

UCMP 137278 E. annectens - - - 515 196 268 123 - - 513 - - 995 425 870 293 1865 760 - - M. Wosik

USNM 2414 E. annectens 800 177.5 118.5 517.5 217.5 284.5 120 450 967.5 495 226 1194 1025 388.5 915 329 1940 815 345 2285 M. Wosik

UWBM E. annectens ------1201 - 971.6 - 2173 901.7 - - M. Whitney

YPM 2182 E. annectens 870 195 200 590 245 - - 550 1140 600 270 1410 1025 490 950 - 1975 890 323 2298 B. Roach; Lull

and Wright,

1942

CMN 2288 E. regalis - - 154 694 - - 175 665 1359 760 - - 1219 - 1160 - 2379 - - - M. Wosik; J.

Mallon

CMN 2289 E. regalis 1018 215 162 697.5 270 382 171 673 1371 775.5 262 1633 1243 532 1174 405 2417 1070 375 2792 N. Campione;

J. Mallon

CMN 8399 E. regalis 925 166 133 620 235 340 157 585 1205 661 272 1477 1140 374 950 361* 2090 890 345 2435 M. Wosik; J.

Mallon

NHMUK PV E. regalis 750 - 115 525 - 320 - 602.5 1128 660 230 1358 1030 - 900 - 1930 845 350 2280 D. C. Evans

R8927

ROM 801 E. regalis 980 228 143 670 291 330 177 637 1307 763 330 1637 1280 480 1010 430 2290 985 415 2705 M. Wosik

(5167)

ROM 867 E. regalis 845 173 109 ------990 422.5 910 300 1900 875 340 2240 M. Wosik

(5851)

Supplementary Table S1-2. Ordinary Least Squares (OLS) results from the bivariate

morphometric analyses of appendicular element variables against total femur length (x).

Regression formulas expressed as ln(y) = mln(x)+b. Positive or negative allometry is considered

when the slope of the lines are significantly different from a slope of 1, as indicated by the 95%

confidence intervals. *no significant correlation between variables (two tailed t-test; p > 0.05).

Slope Intercept Comparison (y) Sample N (m) 95% CI m (b) 95% CI b R2 Trend

1. Scapula All - UCMP 17 0.904 -1.07 2.00 0.465 0.68 1.13 0.835 iso Length E. annectens 12 0.936 -1.67 2.19 0.259 0.66 1.22 0.848 iso

E. regalis 5 0.942* -6.92 7.28 0.180 -0.07 1.95 0.746 iso

2. Scapula All 16 0.934 -2.05 -0.53 -1.291 0.82 1.04 0.959 iso Blade Height All - UCMP 15 1.143 -4.77 -0.72 -2.745 0.85 1.43 0.846 iso

E. annectens 12 0.943 -2.19 -0.49 -1.341 0.82 1.07 0.965 iso

All - UCMP 11 1.226 -5.60 -1.00 -3.300 0.89 1.56 0.885 iso

E. regalis 4 1.101* -19.79 14.79 -2.497 -1.35 3.55 0.651 iso

3. Scapula Neck All 17 1.056 -3.53 -1.39 -2.460 0.90 1.21 0.932 iso Height All - UCMP 16 1.010 -5.25 0.97 -2.139 0.56 1.46 0.625 iso

E. annectens 11 1.091 -4.01 -1.31 -2.658 0.89 1.29 0.944 iso

All - UCMP 10 1.128 -7.43 1.62 -2.908 0.47 1.78 0.662 iso

E. regalis 6 1.403 -10.32 0.36 -4.978 0.64 2.16 0.868 iso

4. Humerus All - UCMP 17 1.040 -1.90 0.14 -0.880 0.89 1.19 0.938 iso Length E. annectens 12 1.058 -2.28 0.29 -0.995 0.87 1.24 0.941 iso

E. regalis 5 1.293 -8.53 3.15 -2.689 0.47 2.12 0.892 iso

5. Humerus All - UCMP 11 0.889 -2.32 1.41 -0.454 0.62 1.16 0.862 iso Deltopectoral Crest Length E. annectens 7 0.908 -3.25 2.08 -0.587 0.52 1.30 0.879 iso

E. regalis 4 0.422* -11.56 117.27 2.855 -1.62 2.46 0.283 Iso

62 63

6. Humerus All - UCMP 10 1.114 -4.23 -1.41 -2.822 0.91 1.32 0.953 iso Deltopectoral Crest Width E. annectens 6 1.015 -4.14 -0.19 -2.167 0.73 1.30 0.960 iso

E. regalis 4 1.024* -11.07 6.78 -2.144 -0.23 2.28 0.860 iso

7. Humerus All - UCMP 14 1.130 -4.56 -0.28 -2.421 0.82 1.44 0.842 iso Circumference E. annectens 11 1.168 -5.44 0.10 -2.672 0.77 1.57 0.828 iso

E. regalis 3 1.793* -23.88 9.55 -7.166 -0.56 4.15 0.989 iso

8. Radius All - UCMP 14 1.069 -2.83 0.51 -1.160 0.83 1.31 0.888 iso Length E. annectens 9 1.019 -2.82 1.15 -0.837 0.73 1.31 0.910 iso

E. regalis 5 0.490* -3.58 9.55 2.983 -0.44 1.42 0.485 iso

9. Ulna Length All - UCMP 15 1.159 -3.38 0.03 -1.674 0.91 1.40 0.890 iso

E. annectens 10 1.063 -3.03 0.95 -1.039 0.77 1.35 0.900 iso

E. regalis 5 0.837 -4.97 6.30 0.666 0.04 1.63 0.788 iso

10. Metacarpal All - UCMP 11 0.894 -3.21 1.86 -0.678 0.53 1.26 0.773 iso III Length E. annectens 7 0.938 -4.67 2.75 -0.961 0.40 1.48 0.800 iso

E. regalis 4 1.275* -21.53 14.71 -3.407 -1.29 3.84 0.696 iso

11. Femur All 18 1.005 -1.67 -0.22 -0.946 0.90 1.11 0.962 iso Circumference All - UCMP 17 1.065 -3.42 0.70 -1.358 0.77 1.36 0.795 iso

E. annectens 14 1.020 -1.76 -0.32 -1.037 0.91 1.13 0.973 iso

All - UCMP 13 1.163 -4.20 0.15 -2.024 0.85 1.48 0.857 iso

E. regalis 4 0.779* -22.50 23.71 0.607 -2.50 4.05 0.344 iso

12. Tibia All 22 0.978 -0.34 0.39 0.023 0.92 1.03 0.987 iso Length All - UCMP 21 0.984 -1.03 0.99 -0.020 0.84 1.13 0.914 iso

E. annectens 16 0.976 -0.29 0.36 0.031 0.93 1.02 0.993 iso

All - UCMP 15 0.984 -1.02 0.98 -0.024 0.84 1.13 0.943 iso

E. regalis 6 0.877* -6.10 7.58 0.740 -0.09 1.85 0.612 Iso

13. Tibia All - UCMP 13 1.120 -3.30 -0.66 -1.979 0.93 1.31 0.938 iso Circumference E. annectens 9 1.108 -3.87 0.09 -1.892 0.82 1.40 0.922 iso

E. regalis 4 1.374* -5.38 -2.17 -3.774 1.15 1.60 0.997 pos

14. Fibula All 20 1.024 -0.74 0.01 -0.364 0.97 1.08 0.988 iso Length All - UCMP 19 0.928 -0.71 1.33 0.307 0.78 1.07 0.913 iso

E. annectens 15 1.029 -0.79 0.00 -0.394 0.97 1.09 0.991 iso

All - UCMP 14 0.945 -0.98 1.35 0.185 0.78 1.11 0.926 iso

E. regalis 5 0.730* -4.25 7.65 1.700 -0.12 1.58 0.716 iso

15. Metatarsal All 13 0.914 -1.04 -0.03 -0.531 0.84 0.99 0.985 neg III Length All - UCMP 12 0.935 -2.20 0.84 -0.678 0.72 1.15 0.900 iso

E. annectens 8 0.918 -1.25 0.14 -0.558 0.81 1.02 0.987 iso

All - UCMP 7 0.980 -3.42 1.45 -0.986 0.63 1.34 0.910 iso

E. regalis 5 0.618* -3.50 6.60 1.549 -0.10 1.34 0.714 iso

Supplementary Table S1-3. Ordinary Least Squares (OLS) results from the bivariate

morphometric analyses of circumference, combined limb length, and intra-bone variables.

Regression formulas expressed as ln(y) = mln(x)+b. Positive or negative allometry is considered

when the slope of the lines are significantly different from a slope of 1, as indicated by the 95%

confidence intervals. *no significant correlation between variables (two tailed t-test; p > 0.05).

Comparison Slope Intercept (x : y) Sample N (m) 95% CI m (b) 95% CI b R2 Trend

16. Hindlimb All - UCMP 9 1.022 -2.30 0.92 -0.691 0.81 1.23 0.951 iso Length : Forelimb Length E. annectens 5 1.012 -4.33 3.08 -0.624 0.53 1.50 0.936 iso

E. regalis 4 0.944 -4.17 4.03 -0.072 0.42 1.47 0.968 iso

17. Femur+Tibia All - UCMP 13 1.037 -2.16 0.46 -0.850 0.86 1.21 0.941 iso Lengths : Humerus+Radius E. annectens 8 1.023 -2.97 1.46 -0.756 0.73 1.32 0.923 iso Lengths E. regalis 5 0.882 -0.03 0.74 0.354 0.83 0.93 0.999 neg

18. Femur All - UCMP 14 0.945 -1.78 1.24 -0.270 0.69 1.19 0.849 iso Circumference : Humerus E. annectens 11 0.956 -1.96 1.25 -0.353 0.69 1.22 0.879 iso Circumference E. regalis 3 0.480* -25.20 30.47 2.638 -4.06 5.02 0.643 iso

19. Femur All - UCMP 14 0.909 -1.32 1.98 0.328 0.63 1.18 0.813 iso Circumference : Tibia E. annectens 10 0.910 -1.38 2.00 0.307 0.63 1.19 0.873 iso Circumference E. regalis 4 0.606* -13.37 17.80 2.214 -1.95 3.16 0.343 iso

20. Scapula All - UCMP 15 1.199 0.92 1.48 -2.899 -4.78 -1.02 0.869 iso Length : Scapula Blade Height E. annectens 11 1.246 0.95 1.54 -3.197 -5.17 -1.22 0.910 iso

E. regalis 4 1.508* -2.22 5.24 -5.054 -30.57 20.46 0.602 Iso

21. Scapula All - UCMP 17 1.000 0.54 1.46 -1.877 -4.96 1.20 0.591 iso Length : Scapula Neck Height E. annectens 12 1.026 0.42 1.63 -2.038 -6.11 2.03 0.587 iso

E. regalis 5 1.149* -0.01 2.31 -2.944 -10.85 4.96 0.768 iso

22. Humerus All - UCMP 16 1.077 0.79 1.37 -1.385 -3.22 0.45 0.821 iso Length : Humerus Circumference E. annectens 13 1.111 0.77 1.46 -1.592 -3.77 0.58 0.821 iso

E. regalis 3 1.391* -13.35 16.13 -3.458 -99.21 92.30 0.590 iso

23. Humerus All - UCMP 12 0.857 0.61 1.10 0.290 -1.27 1.85 0.857 iso Length: Humerus Deltopectoral E. annectens 8 0.862 0.54 1.19 0.244 -1.80 2.28 0.876 iso Crest Length E. regalis 4 0.450* -0.83 1.73 2.940 -5.30 11.18 0.533 iso

24. Humerus All - UCMP 12 1.108 0.97 1.25 -2.100 -2.99 -1.20 0.969 iso Length: Humerus Deltopectoral E. annectens 8 1.064 0.88 1.25 -1.832 -3.01 -0.65 0.970 iso Crest Width E. regalis 4 0.837* -0.81 2.49 -0.311 -11.06 10.44 0.704 iso

11. Femur Length All 18 1.025 0.92 1.14 -1.081 -1.84 -0.39 0.962 iso : Femur Circumference All - UCMP 17 1.194 0.93 1.53 -2.252 -4.56 -0.45 0.795 iso

E. annectens 14 1.034 0.93 1.15 -1.131 -1.88 -0.46 0.973 iso

- UCMP 13 1.257 0.98 1.61 -2.667 -5.11 -0.76 0.857 iso

E. regalis 4 1.329* 0.26 6.81 -3.270 -41.93 4.28 0.344 iso

25. Tibia Length : All - UCMP 15 1.120 0.89 1.35 -1.810 -3.39 -0.23 0.892 iso Tibia Circumference E. annectens 11 1.158 0.93 1.39 -2.065 -3.61 -0.52 0.936 iso

E. regalis 4 0.994* -2.10 4.09 -0.960 -22.37 20.45 0.488 iso

Chapter 2

Life history and paleoecology of hadrosaurid dinosaurs from the

Dinosaur Park Formation of Alberta, Canada, with implications for

population structure

Mateusz Wosik1, Kentaro Chiba1, François Therrien2, Donald B. Brinkman2, and David C.

Evans1,3

1Department of Ecology and Evolutionary Biology, University of Toronto, 100 Queen’s Park,

Toronto, Ontario, M5S 2C6, Canada, [email protected]

2Royal Tyrrell Museum of Paleontology, 1500 N Dinosaur Trail, Drumheller, Alberta, T0J 0Y0,

Canada, [email protected], [email protected]

3Department of Natural History, Royal Ontario Museum, 100 Queen’s Park, Toronto, Ontario,

M5S 2C6, Canada, [email protected]

2.1 Abstract

Previous research considered the Dinosaur Park Formation (DPF) of Alberta as an attritional, or time-averaged, assemblage; a size-frequency distribution of long bones collected from the DPF revealed three distinct size classes, indicating that DPF hadrosaurids attained near-asymptotic body size in under three years. This conflicted with osteohistological estimates of 6-8 years for penecontemporaneous hadrosaurids from the Two Medicine Formation (TMF) of Montana suggesting either extreme variation in hadrosaurid growth rates or poor performance of size- frequency distributions to accurately estimate ontogenetic age in attritional mass death assemblages.

We tested the validity of the proposed size-age relationship of hadrosaurids from the DPF by increasing the sample size and combining data from size-frequency distributions and long bone histology across multiple elements. The newly constructed size-frequency distribution revealed four relatively distinct size-frequency peaks that, when integrated with the osteohistological data, aligned with age. Interestingly, the yearling size class was heavily underrepresented in the size- frequency distribution. If not due to preservation, this suggests that either juvenile (< 2 years of age) hadrosaurids from the DPF had increased survivorship following an initially high nestling mortality rate or that yearlings were segregated from adults. A growth curve analysis revealed asymptotic body size was attained in 7 years, but maximum body size exhibited a high degree of variation, which is not unexpected in this multi-taxic assemblage. When compared with hadrosaurids from the TMF, growth rates of hadrosaurids from the DPF were faster by

69 approximately 2 years. The data suggest size-frequency distributions of attritional samples underestimate age and overestimate growth rates and should be paired with osteohistology to provide more accurate and precise interpretations.

2.2 Introduction

Hadrosaurs, commonly known as duck-billed dinosaurs, were the dominant large-bodied terrestrial herbivores in many Late Cretaceous ecosystems (Horner et al. 2004). They had a nearly global geographic distribution (Lund and Gates 2006; Prieto-Márquez 2010b), including latitudinal extremes (Case et al. 2000; Gangloff and Fiorillo 2010), and were one of the most diverse and abundant dinosaur groups (e.g. Horner et al. 2004; Prieto-Márquez 2010a, 2010b).

The current fossil record exceeds 60 distinct species including numerous articulated skeletons

(e.g. Horner et al. 2004; Prieto-Márquez 2010a) and monodominant bonebeds (e.g. Christians

1992; Horner et al. 2000; Colson et al. 2004; Lauters et al. 2008; Scherzer and Varricchio 2010;

Woodward et al. 2015; Ullmann et al. 2017) covering wide ontogenetic ranges, as well as eggs and embryos for some taxa (e.g. Dewaele et al. 2015; Horner and Makela 1979; Horner 1999;

Horner and Currie 1994). This makes hadrosaurs an ideal clade on which to conduct investigations of life history characteristics.

Pioneering work by Horner et al. (1999, 2000) investigated the growth of these animals using osteohistology, which is the study of bone tissues. One particular feature that can be observed in transverse cross-sections of limb bones is growth marks. These ‘tree-like’ growth rings, which are present in all major vertebrate groups (e.g. Peabody 1961; Halliday and Verrell 1988; de

Buffrenil and Castanet 2000; Chinsamy-Turan 2005; Bourdon et al. 2009; Woodward et al.

2011; Köhler et al. 2012), denote annual decelerations or complete cessations of bone growth and provide precise assignment of ontogenetic ages to individual fossil specimens. These growth marks enabled Cooper et al. (2008) to develop arithmetic modeling techniques to estimate the growth rate of hadrosaurids from the Two Medicine Formation (TMF) (Fig. 2-1) of Montana

(Campanian ~83–71 mya) and revealed that asymptotic adult body size was attained between six to eight years of age.

To investigate growth patterns of hadrosaurids from the Dinosaur Park Formation (DPF) (Fig. 2-

1) of Alberta, Brinkman (2014) considered the entire DPF as a single attritional, or time- averaged, assemblage and generated a size-frequency distribution of hadrosaurid long bones based on isolated elements and associated skeletons. Three distinct size-frequency peaks were identified and interpreted as discrete size classes. Two of these size-frequency peaks were attributed to juveniles and subadults, whereas the broad third size-frequency peak was inferred as a clustering of overlapping size classes of the largest individuals found within the DPF assemblage. Assuming a closely correlated relationship between size and age, this study suggested that hadrosaurids from the DPF attained asymptotic body size within three years of age, which conflicts with osteohistological estimates for the closely related and comparably sized

Maiasaura peeblesorum (Horner et al. 2000; Woodward et al. 2015) and Hypacrosaurus stebingeri (Horner et al. 1999; Cooper et al. 2008) from the TMF.

Taken together, these studies suggest either extreme variation among hadrosaurid growth rates or poor performance of size-frequency distributions to accurately estimate ontogenetic age in attritional mass death assemblages. Clarification of the biological meaning of the DPF size- frequency pattern is important not only because it has implications for understanding variation in hadrosaurid growth strategies, but may also provide further insight about taphonomic biases and

71 seasonal preservation patterns in the DPF system. The objectives of the present study were (1) to evaluate whether body size and ontogenetic age were strongly correlated in hadrosaurid dinosaurs and (2) to further test the hypothesis of a potentially rapid growth rate in hadrosaurids from the DPF relative to those from the TMF. Because Brinkman (2014) was limited to a small sample size, we considerably expanded the original dataset and subjected it to an osteohistological examination to independently assess ontogenetic age. To date, this is the first time that the inferred relationship between size and age classes has been vigorously tested by combining size-frequency distributions with osteohistology.

2.3 Materials and Methods

The sample size of hadrosaurid long bones from the Dinosaur Park Formation was increased from a total of 58 femora and tibiae (Brinkman 2014) to 417 across all six major limb bones from isolated elements and associated skeletons: 84 humeri, 39 radii, 43 ulnae, 92 femora, 111 tibiae, and 48 fibulae. Isolated elements in our dataset generally exhibited surface abrasions indicative of transport and were thus assumed to be from different individuals. Locality data were evaluated to eliminate specimens from the dataset that originated from outside of the DPF but were insufficient to distinguish between the upper and lower DPF “faunal zones” for the majority of specimens (Ryan and Evans 2005). Total length and minimum diaphyseal circumference measurements were gathered personally (MW) and from published literature

(Appendix 2-1). Linear measurements under 30 cm were taken with digital calipers, while those over 30 cm and all circumferences were taken using a fabric tape measure. Where complete data from left and right elements from the same specimen were available, the measurements were

72 averaged prior to analysis. Ontogenetic size classes were identified on the basis of Horner et al.

(2000) who defined ontogenetic growth stages in the hadrosaurid dinosaur Maiasaura peeblesorum based on osteohistological criteria, body size, and egg, nest, and adult associations.

Specimens for osteohistological sectioning were derived from the Royal Tyrrell Museum collections and additional specimens were collected from Dinosaur Provincial Park (Bonebed

50), Alberta, during a 2016 field season and accessioned at the Royal Tyrrell Museum.

2.3.1 Regression Analyses

In order to generate a combined size-frequency distribution of stylopodial and zeugopodial elements from the forelimb and hindlimb, a sample of associated skeletons (n = 25;

Supplementary Table S2-1) from the entire DPF dataset was analyzed using Standard (Reduced)

Major Axis (SMA) regressions for any potentially differentiating allometric trajectories between individual elements. Each variable was plotted against the reference datum, femur length. Femur length is an appropriate standard variable for this study because it is frequently used as a size proxy in allometric studies of the appendicular skeleton in terrestrial vertebrates, and unlike the forelimb, the hindlimb is typically used in locomotion in terrestrial vertebrates (e.g. Campione and Evans 2012). SMA regressions were used because they assume that both variables contain error from inaccurate measurements (Warton et al. 2006).

In addition, Ordinary Least Squares (OLS) regressions between the total length and minimum diaphyseal circumference of complete elements from the entire DPF dataset of each respective limb element were used to estimate the size of the corresponding variable for incomplete elements. The purpose of this was to include valuable data from incompletely preserved or obstructed limb bones (e.g. wall mounted skeletons) and subsequently increase the overall sample sizes used for each individual size frequency distribution.

Linear data were log-transformed prior to analysis using natural log (ln). SMA (Supplementary

Table S2-2) and OLS (Supplementary Table S2-3) regressions were used to determine the slopes, intercepts, 95% confidence intervals, and correlation coefficients for each comparison. Each comparison was then evaluated using two-tailed p-values using a significance level of 0.05 for correlation between variables. The results of each SMA regression were assigned as positively allometric (95% confidence interval of slope is greater than 1), negatively allometric (95% confidence interval of slope is less than 1), or isometric (95% confidence interval of slope includes 1). The regressions and statistical analyses were performed in R (R-Development-Core-

Team 2016) with the package ‘lmodel2’ (Legendre 2013).

2.3.2 Size-Frequency Distributions

Individual size-frequency distributions of total length and minimum diaphyseal circumference were generated in R (R-Development-Core-Team 2016) using the entire dataset for each respective limb element. For relative scale, ROM 845 (Corythosaurus casuarius) was used to represent a presumably morphologically adult-sized specimen with an approximate body length of 9.0 meters. This specimen was selected due to its near complete preservation with minimal deformation providing more accurate proportions of limbs for an adult individual and because of its high taxonomic abundancy relative to other hadrosaurids from the Dinosaur Park Formation

(Ryan and Evans 2005). The dataset used in Brinkman (2014) was reanalyzed and scaled to

ROM 845. The dataset for the combined size-frequency distribution in our study only considered isolated specimens to eliminate biases related to preservation (Brown et al. 2013b, 2013c) and selecting or ranking elements from associated skeletons.

Size-frequency distributions can be sensitive to the amount and size of bins. Therefore, an attempt to optimize bin size was made using a technique developed by Shimazaki and Shinomoto

(2007, 2010) that utilizes the mean integrated squared error (MISE), which is a measure of the goodness-of-fit of a histogram to the unknown rate. The cost function for each individual sample was assessed to find a range of optimum values. These ranges were then overlapped among all of the size-frequency distributions to find a range of overlapping values, which resulted in a general average of approximately 30 bins.

2.3.3 Osteohistology

A total of 35 isolated elements consisting of seven humeri, eight femora, and twenty tibiae from the TMP collections spanning the entire ontogenetic size range from nestlings to presumably mature adults were histologically thin-sectioned at the minimum diaphyseal circumference to assess ontogenetic age. The minimum diaphyseal circumference was selected (1) to maintain consistency of the sectioning location through ontogeny, (2) to correlate with body mass estimations (Campione and Evans 2012), and (3) to compare with previously published literature of other hadrosaurid taxa (Horner et al. 1999, 2000; Cooper et al. 2008; Freedman Fowler et al.

2015; Woodward et al. 2015). Specimens for histological sectioning were selected from each size-frequency peak based on the size of the minimum diaphyseal circumference to assess the correlation between size and age. Thin sections were made and imaged at the ROM

Palaeohistology Laboratory, and all molding and casting materials and thin-sections were deposited at TMP.

Ontogenetic series of thin-sections from the minimum diaphyseal circumference of humeri, femora, and tibiae were compared to assess the osteohistological differences through ontogeny for each element. Histological terminology follows that of Francillon-Vieillot et al. (1990).

Cross-polarized filters were used to diagnose the orientation of collagen fibers (e.g. lamellar, parallel-fibered, woven-fibered). Vascular orientation is used to describe how the long axes of

75 vascular canals are oriented in the bone matrix (e.g. longitudinal, radial, reticular, plexiform, laminar). Cyclical growth marks were diagnosed based on a variation or pause in the rate of bone growth and were used to determine the age and growth rates of sampled individuals. Lines of arrested growth (LAGs), a type of cyclical growth mark, were identified based on an attenuation or complete cessation in bone deposition, which would be visible along the circumference of the section. A zone represented the bone deposition region in between growth marks.

Prior to sectioning, specimens were mechanically prepared with pneumatic and hand tools to remove rock matrix and later followed by an inspection of external surfaces around the diaphyseal region for damage resulting from preparation, for which nothing substantial was seen.

Each specimen was measured and photographed. Three-dimensional models were generated using traditional molding and casting as well as photogrammetric (Agisoft PhotoScan) and laser scanning (ScanStudio) techniques.

Complete transverse cross-sectional pucks that contained the minimum diaphyseal circumference were extracted using a Well Diamond Wire Saw 9000 series or Buehler IsoMet 1000 Precision

Cutter low-speed saw depending on the size of the specimen. The pucks were molded and casted and casts were then reinserted into the original bone following the procedures of Wosik (in prep).

The pucks were completely embedded in Castolite polyester resin, grinded on a lapwheel, and polished on a glass block using a sequential grit series of 600 and 1000. They were then submerged in a sonic vibration bath to remove excess grit and allowed to air dry for 24 hours before being mounted on 2-3 mm thick plexi-glass slides with either PSI 122/124 resin for large specimens (diameter > 3 cm) or CA-40 cyanoacrylate (diameter < 3 cm). The blocks were cut away from the slide on the IsoMet, and subsequently ground down to an appropriate thickness using either a Hillquist Thin Sectioning Machine or grinding lap wheel based on size and

76 necessity. Complete cross-sectional slides were finished by hand polishing on a glass plate with

600 followed by 1000 silicon carbide grit and again bathed in a sonic bath.

Thin-section images were photographed at the Royal Ontario Museum Palaeohistology

Laboratory using a Nikon DS-Fi1 camera mounted to a Nikon AZ-100 microscope under plain- polarized and cross-polarized light. Images were processed and assembled using Nikon NIS-

Elements Basic Research 3.13 imaging software. Images were captured at various magnifications dependent on the size of the cross-section, 1280 x 960 resolution, 2-8 millisecond exposure, and set on Dynamic contrast with ≥ 40% overlap. Johnson & Johnson baby oil was added to the surface of each slide to increase optical clarity during imaging. Multiple images were taken for slides that exceeded the focal dimensions of the imaging stage and later stitched together using the File>Automate>Photomerge feature in Adobe Photoshop. Further processing of images (e.g. text, scale bars) was completed using Adobe Photoshop and Illustrator. Retrodeformation of histological images for elements suffering from taphonomic distortion (e.g. crushing, flattening) was performed digitally using Adobe Photoshop to account for a more accurate size and shape of cross-sectional areas.

2.3.4 Age Determination and Growth Modeling

The mid-diaphysis of tibiae preserves the most complete growth record in hadrosaurid dinosaurs

(Horner et al. 1999), but growth marks, herein considered to correspond with annual cycles or annuli (e.g. Köhler et al. 2012), can be progressively obliterated due to bone remodeling emanating from the expansion of the medullary region through ontogeny (Erickson 2016). In order to account for the entire growth history, age retrocalculation (Cooper et al. 2008) was performed on specimens with the longest growth record to identify any potentially missing growth marks, or growth years. Tibia circumference and body mass growth curves were

77 generated using Richards-family growth models (Lee and O’Connor 2013) in R (R-

Development-Core-Team 2016). Corrected Akaike Information Criterion (AICc) values were used to account for small sample sizes consisting of a single element for each taxon using R package ‘MuMIn’ (Bartoń 2017). Next, delta AICc (ΔAICc) and AICc weight values were calculated to obtain averaged models for each specimen (Burnham and Anderson 2002).

Obtaining an averaged model is important when AICc values of individual models are within ten

ΔAICc, which deems each individual model as plausible (Burnham and Anderson 2002). Finally, the retrocalculated ages obtained from the averaged models for each specimen were considered as the accurate and precise age of growth marks and applied in the tibia circumference and body mass growth curve analyses. An osteohistologically determined tibial hatchling circumference of

25 mm was used for each age retrocalculation model (Wosik et al. 2017c).

Each sampled tibia used to generate growth curves had attained asymptotic body size and provided a base to estimate body masses for each respective taxon using an interspecific equation for quadrupedal vertebrates (Campione and Evans 2012: Equation 1). The body mass equation requires the sum of humerus and femur minimum diaphyseal circumferences as a dependent variable, so the tibia circumferences were converted to the sum of humerus and femur circumferences based on associated skeletons from the DPF (n = 6, R2 = 0.99). The estimated values of the combined humerus and femur circumferences were cross-checked with associated skeletons of each respective taxon when available. Developmental Mass Extrapolation (DME)

(Erickson and Tumanova 2000) was then used to convert each growth mark circumference to body mass to account for deviations from the body mass equation for juvenile individuals. Age was also cross-checked via section-stacking of growth marks, or annuli, (Bybee et al. 2006) from the histological samples in this study whenever possible.

Transverse section periosteal surfaces (outer circumferences) and circumferences of growth marks were traced in Adobe Illustrator. Data for tibiae of hadrosaurids used for comparison were obtained from published literature for Maiasaura (MOR 758 NC-7-4-96-‘T46’; Woodward et al.

2015) and Hypacrosaurus (MOR 549; Cooper et al. 2008), whereas those for

Probrachylophosaurus (MOR 2919; Freedman Fowler and Horner 2015) were re-measured in

Adobe Illustrator after minor digital reconstruction of the original histological image to account for a more accurate size and shape of the transverse cross-sectional area. Freedman Fowler and

Horner (2015) interpreted LAG 8 in Probrachylophosaurus (MOR 2919) as a zone of one to five closely spaced lines, which is maintained herein for consistency and comparison.

2.4 Results

In order to assess life history characteristics of hadrosaurids from the DPF, a multi-taxic approach was undertaken due to the lack of a suitable monodominant hadrosaurid bonebed from the DPF (Eberth et al. 2014, Eberth 2015). The taxonomic diversity of resident hadrosaurids consisted of five genera, with each taxon reaching comparable adult size with approximate body lengths of 9.0–9.5 meters (Ryan and Evans 2005). Therefore, it is important to acknowledge that our results may be based on sample sizes consisting of multiple genera, similar to Brinkman

(2014) (Fig. 2-2A).

Of the 417 hadrosaurid limb bones measured for this study, 260 were classified as isolated belonging to separate individuals, and 157 were from a total of 34 associated skeletons. Twenty five of the 34 associated skeletons were taxonomically identifiable to the genus level, with 18 attributable to lambeosaurines and seven to hadrosaurines. Corythosaurus dominated the

79 lambeosaurine sample with 10 identifiable individuals. Complete total length and minimum diaphyseal circumference measurements were both preserved in 186 bones, and individually in

292 and 314 bones, respectively. The tibia generally exhibited the largest sample size for each categorical measure and had the best preservation of complete elements, which may be attributed to its robust morphology and thick cortical bone providing more resistance to taphonomic destruction (Horner et al. 1999). Nestling-sized hadrosaurid radii, ulnae, and fibulae (1) can be difficult to accurately identify and distinguish from similarly-sized elements of other penecontemporaneous dinosaur groups due to their simple morphologies and (2) were poorly represented, if at all, in our sample. Therefore, these poorly represented limb elements were excluded from further analyses in this study to avoid biases from uneven sampling, and they did not contribute to ontogenetic stages when the entire dataset was combined into a single size- frequency distribution.

2.4.1 Regression Analyses

Results of the SMA regression analyses (Supplementary Table S2-2, Supplementary Figure S2-

1A, B) indicated a largely isometric relationship of the limb length proportions through ontogeny, which allowed us to combine elements into a single size-frequency distribution.

Coefficients of determination (R2) associated with the regressions were generally high (> 0.86), correlation between variables was significant based on low p-values (p < 8.37e-05), slopes were constrained between 0.96–1.12, and confidence intervals contained 1.0 for all comparisons.

Sample sizes of the OLS regression analyses (Supplementary Table S2-3, Supplementary Figure

S2-1C, D) ranged from 22 (radius, fibula) to 40 (femur, tibia) individually complete specimens with stylopodial elements typically exhibiting larger sample sizes. All comparisons had high coefficients of determination (R2 > 0.86) and significant correlation between variables based on

80 low p-values (p < 5.41e-10). Therefore, estimation of incomplete elements could be confidently executed using the corresponding OLS regression model.

2.4.2 Size-Frequency Distributions

The combined size-frequency distribution (Fig. 2-2B) consisted of a total of 204 isolated hadrosaurid long bones from the DPF and revealed four relatively distinct size-frequency peaks along a generally positive parabolic distribution consistent with a long-term, time-averaged depositional origin (Olson 1957). The smallest size class included individuals that ranged from

~4–25% of the linear dimensions of ROM 845, with a size-frequency peak in the ~8–12% size range. Articular surfaces were poorly defined and the periosteal surface was punctuated with a porous surface texture due to the anastomosing of vascular canals providing independent morphological evidence for an early stage of ontogenetic development. Individuals in this size class would have had a body length ranging from 36–225 cm and corresponded with the nestling and early juvenile size classes as defined in Horner et al. (2000). It is important to note that the frequency of the first peak may be inflated as a result of collection bias favoring the ease of excavating small material. The second size class may contain two individual size-frequency peaks, but we interpreted this as a single size class that aligned with juvenile individuals that ranged from ~29-54% of the linear dimensions of ROM 845, with size-frequency peaks within the ~37-42% and ~46-50% size ranges, and body lengths of 261-486 cm. Articular surfaces were more defined but not yet rugose and surface textures followed a striated pattern that provided a base for micro-cracks to form from diagenetic processes. The third size class was consistent with subadults that ranged from ~58-75% of the linear dimensions of ROM 845, with a size- frequency peak in the ~67-71% size range, and body lengths of 522-675 cm. Periosteal surface textures ranged from striated to smooth, muscle attachment sites such as the fourth trochanter of

81 the femur (Dilkes 2000) were well developed, and articular surfaces exhibited rugose patterns.

The fourth size class was broader than the others and likely represented an accumulation of adult sized individuals attaining asymptotic body size. It ranged between ~75-121% of the linear dimensions of ROM 845, with a size-frequency peak within the 92-96% size range. Here, articular surfaces were fully developed with strong rugosities, periosteal surfaces were very smooth emitting a natural sheen, and robust muscle scars were clearly observed particularly along the mid-shafts of the humeri and femora.

When the dataset for the combined size-frequency distribution was partitioned into individual elements for total length and minimum diaphyseal circumference (Fig. 2-3), it became difficult to distinguish consistent size-frequency peaks across the individual size-frequency distributions.

Only in the humerus could three distinct size-frequency peaks and/or size classes be recognized for both the total length and minimum diaphyseal circumference size-frequency distributions

(Fig. 2-3A, B). Elements with smaller sample sizes (38 < N < 49; radius, ulna, fibula)

(Supplemental Figure S2-2) tended to only recover the adult cluster whereas the humerus, femur, and tibia (83 < N < 112) (Fig. 2-3) ranged between three to four potentially distinct size- frequency peaks and/or size classes.

2.4.3 Osteohistology

Neonate individuals exhibited a highly cancellous and disorganized matrix that primarily consisted of woven-fibered bone with localized concentrations of parallel-fibered bone (Fig. 2-

4A, B). Late nestlings began to transition to fibrolamellar bone with longitudinally or radially orientated vascular canals and preserved a narrow zone of reduced vascularity typically coinciding with a darkened band (Fig. 2-4E, G). This circumferentially oriented zone likely partitioned the embryonic and perinatal bone regions, although with some degree of

82 circumferential variation, and may be an osteohistological indicator of the hatching period

(Curry Rogers et al. 2016; Whitney et al. 2017; Wosik et al. 2017c). Early juveniles reflected the bone microstructure of late nestlings, but the medullary cavity had already expanded beyond and/or remodeled over the osteohistological indicator of hatching (Fig. 2-4C, D, F, H). Late juveniles were all composed of primary bone tissues exhibiting a relatively small medullary cavity surrounded by a highly vascularized complex of woven-fibered and parallel-fibered bone within the inner cortex (Fig. 2-4I-N). Secondary bone remodeling was minimal in the outer cortex except for the anterolateral border near a muscle attachment site which has been similarly observed in the ornithopods Tenontosaurus (Werning 2012) and Dysalotosaurus (Hübner 2012) and other hadrosaurids (Woodward et al. 2015; Freedman Fowler and Horner 2016). The vascular orientation of the outer cortex largely consisted of zonal bone, transitioning from reticular/plexiform into laminar vascular canal orientation within each zone (Fig. 2-4M, N). Sub- adults preserved the woven/parallel-fibered inner cortex but began to increase the area of the medullary cavity relative to the entire cross-sectional area (Fig. 2-4O-R). Adults had well developed secondary osteons, and the non-zonal outermost cortex was comprised almost solely of laminar oriented lamellar bone (Fig. 2-5A, C, D, F). Several of the largest individuals exhibited a pronounced stacking of LAGs in close proximity of one another near the periosteal surface (Fig. 2-5B, C, E, F) whereas late juveniles and sub-adults exhibited a more predominant zonal bone pattern with consistent shifts between reticular and laminar fibrolamellar bone (Fig.

2-4M, N, Q, R) than adults in the sample.

When comparing growth marks to the periosteal (outer) circumferences of the corresponding size class, the growth marks were offset and generally larger than the outer circumference of individuals belonging to a size-frequency peak (Fig. 2-6). Individuals sampled from the first size-frequency peak did not record any growth marks beyond the potential indicator of hatching.

Most of the sampled individuals from the second size-frequency peak only showed a layering of laminar oriented vascular canals near the periosteal surface (outer circumference) that was interpreted as the imminent deposition of a cyclical growth mark (Fig. 2-4M, N). However, several specimens preserved a growth mark nested closer to the inner cortex in addition to the layering of laminar oriented vascular canals near the periosteal surface (Fig. 2-4M, N). The extent at which the entire circumference of this growth mark was preserved ranged from complete (TMP 1979.014.0308 [tibia]) to partial (e.g. TMP 1993.036.0382 [humerus], TMP

1999.055.0350 [femur], TMP 1994.012.0872 [tibia]) due to a varying degree of secondary remodeling. Therefore, the second size-frequency peak represented hadrosaurids nearing two years of age. Individuals from the third size-frequency peak consistently preserved one growth mark in addition to the layering of laminar oriented vascular canals near the periosteal surface

(Fig. 2-4O-R). The circumferences of this growth mark corresponded with the outer circumferences of specimens from the second size-frequency peak (Fig. 2-6). When superimposing the growth mark from the second size-frequency peak onto sections of specimens from the third size-frequency peak, it placed deep within the medullary cavity region and was absent because it had already been obliterated through medullary cavity expansion (Fig. 2-6).

Therefore, the third size-frequency peak represented hadrosaurids nearing three years of age. The histological sample of the broad fourth size-frequency peak consisted only of humeri and tibiae and revealed that the size ranges of growth marks corresponding with each individual ontogenetic age began to overlap with size ranges of other ontogenetic ages, particularly in the tibia. A pronounced stacking of LAGs in close proximity of one another near the periosteal surface was present in several of the largest specimens, although in different places in the size range (e.g. TMP 2016.012.0193 [humerus], TMP 1979.014.0020, TMP 2016.012.0192 [tibia]) and resembled an external fundamental system (EFS) (Horner et al. 2000) or outer

84 circumferential layer (OCL) (Chinsamy-Turan 2005). The largest element (TMP 1979.012.0020

[tibia]; Fig. 2-5A, B, C) preserved a minimum of 15 growth marks.

2.4.4 Age Determination and Growth Modeling

Data related to parameter values of the averaged models is available in Table 2-1, whereas data for the individual models is in Supplementary Tables S2-4, 5, and 6 along with AICc scores.

Growth mark circumferences for the five tibiae are listed in Table 2-2 along with a summary of retrocalculated ages of each tibia and estimated body masses for each taxon obtained from the averaged models. Tibia circumference and body mass growth curves are presented in Figure 2-7.

Retrocalculation and growth modeling was restricted to tibiae so that our data could be compared with previously published growth rates of other hadrosaurids (Cooper et al. 2008; Freedman

Fowler and Horner 2015; Woodward et al. 2015). From our DPF sample, two tibiae preserved a substantial growth record that was suitable for growth modeling. Although the two tibiae could not be taxonomically identified beyond Hadrosauridae due to their isolated preservational nature, they are tentatively considered herein as separate species for the purposes of this study and based on their major differences in size and growth rate. With the addition of the three tibiae from other hadrosaurids, the total sample consisted of five individuals from at least four genera including both lambeosaurines and hadrosaurines. When reanalyzing the osteohistological record of

Probrachylophosaurus (MOR 2919; Freedman Fowler and Horner 2015), our growth mark circumference values were on average ~12% smaller, and an additional partially preserved growth mark was recovered from within the inner cortex of the section.

Retrocalculation revealed that the preserved growth mark record of each tibia was missing at least the first growth year (Table 2-2). Using the averaged tibia circumference growth models, the circumference of the growth mark corresponding with the first unrecorded annulus was

85 estimated to range between 62–100 mm dependent on the individual. Although our data generally corroborated the results presented for Maiasaura (Woodward et al. 2015) and

Hypacrosaurus (Cooper et al. 2008) on an individual model basis, the averaged model indicated one missing growth year for Maiasaura MOR 758 ‘T46’ and ten years for Hypacrosaurus MOR

549. To test this large discrepancy, we excluded the first recorded growth mark from the growth record of each of the five tibiae and reran the retrocalculation. When comparing these results to those from the unaltered growth records, retrocalculated ages were inconsistent between the two trials for most specimens (Table 2-1; see Supplementary Table S2-5 for complete data).

Retrocalculated ages of Maiasaura and Hypacrosaurus increased by nine and five years, respectively, whereas those for the two DPF tibiae did not change. The only altered model that could be considered as potentially recovering a consistent result was that of

Probrachylophosaurus because the retrocalculated age increased by ~1 year (0.61), compensating for the manually removed growth mark. These results demonstrated that at least the second growth mark of the early juvenile growth record was typically required to confidently estimate the accurate age of an individual hadrosaurid via growth modeling (Lee and O’Connor

2013; Chiba et al. 2015). In light of this, we attributed the discrepancy of Hypacrosaurus to its incomplete juvenile growth record, which drove the juvenile portion of the curve to become artificially extended. Therefore, our data for Hypacrosaurus was presented in this paper for consistency, but were not considered when making general statements about hadrosaurid growth and only contributed to discussions when appropriate comparisons could be made (i.e. asymptotic body size). Further mention of retrocalculated ages for the other four tibiae only considered the values obtained from the unaltered tibia circumference growth models.

In terms of body mass, the transition from growth acceleration to deceleration, or the growth inflection point (I), generally occurred between 2.36–2.79 years of age with the exception of

Maiasaura, which occurred at 1.40 years of age based on our reanalysis and had a maximum growth rate of 884 kg/yr between 1.65–2.65 years of age. Probrachylophosaurus had a similar maximum growth rate of 855 kg/yr between 3.64–4.64 years of age. TMP 1979.014.0020 had the largest maximum growth rate of our sample at 1227 kg/yr between 2–3 years of age rising to

1415 kg/yr between 3–4 years of age, whereas TMP 2016.012.0192 had the second largest maximum growth rate at 1095 kg/yr between 2.63–3.63 years of age. Using the unaltered averaged models (Table 2-1), the shape parameter m of the DPF growth curves resembled the shape of the von Bertalanffy model (m = 0.66) for TMP 2016.012.0192 and an intermediate between the von Bertalanffy and Gompertz models (m = 0.80) for TMP 1979.014.0020. The reanalyzed growth curves of Maiasaura and Probrachylophosaurus resembled an intermediate between the monomolecular and von Bertalanffy (m = 0.25–0.40) models. The tibiae from the

DPF had the smallest and largest asymptotic body mass estimates (A) (TMP 2016.012.0192,

3344 kg; TMP 1979.014.0020, 5338 kg), whereas Probrachylophosaurus was estimated at 4341 kg, and Maiasaura and Hypacrosaurus were estimated at ~4000 kg. Estimations for 95% asymptotic body mass ranged between 7–9 years of age, with both of the DPF specimens placing on the lower end of this range.

2.5 Discussion

Brinkman (2014) originally identified two well-defined subadult size-frequency peaks and a broad cluster of adult individuals consisting of two ill-defined size-frequency peaks. The first subadult size-frequency peak was interpreted as consisting of hatchling individuals, or late nestlings following the categorization of Horner et al. (2000), and concurred with our results

87 suggesting a high degree of hatchling/nestling mortality. The abundance of nestling individuals may have also been inflated as a result of collection bias favoring the ease of excavating small material. The second subadult size-frequency peak was interpreted as containing individuals of about 3.5 meters in body length and similar in size to a one-year old size class among other hadrosaurid dinosaurs (Varricchio and Horner 1993; Horner et al. 2000), whereas the third broad size-frequency peak consisted of overlapping adult size/age classes as growth slowed into adulthood. Using these data, Brinkman (2014) concluded that hadrosaurids from the DPF had a rapid growth rate, attaining adult size within three years of age. However, increasing the sample size revealed an additional size-frequency peak between Brinkman’s second and third size classes, indicating an initial overestimation of hadrosaurid growth rates by one year, and better recovered the spread and variation in the data. This additional size-frequency peak was similar in size to the smaller of the two ill-defined size-frequency peaks from the broad cluster of

Brinkman and aligned with the subadult stage (~4.7 m body length) of Horner et al. (2000) based on femur length.

Identification of what defines an adult individual can impact the interpretation of these analyses

(for an extensive discussion of this problem see Hone et al. 2016). Hadrosaurid dinosaurs possessed a variety of species-specific cranial specializations, particularly the expansion and/or modification of the nasal and premaxilla to form a wide diversity of crests (e.g. Lull and Wright

1942; Dodson 1975; Horner et al. 2004; Evans 2010; Campione and Evans 2011) as well as potential soft tissue structures (Bell et al. 2014). These cranial specializations developed progressively through ontogeny and were most prominent in adults providing an alternative to general body size of visually identifying individuals that were more mature (e.g. Dodson 1975;

Evans 2010; Campione and Evans 2011; Farke et al. 2013; McGarrity et al. 2013). Evans (2010) modified the categorization of ontogenetic stages from Horner et al. (2000) to reflect the cranial

88 series of hadrosaurid dinosaurs. Juveniles were referred to individuals with a skull length less than 50% of the maximum observed for individual taxa of lambeosaurines, subadults were defined as individuals possessing a skull length of 50–85%, and adults were over 85% (Evans

2010). When applying this method of ontogenetic categorization to our data, the proposed threshold of 85% based on cranial crest development placed beyond the additionally recovered size-frequency peak (Fig. 2-2), which was in agreement with the subadult stage of Horner et al.

(2000) based on femur length. Therefore, Brinkman (2014) oversimplified his interpretations and included subadult individuals (< 85%) within the broad ‘adult’ cluster that had not yet developed mature cranial crests.

Integrating the osteohistological growth mark data with the size-frequency distribution revealed a general correlation between size classes and ontogenetic growth stages (Fig. 2-8; also

Supplementary Figure S2-3). The sampled nestling individuals did not preserve any annual growth marks confirming that the first size-frequency peak was indeed correlated with nestling individuals that were under one year of age. However, the histology of juvenile specimens revealed a distinct growth mark (Fig. 2-4I-N) that fell between the first and second size- frequency peaks. This means that the intermediate size class in Brinkman (2014), interpreted as one year olds, actually represented individuals that were two years old, which is discussed further below. Subadults typically preserved two growth marks that corresponded with the second and third size classes indicating that extensive expansion of the medullary cavity through ontogeny had already obliterated the osteohistological record of the first year of growth, including the first growth mark (Fig. 2-6). This was further evidenced when superimposing the circumference of the yearling growth mark onto sections of specimens from the third size- frequency peak because the yearling circumference placed deep within the medullary cavity region and was therefore completely absent (Fig. 2-6). Subadult growth marks progressively

89 transitioned from localized vascular fluctuations (annuli/zones) early in ontogeny to well-defined

LAGs later in ontogeny, a condition that has also been documented in other hadrosaurids

(Horner et al. 2000; Freedman Fowler and Horner 2015; Woodward et al. 2015; Wosik and

Evans 2015; Wosik et al. 2017a). By four years of age, histological age ranges overlapped by more than 50% with subsequent years, which directly correlated with our fourth size-frequency peak (Fig. 2-8). Although each resident hadrosaurid taxon from the DPF reached comparable adult body lengths of approximately nine meters (Lull and Wright 1942; Ryan and Evans 2005) and could have exhibited a similar growth strategy, this extensive overlap suggests that hadrosaurids from the DPF may have had a higher degree of intra- and/or inter-specific variation in terms of asymptotic body size than previously assumed. However, it is also plausible that the very large isolated tibia (TMP 1979.014.0020) from our sample represents an atypical occurrence of an accelerated growth rate relative to other penecontemporaneous hadrosaurids.

In general, our combined size-frequency distribution of humeri, femora, and tibiae (Fig. 2-2B) revealed multiple relatively distinct size-frequency peaks along a positive parabolic distribution consistent with a long-term, time-averaged depositional origin (Olson 1957). The ontogenetic osteohistological assessment provided a better resolution for age to maturity revealing that the yearling age/size class was heavily underrepresented. Ultimately, Brinkman (2014) was missing at least two years from his initial growth rate estimate of three years to maturity. Our data supplement the work of Brinkman (2014) and indicate that the alternate hypothesis of segregation between adult and juvenile hadrosaurids (Varricchio and Horner 1993) be further explored, which we discuss below (Fig. 2-9).

2.5.1 Comparison with Other Hadrosaurid Taxa

Retrocalculation revealed that the sampled tibiae from Maiasaura and the two DPF specimens were each missing one growth year, whereas Probrachylophosaurus was missing two years.

Estimates of the tibial circumference of the growth mark that would have corresponded with the first year of age ranged from 62–100 mm depending on the specimen/taxon. This aligned with the recorded tibial circumference of 84.5 mm from TMP 1979.014.0308 and indicated that retrocalculation was accurately estimating the missing growth record. Growth modeling estimations indicated that both of the DPF specimens attained 95% asymptotic body mass by seven years of age, whereas Maiasaura and Probrachylophosaurus did so by nine years, based on our reanalysis. The maximum growth rate of TMP 2016.012.0192 was ~26% (~225 kg/yr) larger than Maiasaura and Probrachylophosaurus even though the asymptotic body mass of

TMP 2016.012.0192 was estimated to be ~650 kg and ~1000 kg less than Maiasaura and

Probrachylophosaurus, respectively, based on results from our averaged body mass growth models. This truncation of two years to attain 95% asymptotic body mass suggests that hadrosaurids from the DPF exhibited a slightly faster growth rate relative to hadrosaurids from the neighboring TMF. Although it is intriguing that data from both mature tibiae supported this general strategy amongst hadrosaurids from the DPF, a larger histological sample of long bones from adult individuals of known taxonomic identity is needed to further evaluate this potential difference in growth rate, as well as its consistency across the diverse paleocommunity that flourished during the approximately 1.5 million years (Currie 2005) represented by our sample.

2.5.2 Socioecology, Population Structure, and Seasonal Preservation

Patterns

The shape of the size-frequency distribution recovered in our study reflected a typical attritional assemblage (Olson 1957), with high hatchling mortality followed by a peak period of late juvenile (~2 years old) survivorship that culminated in an accumulation of senescent adults. If this size-frequency distribution is an accurate representation of the mortality rate of hadrosaurids from the DPF, then it appears they followed a Type II survivorship curve (Deevey 1947), similar to extant large-bodied herbivores and that described in a composite sample comprised of at least one catastrophic death assemblage of the penecontemporaneous hadrosaurine Maiasaura peeblesorum (Woodward et al. 2015). There is, however, a notable sampling gap in our DPF dataset—the yearling size class was heavily underrepresented across all sampled bone elements and in the combined size-frequency distribution (Fig. 2-9). Interestingly, these results paralleled those from the paleodemographic study of Maiasaura that also had a notable underrepresentation of size classes under 30 cm for tibia length (Woodward et al. 2015), which corresponds with the hatchling to yearling size range from the DPF (Fig. 2-10).

The absence of the yearling size class in both the DPF and TMF samples is intriguing and has been noted before from slightly different perspectives in other taphonomic bonebed studies. For example, catastrophic mass deaths of Edmontosaurus (Christians 1992; Colson et al. 2004; Bell and Campione 2014; Evans et al. 2015a; Wosik and Evans 2015; Ullmann et al. 2017; Wosik et al. 2017a), Saurolophus (Bell et al. 2018), and Shantungosaurus (Hone et al. 2014), do not contain individuals smaller than what would be expected at two years of age. In a hadrosaurid tracksite from Denali National Park, Alaska, footprints of putatively yearling-sized individuals are excessively rare (n = 4) relative to any other size class (n > 16) including nestlings (Fiorillo

92 et al. 2014). Conversely, monodominant bonebeds consisting only of late juvenile to subadult sized individuals have also been well-documented from North America (Gangloff and Fiorillo

2010; Scherzer and Varricchio 2010; Scott 2015; Mori et al. 2016) and eastern Asia (Lauters et al. 2008) for both hadrosaurine and lambeosaurine hadrosaurids.

One explanation of this pattern is that the underrepresentation of yearlings is an artifact of taphonomic biases (e.g. hydraulic winnowing, predation) against the preservation of small- bodied skeletons in fluvial systems (Brown et al. 2013b; Brown et al. 2013c; Evans et al. 2013;

Mallon and Evans 2014). Given that nestling and two year old individuals are well-preserved in the DPF and TMF, it is difficult to imagine a taphonomic process that would selectively act against the preservation of yearlings, or an intermediate size class between hatchlings and subadults. In addition, our broad dataset provides a comprehensive representation of the current fossil record for over a century of collecting from the DPF and embodies a time-averaged assemblage of ~1.5 million years from a wide range of taphonomic modes (e.g. articulated, associated, disarticulated, isolated), making it improbable that our sample would be missing this specific size class. Second, it may be possible that yearlings experienced very low mortality rates and had abnormally high survivorship, as suggested for Maiasaura (Woodward et al. 2015), which, when combined with high juvenile growth rates, resulted in an underrepresentation of this size class in the DPF sample. However, the concept of survivorship is difficult to address for extinct populations because the initial population has to be assumed (Voorhies 1969), and modern analogues of hadrosaurids such as ungulates (Carrano et al. 1999) may not be comparable because of their differentiating growth strategies and ecologies.

It may be possible that segregation between juveniles and adults occurred as a result of seasonal factors within the DPF paleoenvironment. Mass deaths of ceratopsians from the DPF have been

93 consistently attributed to flood-induced drowning and the taphonomic, geological, and paleoecological data have supported this interpretation (Currie and Dodson 1984; Visser 1986;

Ryan et al. 2001; Eberth and Getty 2005; Eberth et al. 2010). These seasonal monsoonal floods have also been linked to favorable fossil preservation, such that the attritional assemblage in the

DPF may have a considerable seasonal overprint, as suggested by Eberth et al. (2010) and

Brinkman (2014) in their interpretations of the ceratopsid and hadrosaurid components, respectively, of this fossiliferous dinosaur assemblage. However, most researchers have been hesitant to hypothesize a specific scenario for the events that led to such a large scale depositional pattern. Eberth and Getty (2005) suggested that the lowland environment would not have provided significant high ground for large vertebrates such as ceratopsians during severe, seasonal storm induced flooding. They proposed a seasonal preservation pattern related to monsoonal storms for the origin of ceratopsian bonebeds in Dinosaur Provincial Park, which was further supported by data from an integrated climate model and oxygen isotope study (Fricke et al. 2010). In terms of hadrosaurids, these storms may have driven the more susceptible juveniles away from the area, at least temporarily, until they attained a large enough body size around age two or three to withstand these environmental pressures.

Interestingly, Henderson (2014) investigated the resilience of adult ceratopsids and hadrosaurids to drowning during large flood events using a series of three-dimensional models of representatives from both dinosaur groups found in the DPF. He demonstrated that hadrosaurids would have had their heads clear of the high water surface enabling breathing and were therefore more resistant than ceratopsians, which would have had their heads fully immersed due to a more anterior center of gravity being weighed down by extensive cranial ornamentations. Adult hadrosaurids had a general height of 2.5 meters (Mallon et al. 2013) and would have likely been able to stand above most high water surfaces, whereas yearlings with a height of 0.5–1.0 meters

(Mallon et al. 2013), similar to adult ceratopsians from the DPF, would have been completely submerged if the water surface was above 1 meter. If hadrosaurids were capable of floating or swimming to maintain their heads above the water surface, the smaller body mass of yearlings would have been more susceptible to being carried away by the massive flooding. In this scenario, we would expect hadrosaurids of the yearling size class to preserve in large numbers, but our data provides contrary evidence suggesting that the segregation between yearlings and adults may have been a real biological signal.

Additional evidence that resident hadrosaurids from the DPF (those that had reached 2 years old and about 50% adult body length) did not perish during the monsoonal storms can be drawn from our osteohistological data using patterns in the bone microstructure. Many animals undergo a significant increase in their growth rate at the start of the warm or wet season (i.e. spring and summer) (Köhler et al. 2012 and references therein), which can be directly observed in the osteohistological record via an increase in bone vascularity and deposition. This increase is best observed in juvenile and subadult individuals that have not yet reached skeletal maturity

(Huttenlocker et al. 2013). Conversely, change in vascular patterns from reticular to laminar is characteristic of slower growth in hadrosaurids (Horner et al. 2000; Huttenlocker et al. 2013;

Woodward et al. 2015). Under this scenario, if death occurred during the warm/wet season, the histological record of skeletally immature individuals should reflect rapid growth closer towards the periosteal surface. However, our entire osteohistological sample of hadrosaurid dinosaurs from the DPF (n = 35), with the exclusion of nestlings which were undergoing very rapid growth, consistently exhibited some degree of laminar (circumferential) orientation of vasculature at the periosteal surface. Although our osteohistological sample size must be increased before robust conclusions can be made, the current data tentatively indicate that the sampled hadrosaurids would have perished closer to the cold/dry season when growth naturally

95 slows down due to variable resource availability (e.g. Köhler 2012), rather than during a period of monsoonal flooding. Therefore, the hadrosaurids that reside in the DPF systems do not seem to be particularly vulnerable to the monsoonal flooding, supporting Henderson (2014).

This brings into question the paleoecological residence of yearling groups of hadrosaurids within the DPF biocenose. Our data suggest that hadrosaurid yearlings were not present here between hatching and about 2 years of age (~50% adult body length), at least during times of high preservation potential (e.g., monsoon season with associated flooding). These proposed major flooding events are consistent with isotopic evidence indicating spring/summer movements of moisture-laden air masses from the Western Interior Seaway, as well as climatological simulations of a strong monsoon (Fricke et al. 2010). Residence in more upland paleoenvironments may have been a possibility for at least a portion of the year, particularly during the flooding season. This may be supported by the large number of juvenile dominated bonebeds and nesting sites found in more inland depositional settings in the Belly River and

Judith River groups (e.g. Horner and Makela 1979; Varricchio and Horner 1993; Horner 1994,

1999; Horner and Currie 1994; Scherzer and Varricchio 2010), although the presence of hatchlings at Dinosaur Provincial Park demonstrates that some taxa nested in lowland areas

(Tanke and Brett-Surman 2001). Yearling-sized juveniles had approximate total body lengths of

2.5 meters, which was about a quarter of the size of the average adult from the DPF (~9 m). This is similar in size with other penecontemporaneous small- to mid-sized ornithischian dinosaurs such as hypsilophodontids and pachycephalosaurids (Ryan and Evans 2005) that based on analyses of vertebrate microfossil assemblages, preferentially lived in terrestrial inland paleoenvironments (Brinkman 1990; Baszio 1997; Brinkman et al. 1998), although a taphonomic study of pachycephalosaurs suggested alluvial and coastal plain settings were similarly common

(Mallon and Evans 2014).

Two general hypotheses have been proposed to explain intraspecific spatial segregation patterns in animals (e.g. Ruckstuhl 2007; Main 2008). The social segregation hypothesis focuses on intraspecific interactions. For example, size-based competition for resources has been well- documented in a wide variety of extant taxa (Fayet et al. 2015 and references therein) and proposed for herbivorous dinosaurs from the DPF in terms of feeding height stratification

(Mallon et al. 2013). Bramble et al. (2017) reported that hadrosaurids had very dynamic dentition, including anterior-posterior migration of tooth families within the dental batteries through ontogeny. The pattern of that migration, which was hypothesized to be caused by complex forces associated with food processing, changed with age, which might reflect, in part, ontogenetic switches in diet. Intriguingly, Chin et al. (2017) analyzed presumably fossilized fecal matter, which was referred to hadrosaurids, and revealed a diet based on decaying logs and crustaceans, indicating that these dinosaurs may have had a more flexible, seasonally-based diet than currently believed. Therefore, the data support, albeit at a very preliminary stage, the idea that ecological niche partitioning based on age might have been occurring in hadrosaurids.

Assortment based on phenotypic similarity as reflected in body size, sex, relatedness, and various physiological characters affecting metabolism and locomotory performance has been noted for a variety of extant gregarious species (e.g. Geist 1968; Schaffer and Reed 1972; Estes 1974; Geist

1974; Jarman 1974; Wiley 1974; Triesman 1975; Western 1975; Emlen and Oring 1977; Fitch and Henderson 1977; Geist 1977; Molnar 1977; Jarman 1983; Demment and van Soest 1985;

Godsell 1991). The benefits of grouping with similar conspecifics include, for example, enhanced anti-predator behaviour through dilution effects, enhanced vigilance, and increased foraging efficiency (Killen et al. 2017 and references therein). It is possible that hadrosaurids from the DPF may have had a more complex population structure than previously assumed.

Based on numerous occurrences of low-diversity bonebeds, several hadrosaurid species are

97 thought to have formed large-scale gregarious associations for at least a portion of the year

(Horner et al. 2004) paralleling the ecomorphology of modern ungulates (Carrano et al. 1999).

Within that gregarious social framework, could yearlings have formed groups separate from the rest of the population? Forster (1990) noted two occurrences of homogenously sized groups of individuals from the Cloverly Formation of Montana belonging to the ornithopod Tenontosaurus.

Individuals in these groups were 50–65% the size of adults (Forster 1990), falling well within the expected values for late juveniles in this taxon. Varricchio and Horner (1993) reported a consistent lack of association between small (total body length < 3 m) and large sized individuals in six hadrosaurid assemblages from the TMF. If not due to rapid growth rates, they suggested that juveniles spent a part of their developmental period associating with similarly sized individuals (Varricchio and Horner 1993; Varricchio 2011). Finally, although they did not discuss possible causes, Fiorillo and Gangloff (2001) reported that, of the several thousand specimens recovered from the Liscomb Bonebed from the North Slope of Alaska, the vast majority were referred to Edmontosaurus sp. and matched the size profile of the yearling size class from the DPF.

The second explanation for intraspecific spatial segregation is based on habitat selection. In this scenario sex- or age-related differences in predation pressure and/or nutritional requirements drive changes in habitat selection. Although there is very little research on age-related habitat segregation, some studies suggest that juveniles might inhabit environments that are more dangerous and/or prone to fluctuation than conspecific adults, based primarily on foraging needs.

For example, Ficetola et al. (2013) reported that juvenile cave salamanders, Hydromantes strinatii, resided near the cave entrance, while adults preferred the deeper interiors. The entrance habitat represented a trade-off between increased foraging efficiency (higher concentration of invertebrates), suboptimal environmental variables (warmer, higher humidity), and increased

98 predation pressure; increased foraging requirements of juveniles was thought to offset the dangers of inhabiting such a risky environment. Based on our discussion to this point, we propose habitat selection might also be based on age-related differences in susceptibility to seasonal changes in the environment. In the case of hadrosaurids in the DPF, the small body size of juveniles rendered them more susceptible to drowning in large scale coastal flooding events, potentially forcing them to move more inland until they were large enough (~50% adult body size) to withstand the environmental challenge. The benefit to yearlings of moving inland is obvious. However, the question that needs to be addressed to examine our suggestion further is what, if any, were the costs of such a change in habitat preference particularly in terms of food quality and predation pressure?

Taken together, both social and habitat-based factors could have driven juveniles inland and resulted in the formation of juvenile-only groups (Forster 1990; Lauters et al. 2008; Gangloff and

Fiorillo 2010; Scherzer and Varricchio 2010; Scott 2015; Mori et al. 2016) until they were about two years of age (~50% adult body size), and thus capable of joining the main herd, or population, on a more permanent basis. Curiously, this is within the size and age ranges that correspond with the inflection point of the growth curves, which marks the transition from growth acceleration to deceleration and has been of physiological importance because it generally coincides with the onset of reproductive maturity in ecologically equivalent extant vertebrates (e.g. ungulates) (e.g. Brody 1964; Reiss 1989; Cooper et al. 2008; Lee and Werning

2008). Therefore, we postulate that the reintegration of juveniles into the population could have also coincided with the onset of sexual maturity. Further studies are needed to evaluate ecological modes of segregation and niche partitioning, ontogenetic feeding strategies, and the potentially differential distribution of cohorts between environments (e.g. inland vs. coastal).

2.6 Conclusion

The newly constructed size-frequency distribution of the DPF hadrosaurid assemblage revealed four relatively distinct size-frequency peaks, which formed a positive parabolic distribution consistent with patterns exhibited by attritional assemblages. When integrated with the osteohistological growth mark data, the size-frequency peaks progressively aligned with age and revealed that the yearling size class was heavily underrepresented in the size-frequency distribution. If not due to preservation, this may suggest hadrosaurids from the DPF had high survivorship until two years of age if they managed to survive the initial nestling mortality rate or that juveniles were segregated from the main herd and not present in the DPF region during this ontogenetic interval. An osteohistological growth curve analysis revealed asymptotic body size of hadrosaurids from the DPF was attained in approximately seven years, which was faster by two years than taxa from Montana. The data suggested size-frequency distributions of attritional samples underestimate age and overestimate growth rate and should be paired with osteohistology to provide more accurate and precise interpretations, with size-frequency distributions providing important insights on population paleoecology and osteohistology supplying data specific to individuals.

2.7 Acknowledgments

Access to specimens was facilitated by C. Mehling and M. Norrell (AMNH), M. Currie, J.

Mallon, and K. Shepard (CMN), B. Iwama and K. Seymour (ROM), R. Bavington, D. Brinkman,

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T. Courtney, G. Housego, and B. Strilisky (TMP), and M. Burns (UALVP). Collections research for this project was generously funded by the Dinosaur Research Institute Student Project Grant

(to MW). Fieldwork was funded by the Royal Tyrrell Museum Cooperating Society Student

Research Program (to MW) and assisted by C. Brown, D. Tanke, and TMP staff and volunteers.

Discussions with C. Brown, T. Cullen, D. Eberth, D. McLennan, R. Reisz, M. Ryan, M. Silcox,

D. Tanke, C. Woodruff, and H. Woodward greatly enhanced the manuscript.

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2.8 Tables

Table 2-1. Summary of parameter values and results for averaged age retrocalculation growth models along with estimated values for the age of first record growth mark (Est GM 1 Age) and estimated values for the minimum diaphyseal circumference of the estimated first growth mark

(Est GM 1 Circ). Abbreviations: m = slope; A = asymptote; K = constant; I = inflection point.

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Taxon Specimen # Model m A K I Est GM 1 Age Est GM 1 Circ Retrocalculation 0.71 318.44 0.66 0.85 1.65 80.75 MOR 758 NC-7-4- Maiasaura - 96-16 'T46' Retrocalculation - GM1 1.88 354.39 0.29 7.09 10.74 Body Mass 0.25 3989.62 0.25 1.40 - - Retrocalculation 3.54 346.63 0.60 8.93 10.21 - Hypacrosaurus MOR 549 Retrocalculation - GM1 5.55 345.40 0.71 13.56 15.75 - Body Mass 2.05 3984.04 0.62 11.32 - - Retrocalculation 0.66 363.27 0.47 1.25 2.64 61.38 Probrachylophosaurus MOR 2919 Retrocalculation - GM1 0.62 362.01 0.51 1.14 3.25 - Body Mass 0.40 4341.11 0.38 2.71 - - Retrocalculation 1.01 395.69 0.71 1.46 2.00 100.17 TMP DPF indet. - 1979.014.0020 Retrocalculation - GM1 0.40 395.30 0.72 0.49 2.06 Body Mass 0.80 5337.76 0.66 2.79 - - Retrocalculation 1.05 328.48 0.76 1.33 1.63 64.17 TMP DPF indet. - BB 50 327.69 0.83 0.51 1.71 - 2016.012.0192 Retrocalculation - GM1 0.50 Body Mass 0.66 3344.04 0.64 2.36 - -

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Table 2-2. Summary of retrocalculated ages, growth mark circumferences, estimated body masses using the averaged models, and the estimated growth rate between years of the five hadrosaurid tibiae analyzed in this study. GM = growth mark, negative (-) values denote missing growth marks based on age retrocalculation; Circ = growth mark circumference; BM = estimated body mass (kg).

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Maiasaura Probrachylophosaurus TMP 1979.014.0020 TMP 2016.012.0192 GM Age Circ BM kg/yr GM Age Circ BM kg/yr GM Age Circ BM kg/yr GM Age Circ BM kg/yr -1 0.65 81 50 -2 0.64 61.5 21 -1 1 100 87 -1 0.63 64 25 375 208 627 301 1 1.65 165 426 -1 1.64 136.5 229 1 2 202 713 1 1.63 151 326 884 582 1227 723 2 2.65 240 1310 1 2.64 208 811 2 3 282 1940 2 2.63 223 1049 434 719 1415 1095 3 3.65 264 1743 2 3.64 257 1529 3 4 338.5 3355 3 3.63 283 2143 270 855 991 527 4 4.65 277 2014 3 4.64 298 2384 4 5 369 4346 4 4.63 304.5 2670 394 638 344 272 5 5.65 294 2408 4 5.64 322.5 3022 5 6 378.5 4691 5 5.63 314.5 2942 307 535 284 85 6 6.65 306 2715 5 6.64 340.5 3557 6 7 386 4975 6 6.63 317.5 3027 390 79 78 72 7 7.65 320 3104 6 7.64 343 3635 7 8 388 5053 7 7.63 320 3099 363 96 79 44 OC - 332 3467 7 8.64 346 3732 8 9 390 5131 8 8.63 321.5 3143 Hypacrosaurus 148 59 44 GM Age Circ BM kg/yr 8 9.64 350.5 3879 9 10 391.5 5191 9 9.63 323 3187 1 10.21 236 1227 100 60 60 590 9 10.64 353.5 3980 10 11 393 5251 10 10.63 325 3246 2 11.21 269 1817 119 60 38 580 10 11.64 357 4099 11 12 394.5 5311 11 11.63 326.3 3284 3 12.21 295 2397 157 61 38 439 11 12.64 361.5 4256 12 13 396 5372 12 12.63 327.5 3322 4 13.21 312 2836 107 41 61 550 12 13.64 364.5 4363 13 14 397 5413 13 13.63 329.5 3383 5 14.21 331 3386 36 31 31 156 13 14.64 365.5 4399 14 15 397.8 5444 14 14.63 330.5 3414 6 15.21 336 3542 36 21 31 160 OC - 366.5 4435 15 16 398.3 5464 15 15.63 331.5 3445 7 16.21 341 3702 31 16 33 OC - 399 5495 16 16.63 332 3461 OC - 342 3735 16 17 17.63 332.5 3476 16 OC - 333 3492

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2.9 Figures and Figure Captions

Figure 2-1. Geographic map distinguishing hadrosaurid taxa between the Dinosaur Park

Formation (DPF) of Alberta, Canada, and the Two Medicine Formation (TMF) of Montana,

USA.

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106 107

Figure 2-2. Combined size-frequency distributions of hadrosaurids from the Dinosaur Park

Formation (DPF) of Alberta, Canada. Tick marks below each size-frequency distribution correspond with individual bones. A, Original size-frequency distribution from Brinkman (2014) scaled to ROM 845 (Corythosaurus casuarius). N = 58 femora and tibiae. B, Updated size- frequency distribution from our study scaled to ROM 845. N = 204 isolated humeri, femora, and tibiae. Dark shade represents raw measurement values; light shade represents estimated values based on an Ordinary Least Squares (OLS) regression between total length and minimum diaphyseal circumference (Supplementary Table S2-3, Supplementary Figure S2-1C, D).

Ontogenetic progression of Corythosaurus was included for visual reference of well-known associated skeletons. Skull progression was used to represent approximate size classes and does not directly correspond with the listed specimen (modified from Evans 2010).

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Figure 2-3. Size-frequency distributions of hadrosaurid humeri (A, B), femora (C, D), and tibiae

(E, F) from the Dinosaur Park Formation (DPF) of Alberta, Canada. A, C, E, Total length. B, D,

F, Minimum diaphyseal circumference. Tick marks below each size-frequency distribution correspond with individual bones. Dark shade represents raw measurement values; light shade represents estimated values based on an Ordinary Least Squares (OLS) regression between total length and minimum diaphyseal circumference (Supplementary Table S2-3, Supplementary

Figure S2-1C, D).

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Figure 2-4. Osteohistology of nestling through subadult hadrosaurid tibiae from the Dinosaur

Park Formation (DPF) of Alberta, Canada under plain-polarized (PP) and cross-polarized (XP) light microscopy. A, B, E, G, Nestling (TMP 1997.012.0216). C, D, F, H, Early juvenile (TMP

1991.036.0783). I-N, Late juvenile (TMP 1979.014.0308). O-R, Subadult (TMP 1994.012.0870).

A, B, C, D, I, K, O, P, Full transverse cross-sections. E-H, M, N, Q, R, Close-up of dotted boxed region with arrows indicating visible growth marks and general bone vasculature orientation. J,

L, Close-up of solid boxed region from I and K, respectively, showing the yearling growth mark.

Abbreviations: L, laminar; MC, medullary cavity; P, plexiform; R, reticular.

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Figure 2-5. Osteohistology of adult hadrosaurid tibiae from the Dinosaur Park Formation (DPF) of Alberta, Canada. A-C, TMP 1979.014.0020. D-F, TMP 2016.012.0192. A, D, Full transverse cross-sections in plain-polarized light. B, E, Traced growth marks with extent of medullary cavity and/or secondary osteon development outlined in dotted central region. C, F, Close-up of boxed region from A, D with arrows indicating visible growth marks and general bone vasculature orientation in plain-polarized light. Abbreviations: L, laminar; MC, medullary cavity; P, plexiform; R, reticular.

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Figure 2-6. Summary of section stacking of tibiae. Schematics highlight cortical bone (solid grey), extent of medullary cavity and/or secondary osteon development (dotted white), and growth marks (solid black line). Circumferences refer to extent of medullary cavity and/or secondary osteon development (MC/SR), growth mark (GM), and outer/periosteal circumference

(Outer).

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Figure 2-7. Hadrosaurid growth curves. A, Tibial minimum diaphyseal circumference growth of individuals with longest growth records from each taxon. B, Body mass growth of currently known hadrosaurid growth records. Growth mark data for other hadrosaurid taxa was taken from the literature and reanalyzed (summarized in Table 2-2): Hypacrosaurus (Cooper et al. 2008),

Maiasaura (Woodward et al. 2015), and Probrachylophosaurus (Freedman Fowler and Horner

2015).

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119

Figure 2-8. Size-frequency distribution of tibial minimum diaphyseal circumference integrated with osteohistology. Estimated values were based on Ordinary Least Squares regressions

(Supplementary Table S2-3, Supplementary Figure S2-1C, D).

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Figure 2-9. Comparative summary of size-frequency distributions across all individual bone elements. Note the general lack of or heavy under representation of individuals between 20-40% of ROM 845, a presumably mature adult. Data for the total length ‘Brinkman’ distribution is from Brinkman (2014).

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Figure 2-10. Density comparison of long bone and tracksite size distributions of hadrosaurid bonebeds. N refers to sample size. Data derived from personal measurements or published literature: 1Wosik et al. 2017a; 2Evans et al. 2015a; 3Fiorillo et al. 2014; 4Woodward et al. 2015;

5Bell et al. 2018; 6Hone et al. 2014; 7Varricchio & Horner 1993; 8Scherzer & Varricchio 2010;

9Lauters et al. 2008.

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1 2.10 Supplementary Tables

9 Supplementary Table S2-1. Summary of total length and minimum diaphyseal circumference

10 data of associated skeletons from the DPF used in SMA analyses. DPCW refers to the

11 deltopectoral crest width of the humerus.

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Humerus Radius Ulna Femur Tibia Fibula Humerus+Femur Specimen Taxon Length Circ DPCW Length Length Length Circ Length Circ Length Combined Circ

AMNH 5240 C. casuarius 1080 1000 950

AMNH 5338 C. casuarius 546 577 609 987 924 882

AMNH 5340 Lambeosaurus 305 320 350 590 550 530

AMNH 5350 G. notabilis 518 207 132 1150 440 1005 354 945 647

CMN 2278 G. notabilis 260 1125 1030 980

CMN 34825 C. sp 160 736 283 702.5 234 632.5 443

CMN 8676 C. excavatus 455 185 99 513 562 890 813 775

CMN 8703 L. clavinitialis 540 140 628 658 1020 390 1018.5 940

CMN 8784 G. notabilis 111 515

MCSNM 345 G. notabilis 730 780 785 1150 1080

ROM 1218 L. lambei 533.5 225 134.5 622 691 1063 380.5 957.5 329 911.5 605.5

ROM 764 G. notabilis 608.5 242 123.5 576 624 1026 920 296 883.5

ROM 768 Para. walkeri 562 259.5 165 505.5 557.5 1065 410 669.5

ROM 787 Pro. maximus 536 218 132 485 545 1000 345 881 313 839 563

ROM 845 C. casuarius 556 246.5 147.5 656.5 712.5 1075.5 384.5 998 345.5 951 631

TMP 1966.004.0001 L. magnicristatus 505 140 630 1060 1015 970

TMP 1980.022.0001 G. notabilis 552.5 502 520 955 860 815

TMP 1980.023.0004 C. casuarius 546 616 671 1145 996

TMP 1980.040.0001 C. casuarius 580 235 622 645 1070 950 905

127

TMP 1982.037.0001 C. casuarius 892 314 867.5 775

TMP 1982.038.0001 L. lambei 665 685 1140 404.5 1072.5 361 995

TMP 1984.001.0001 P. maximus 560 540 584 1045 895 900

TMP 1984.121.0001 C. casuarius 530 640 650 1040 980

TMP 1998.058.0001 lambeosaurine sp. 260 307 303 528 460 447

UALVP 13 C. excavatus 238 1144.5 385 992.5 342 996 623

128

12 Supplementary Table S2-2. Results from SMA regression analyses using associated skeletons

13 from the DPF. Femur length = x.

129

Slope Comparison (y) N R2 (m) 95% CI m Intercept (b) 95% CI b p-value Trend

1. Humerus Length 18 0.88 1.11 0.93 1.34 -1.43 -2.95 -0.15 8.20E-09 iso

2. Humerus Circ 12 0.90 1.05 0.84 1.31 -1.88 -3.66 -0.44 2.56E-06 iso

3. Radius Length 18 0.86 1.12 0.92 1.36 -1.39 -3.04 -0.03 2.47E-08 iso

4. Ulna Length 17 0.91 1.12 0.95 1.32 -1.34 -2.70 -0.18 2.67E-09 iso

5. Femur Circ 10 0.87 0.96 0.72 1.29 -0.75 -3.00 0.93 8.37E-05 iso

6. Tibia Length 23 0.96 1.01 0.92 1.10 -0.15 -0.76 0.44 2.23E-16 iso

7. Tibia Circ 8 0.94 0.97 0.76 1.23 -0.94 -2.77 0.50 6.74E-05 iso

8. Fibula Length 20 0.98 1.01 0.94 1.08 -0.19 -0.66 0.24 2.23E-17 iso

130

14 Supplementary Table S2-3. Results from OLS regression analyses using complete isolated

15 elements.

131

Slope Limb Element (x) N R2 (m) 95% CI m Intercept (b) 95% CI b p-value Trend

TL 39 0.98 1.01 0.96 1.05 -0.92 -1.17 -0.66 2.30E-34 iso Humerus C 39 0.98 0.98 0.93 1.02 0.99 0.78 1.02 2.30E-34 iso

TL 22 0.86 0.81 0.66 0.97 -0.26 -1.21 0.68 5.41E-10 neg Radius C 22 0.86 1.06 0.86 1.26 1.14 0.19 2.09 5.41E-10 iso

TL 24 0.97 0.98 0.90 1.06 -1.25 -1.72 -0.78 3.76E-18 iso Ulna C 24 0.97 0.99 0.91 1.07 1.42 1.05 1.79 3.76E-18 iso

TL 40 0.99 0.98 0.95 1.01 -0.85 -1.04 -0.66 1.89E-39 iso Femur C 40 0.99 1.01 0.98 1.04 0.91 0.75 1.07 1.89E-39 iso

TL 40 0.99 1.07 1.04 1.10 -1.51 -1.69 -1.33 1.70E-42 pos Tibia C 40 0.99 0.93 0.91 0.96 1.45 1.32 1.58 2.08E-42 neg

TL 22 0.94 0.93 0.82 1.05 -1.34 -2.09 -0.59 1.88E-13 iso Fibula C 22 0.94 1.00 0.88 1.13 1.77 1.17 2.36 1.88E-13 iso

HumC+FemC TibC 6 0.99 0.91 0.82 1.01 1.12 0.57 1.66 1.12E-05 iso

132

16 Supplementary Table S2-4. Parameter values for each age retrocalculation growth model along

17 with AICc scores, estimated values for age of first record growth mark (Est GM 1 Age), and

18 estimated values for minimum diaphyseal circumference of the estimated first growth mark (Est

19 GM 1 Circ).

133

AIC Specimen # Taxon Model AIC AICc dAICc weight m A K I Est GM 1 Age Est GM 1 Circ

MOR 758 NC-7-4-96-16 'T46' Maiasaura Monomolecular 52.92 55.92 0.00 0.44 0 320.83 0.55 -0.15 1.16 49.83

von Bertalanffy 54.13 57.13 1.20 0.24 2/3 318.14 0.65 0.83 1.64 77.20

Gompertz 54.68 57.68 1.75 0.19 0.999 317.00 0.70 1.33 1.94 85.20

Logistic 56.14 59.14 3.22 0.09 2 314.18 0.86 2.83 2.96 52.01

Extreme 58.35 61.35 5.43 0.03 4 310.32 1.23 5.25 4.76 34.20

Innominate 61.04 64.04 8.11 0.01 8.4 305.33 2.24 7.38 6.30 27.37

Averaged 54.77 57.77 - 1.00 0.71 318.44 0.66 0.85 1.65 80.75

MOR 549 Hypacrosaurus Monomolecular 37.35 40.35 6.17 0.03 0 353.90 0.35 -0.21 2.92 115.60

von Bertalanffy 35.90 38.90 4.73 0.05 2/3 351.82 0.40 1.42 3.90 72.25

Gompertz 35.20 38.20 4.02 0.07 0.999 350.92 0.42 2.31 4.51 41.76

Logistic 33.26 36.26 2.09 0.20 2 348.63 0.49 5.24 6.74 34.79

Extreme 31.17 34.17 0.00 0.55 4 345.44 0.64 10.67 11.20 26.09

Innominate 34.64 37.64 3.46 0.10 8.4 341.46 0.97 17.80 17.13 25.45

Averaged 30.99 33.99 - 1.00 3.54 346.63 0.60 8.93 10.21 30.16

MOR 2919 Probrachylophosaurus Monomolecular 74.75 75.95 0.00 0.34 0 364.56 0.41 -0.17 1.89 128.69

von Bertalanffy 74.88 76.08 0.13 0.32 2/3 363.15 0.47 1.22 2.66 66.14

Gompertz 75.31 76.51 0.56 0.25 0.999 362.54 0.50 1.97 3.14 30.04

Logistic 77.50 78.70 2.76 0.09 2 361.05 0.60 4.35 4.49 40.16

Extreme 82.72 83.92 7.97 0.01 4 359.11 0.81 8.54 8.17 26.15

134

Innominate 89.92 91.12 15.17 0.00 8.4 357.20 1.31 13.53 12.13 25.60

Averaged 75.09 76.29 - 1.00 0.66 363.27 0.47 1.25 2.64 61.38

TMP 1979.014.0020 DPF Monomolecular 79.96 80.96 6.19 0.02 0 397.07 0.57 -0.11 1.13 52.44

von Bertalanffy 74.91 75.91 1.14 0.30 2/3 396.09 0.66 0.90 1.66 90.47

Gompertz 73.78 74.78 0.00 0.54 0.999 395.67 0.71 1.44 2.00 101.16

Logistic 76.52 77.52 2.74 0.14 2 394.61 0.86 3.12 3.18 62.22

Extreme 89.23 90.23 15.45 0.00 4 393.17 1.22 5.58 5.27 27.95

Innominate 102.79 103.79 29.01 0.00 8.4 391.72 2.12 8.66 7.36 27.69

Averaged 73.80 74.80 - 1.00 1.01 395.69 0.71 1.46 2.00 100.17

TMP 2016.012.0192 DPF - BB 50 Monomolecular 100.44 101.30 2.88 0.09 0 329.71 0.58 -0.14 0.91 150.85

von Bertalanffy 98.04 98.90 0.48 0.30 2/3 328.85 0.69 0.80 1.34 53.23

Gompertz 97.56 98.42 0.00 0.38 0.999 328.48 0.74 1.27 1.61 63.83

Logistic 98.68 99.53 1.12 0.22 2 327.56 0.93 2.67 2.51 38.38

Extreme 105.65 106.50 8.09 0.01 4 326.34 1.38 4.80 4.01 39.78

Innominate 115.77 116.63 18.21 0.00 8.4 325.11 2.53 6.71 5.32 27.91

Averaged 97.56 98.41 - 1.00 1.05 328.48 0.76 1.33 1.63 64.17

135

20 Supplementary Table S2-5. Parameter values for each age retrocalculation growth model after

21 the first (earliest/smallest) recorded growth mark was artificially removed from each specimen’s

22 dataset.

136

AIC Specimen # Taxon Model AIC AICc dAICc weight m A K I Est GM 1 Age

MOR 758 NC-7-4-96-16 'T46' Maiasaura Monomolecular 28.98 32.98 0.00 1.00 0.21 0 365.20 0.19 -0.37 5.17

von Bertalanffy 29.07 33.07 0.09 0.96 0.20 2/3 359.26 0.23 2.49 6.76

Gompertz 29.12 33.12 0.14 0.93 0.20 0.999 356.80 0.25 3.98 7.73

Logistic 29.32 33.32 0.33 0.85 0.18 2 350.84 0.30 8.60 11.18

Extreme 29.81 33.81 0.83 0.66 0.14 4 343.03 0.41 16.66 17.76

Innominate 31.01 35.01 2.02 0.36 0.08 8.4 334.57 0.64 26.76 26.22

Averaged 30.20 34.20 - - 1.00 1.88 354.39 0.29 7.09 10.74

MOR 549 Hypacrosaurus Monomolecular 31.14 35.14 4.97 0.08 0.04 0 350.17 0.41 -0.18 3.38

von Bertalanffy 30.59 34.59 4.41 0.11 0.06 2/3 349.26 0.44 1.27 4.39

Gompertz 30.32 34.32 4.14 0.13 0.07 0.999 348.84 0.46 2.10 5.03

Logistic 29.51 33.51 3.34 0.19 0.10 2 347.72 0.51 5.00 7.40

Extreme 28.06 32.06 1.88 0.39 0.21 4 345.95 0.62 10.99 12.56

Innominate 26.18 30.18 0.00 1.00 0.53 8.4 343.48 0.86 20.11 20.54

Averaged 26.90 30.90 - - 1.00 5.55 345.40 0.71 13.56 15.75

MOR 2919 Probrachylophosaurus Monomolecular 69.37 70.70 0.00 1.00 0.46 0 362.46 0.47 -0.15 2.46

von Bertalanffy 70.56 71.90 1.20 0.55 0.25 2/3 361.93 0.51 1.11 3.31

Gompertz 71.14 72.47 1.78 0.41 0.19 0.999 361.69 0.53 1.84 3.85

Logistic 72.79 74.12 3.43 0.18 0.08 2 361.06 0.60 4.35 5.88

Extreme 75.62 76.95 6.25 0.04 0.02 4 360.08 0.73 9.46 10.22

137

Innominate 79.84 81.18 10.48 0.01 0.00 8.4 358.80 1.05 16.93 16.64

Averaged 70.48 71.82 - - 1.00 0.62 362.01 0.51 1.14 3.25

TMP 1979.014.0020 DPF Monomolecular 66.75 67.84 0.00 1.00 0.57 0 395.45 0.68 -0.10 1.73

von Bertalanffy 68.54 69.63 1.79 0.41 0.23 2/3 395.20 0.73 0.80 2.36

Gompertz 69.44 70.53 2.68 0.26 0.15 0.999 395.08 0.76 1.33 2.76

Logistic 72.06 73.15 5.30 0.07 0.04 2 394.76 0.84 3.19 4.28

Extreme 76.70 77.79 9.95 0.01 0.00 4 394.22 1.03 6.99 7.53

Innominate 83.96 85.05 17.21 0.00 0.00 8.4 393.39 1.50 12.30 12.07

Averaged 68.19 69.28 - - 1.00 0.40 395.30 0.72 0.49 2.06

TMP 2016.012.0192 DPF - BB 50 Monomolecular 90.30 91.23 0.00 1.00 0.52 0 327.83 0.78 -0.10 1.37

von Bertalanffy 91.84 92.76 1.53 0.46 0.24 2/3 327.64 0.84 0.65 1.87

Gompertz 92.56 93.48 2.25 0.32 0.17 0.999 327.55 0.87 1.08 2.18

Logistic 94.58 95.50 4.27 0.12 0.06 2 327.30 0.98 2.54 3.32

Extreme 97.98 98.91 7.68 0.02 0.01 4 326.87 1.22 5.42 5.71

Innominate 103.32 104.24 13.01 0.00 0.00 8.4 326.15 1.87 9.09 8.71

Averaged 91.62 92.55 - - 1.00 0.50 327.69 0.83 0.51 1.71

138

23 Supplementary Table S2-6. Parameter values for each body mass growth model along with

24 AICc scores.

139

AIC Specimen # Taxon Model AIC AICc dAICc weight m A K I

MOR 758 NC-7-4-96-16 'T46' Maiasaura Monomolecular 91.51 111.51 0.00 1.00 0.76 0 4153.61 0.19 0.96

von Bertalanffy 94.95 114.95 3.43 0.18 0.14 2/3 3552.84 0.35 2.52

Gompertz 96.19 116.19 4.68 0.10 0.07 0.999 3418.11 0.42 2.92

Logistic 98.77 118.77 7.25 0.03 0.02 2 3208.54 0.64 3.66

Extreme 101.31 121.31 9.80 0.01 0.01 4 3061.24 1.07 4.42

Innominate 103.26 123.26 11.74 0.00 0.00 8.4 2981.54 2.07 5.14

Averaged 92.95 112.95 - - 1.00 0.25 3989.62 0.25 1.40

MOR 549 Hypacrosaurus Monomolecular 87.18 107.18 6.15 0.05 0.02 0 4761.57 0.21 8.87

von Bertalanffy 84.51 104.51 3.48 0.18 0.09 2/3 4288.13 0.34 10.32

Gompertz 83.29 103.29 2.26 0.32 0.17 0.999 4154.59 0.41 10.73

Logistic 81.03 101.03 0.00 1.00 0.53 2 3921.74 0.61 11.48

Extreme 83.33 103.33 2.30 0.32 0.17 4 3741.64 1.02 12.23

Innominate 89.25 109.25 8.22 0.02 0.01 8.4 3638.59 1.95 12.94

Averaged 81.00 101.00 - - 1.00 2.05 3984.04 0.62 11.32

MOR 2919 Probrachylophosaurus Monomolecular 166.14 171.14 0.00 1.00 0.49 0 4411.71 0.31 2.04

von Bertalanffy 166.72 171.72 0.58 0.75 0.37 2/3 4284.58 0.43 3.21

Gompertz 168.64 173.64 2.50 0.29 0.14 0.999 4244.74 0.49 3.60

Logistic 174.86 179.86 8.71 0.01 0.01 2 4168.63 0.69 4.38

Extreme 182.07 187.07 15.93 0.00 0.00 4 4095.01 1.16 5.16

140

Innominate 186.92 191.92 20.78 0.00 0.00 8.4 4042.37 2.44 5.75

Averaged 168.76 170.76 - - 1.00 0.40 4341.11 0.38 2.71

TMP 1979.014.0020 DPF Monomolecular 196.00 200.00 11.32 0.00 0.00 0 5424.86 0.44 1.75

von Bertalanffy 184.69 188.69 0.00 1.00 0.59 2/3 5347.76 0.62 2.67

Gompertz 185.43 189.43 0.74 0.69 0.41 0.999 5323.10 0.72 2.97

Logistic 196.49 200.49 11.80 0.00 0.00 2 5276.82 1.03 3.56

Extreme 208.48 212.48 23.80 0.00 0.00 4 5233.76 1.74 4.12

Innominate 215.46 219.46 30.77 0.00 0.00 8.4 5208.13 3.56 4.58

Averaged 184.46 188.46 - - 1.00 0.80 5337.76 0.66 2.79

TMP 2016.012.0192 DPF - BB 50 Monomolecular 214.48 217.81 2.99 0.22 0.14 0 3392.77 0.43 1.46

von Bertalanffy 211.48 214.82 0.00 1.00 0.62 2/3 3340.92 0.64 2.42

Gompertz 213.39 216.73 1.91 0.39 0.24 0.999 3325.03 0.75 2.71

Logistic 220.76 224.09 9.28 0.01 0.01 2 3295.85 1.10 3.26

Extreme 229.01 232.35 17.53 0.00 0.00 4 3270.56 1.93 3.79

Innominate 234.35 237.68 22.86 0.00 0.00 8.4 3260.76 3.89 4.23

Averaged 211.47 214.80 - - 1.00 0.66 3344.04 0.64 2.36

141

2.11 Supplementary Figures

Supplementary Figure S2-1. Bivariate allometric results. A, SMA regressions of forelimb and hindlimb long bone measurements against femur length. N = 25 associated hadrosaurid skeletons from the DPF. B, Overall results of SMA regression analyses, symbol corresponds with slope

(m) and vertical bars correspond with the upper and lower bounds of 95% confidence intervals

(CI) of the slope (m). C, OLS regressions of minimum diaphyseal circumference against total length using only complete isolated elements. D, OLS regressions of total length against minimum diaphyseal circumference using only complete isolated elements. SMA statistics are presented in Supplementary Table S2-2. OLS statistics are presented in Supplementary Table S2-

141 142

142 143

Supplementary Figure S2-2. Size-frequency distributions of hadrosaurid radii (A, B), ulnae (C,

D), and fibulae (E, F) from the Dinosaur Park Formation (DPF) of Alberta, Canada. A, C, E,

Total length. B, D, F, Minimum diaphyseal circumference. Tick marks below each size- frequency distribution correspond with individual bones. Dark shade represents raw measurement values; light shade represents estimated values based on an Ordinary Least Squares

(OLS) regression between total length and minimum diaphyseal circumference (Supplementary

Table S2-3, Supplementary Figure S2-1C, D).

144

145

Supplementary Figure S2-3. Size-frequency distributions of humeral (A) and femoral (B) minimum diaphyseal circumferences integrated with osteohistology. Estimated values were based on Ordinary Least Squares regressions (Supplementary Table S2-3, Supplementary Figure

S2-1C, D).

146

147

Chapter 3

Life history of Edmontosaurus annectens (Ornithischia:

Hadrosauridae) from the Late Cretaceous (Maastrichtian) Ruth

Mason Dinosaur Quarry, South Dakota, United States

Mateusz Wosik1 and David C. Evans1,2

1Department of Ecology and Evolutionary Biology, University of Toronto, 100 Queen’s Park,

Toronto, Ontario, M5S 2C6, Canada, [email protected]

2Department of Natural History, Royal Ontario Museum, 100 Queen’s Park, Toronto, Ontario,

M5S 2C6, Canada, [email protected]

148

3.1 Abstract

The Late Cretaceous (Maastrichtian) Ruth Mason Dinosaur Quarry (RMDQ) represents a monodominant Edmontosaurus annectens bonebed from the Hell Creek Formation of South

Dakota and has been determined as a catastrophic death assemblage likely belonging to a single population, providing an ideal sample to investigate hadrosaurid growth and population dynamics. For this study, size-frequency distributions were constructed from linear measurements of long bones (humeri, femora, tibiae) from RMDQ that revealed five relatively distinct size classes along a generally right skewed distribution, which is consistent with a catastrophic assemblage. To test the relationship between morphological size ranges and ontogenetic age classes, subsets from each size-frequency peak were transversely thin-sectioned at mid-diaphysis to conduct an ontogenetic age assessment based on growth marks and observations of the bone microstructure.

When combining these independent datasets, growth marks aligned with size-frequency peaks, with the exclusion of the overlapping subadult-adult size range, indicating a strong size-age relationship in early ontogeny. A growth curve analysis of tibiae indicated that E. annectens exhibited a similar growth trajectory to the Campanian hadrosaurid Maiasaura although attaining a much larger asymptotic body size by about nine years of age further suggesting that the clade as a whole may have inherited a similar growth strategy. When the RMDQ population was compared with size distributions from other hadrosaurid bonebed assemblages, juveniles

(ages 1 & 2) were either completely missing or heavily underrepresented providing support for the hypothesized segregation between juvenile and adult hadrosaurids. Osteohistological comparison with material from polar and temperate populations of Edmontosaurus revealed that previous conclusions correlating osteohistological growth patterns with the strength of

149 environmental stressors were a result of sampling non-overlapping ontogenetic growth stages.

Finally, the osteohistological assessment of Anatotitan revealed the sampled individual had attained the threshold for skeletal maturity, and when compared with the RMDQ population, it fell within the variation of growth for late adults of E. annectens.

3.2 Introduction

Osteohistology, which is the study of bone tissues, has been increasingly utilized in paleontological studies to reveal insights such as ontogenetic status, physiology, and annual bone deposition rates (e.g. Francillon-Vieillot et al. 1990; Padian 2013; Hall 2015). This has provided information unobtainable from morphology to attempt life history reconstructions of extinct animals (e.g. Erickson and Tumanova 2000; Erickson et al. 2006; Woodward et al. 2015), supported by observations of extant animals (e.g. Buffrenil and Castanet 2000; Woodward et al.

2011; Köhler et al. 2012). Some of the most detailed studies of dinosaur osteohistological variability have been conducted on hadrosaurids (Horner et al. 1999, 2000; Woodward et al.

2015). Horner et al. (2000) reconstructed a growth series of the hadrosaurid Maiasaura peeblesorum derived from contemporaneous nesting grounds, bonebeds, and isolated skeletons that would form a fundamental framework for future life history analyses of fossil taxa. From cross-sectional observations of growth marks (e.g. lines of arrested growth; LAGs) and patterns of bone tissue change, the authors established ontogenetic stages for relative size ranges across the complete lifespan of this taxon.

However, expansion and shape change of the medullary cavity due to biomechanical factors and physiological processes can obliterate growth marks representative of early ontogeny and result

150 in underestimations of ontogenetic age (e.g. Horner and Padian 2004; Cooper et al. 2008;

Woodward et al. 2013). To combat this, growth marks from an ontogenetic series can be sequentially stacked, but this generally requires a growth series of the same element (Chinsamy

1993; Erickson et al. 2001; Bybee et al. 2006). Alternatively, a quantitative model-fitting retrocalculation method was introduced by Cooper et al. (2008) that used a series of regression equations fit to plots of the measured circumferences of individual bones from Hypacrosaurus as a function of age to estimate the size of missing growth marks and has been demonstrated to be a more accurate measure than section-stacking (Chiba et al. 2015; Chiba 2018). Lee and O’Connor

(2013) later refined the retrocalculation method for the purpose of reconstructing growth rates.

Taking these new methods into account, Woodward et al. (2015) expanded on the initial

Maiasaura study by Horner et al. (2000) and integrated Developmental Mass Extrapolation

(DME) (Erickson and Tumanova 2000) to produce the first body mass growth curve for a hadrosaurid, further establishing Maiasaura as the most ontogenetically well understood dinosaur.

The life history synthesis from studies of Maiasaura (e.g. Horner and Makela 1979; Horner

1982; Varricchio and Horner 1993; Barreto 1997; Horner 1999; Dilkes 2000, 2001) has been broadly extrapolated to the hadrosaurid clade. However, that extrapolation has been made with minimal investigation into additional hadrosaurids despite an abundance of available material from numerous taxa. Edmontosaurus is one of the largest hadrosaurids with two currently recognized species, E. annectens and E. regalis, which are distinguished through subtle cranial morphologies and by their geographic distributions and temporal segregation (Campione and

Evans 2011; Xing et al. 2014, 2017). It is one of the best-sampled hadrosaurids known from over a dozen complete articulated skeletons across the entire ontogenetic sequence (Wosik et al.

2017b and references therein) and multiple monodominant bonebeds that preserve a wide

151 spectrum of ontogenetic stages and population samples (Christians 1992; Colson et al. 2004;

Gangloff and Fiorillo 2010; Bell and Campione 2014; Evans et al. 2015a; Ullmann et al. 2017).

The current fossil record of Edmontosaurus thus preserves one of the most extensive ontogenetic samples for any dinosaurian taxon making it ideal for life history studies of a fossil organism, even at the population level.

For our study, we conducted an ontogenetic osteohistological assessment of Edmontosaurus annectens from the Late Cretaceous (Maastrichtian, ~66-67 mya) Ruth Mason Dinosaur Quarry

(RMDQ), Hell Creek Formation of South Dakota, United States. The extensive preservation (>

10,000 bones) of this monodominant E. annectens bonebed (Christians 1992) allowed us to independently evaluate hadrosaurid growth and population dynamics and because of the non- selective nature of this catastrophic mass death assemblage (Christians 1992), representatives across ontogeny were preserved, presumably in proportions equivalent to the living population’s age structure (Olson 1957). The primary goals of this study were to (1) describe the ontogenetic osteohistological changes in the major limb bones of E. annectens, (2) reconstruct the growth rate and population structure of E. annectens, and (3) further assess the potential of using size- frequency distributions as a proxy for ontogenetic age in hadrosaurids (Brinkman 2014; Chapter

2). In addition, this study also supplied a reference point for reevaluating the suggested relationship between osteohistological patterns and environmental stressors in Edmontosaurus

(Chinsamy et al. 2012; Vanderven et al. 2014) and provided the first osteohistological data for testing the synonymy of Anatotitan as the ontogenetic endpoint of E. annectens (Campione and

Evans 2011).

152

3.3 Geological Setting

The Ruth Mason Dinosaur Quarry (RMDQ) is a monodominant Edmontosaurus annectens bonebed consisting of over 10,000 disarticulated bones of this taxon from the Hell Creek

Formation (Late Cretaceous: upper Maastrichtian, ~66-67 million years ago). It is located in

Ziebach County, South Dakota (Fig. 3-1), and was first discovered in the early 1900’s by Ruth

Mason. The RMDQ lies in the southern part of the Williston Basin and strata from the

Maastrichtian aged Fox Hills and Hell Creek formations are both visibly exposed here

(Christians 1992).

Based on data from taphonomic analyses (Christians 1992), the RMDQ was a pauci-specific, parautochthonous assemblage dominated by the disarticulated remains of E. annectens. Strong evidence of size-frequency profiles and limited subaerial exposure prior to burial based on uniform ‘stage 0’ weathering (Behrensmeyer 1978) of cranial and postcranial elements suggest a mass death of several hundred to perhaps thousands of E. annectens individuals (Christians

1992). Results from sedimentological analyses of the deposit demonstrated that the bone horizon recorded at least two depositional events. The lower half is indicative of a debris flow, identified through randomly oriented and upended bones comprising a poorly sorted and crudely graded assemblage of freshwater, fluvial fauna in addition to the dinosaurian remains (Christians 1992).

The upper half represents a characteristic floodplain deposit containing randomly distributed remains of terrestrial and freshwater organisms with strong similarities to fauna of the lower half.

The unique combination of the taphonomic and sedimentologic data exemplifies a catastrophic death assemblage characteristic of a debris flow that was secondarily redeposited locally

(Christians 1992).

153

The RMDQ has been excavated since 1979 by multiple institutions (Black Hills Institute of

Geological Research [BHI], University of Wisconsin-Madison [UWGM], University of Chicago, and The Children’s Museum of Indianapolis [TCM]) and has been subjected to varying degrees of excavation. Both BHI and TCM, from which the majority of specimens from our dataset originate, instituted exhaustive excavation protocols which significantly reduced biases related to collection (e.g. small vs. large, complete vs. incomplete). Detailed locality information of each specimen is on file at its respective institution.

3.4 Materials and Methods

The sample size of E. annectens long bones from the RMDQ consisted of a total of 639 specimens across all six major limb elements: femora 155, tibiae 130, fibulae 108, humeri 103, radii 82, and ulnae 61. In addition, 270 metacarpals and metatarsals were collectively analyzed as a taphonomic proxy for smaller limbs. Measurement data were gathered personally (MW) and from recorded field collection logs (Appendix 3-1). Completeness of bones was identified on the basis of general preservation and ability to obtain both the total length and minimum diaphyseal circumference measurements, and was categorized as complete, nearly complete, and incomplete. Linear measurements under 30 cm were taken with digital calipers, while those over

30 cm and all circumferences were taken using a fabric tape measure. Categorization of specimens followed published ontogenetic stages of the closely related hadrosaurid dinosaur

Maiasaura peeblesorum, recognized on the basis of relative size, patterns of histological changes, and associations with eggs and nests (Horner et al. 2000) and were then proportionately adjusted to account for the relatively larger size of Edmontosaurus at each ontogenetic stage

154

(Wosik et al. 2017b). RMDQ specimens used for osteohistological sectioning (Table 3-1) were excavated by BHI between 1979-1991 prior to acquisition by the Royal Ontario Museum. The right humerus of the Anatotitan (sensu Brett-Surman 1979) CCM V 1938.8 was histologically sectioned to evaluate its ontogenetic status.

3.4.1 Regression Analyses

In order to maximize sample sizes for size-frequency distributions, Ordinary Least Squares

(OLS) regressions between the total length and minimum diaphyseal circumference of complete humeri, femora, and tibiae from the entire RMDQ dataset of each respective major limb element were used to estimate the size of the corresponding variable for incomplete elements. The purpose of this was to include valuable data from incompletely preserved or obstructed (e.g. half jackets) specimens and subsequently increase the overall sample size. This procedure was not performed on radii, ulnae, and fibulae because the minimum diaphyseal circumference can significantly vary ontogenetically along the proximal-distal axis (personal observation) and would introduce bias unless properly controlled. Linear data were log-transformed prior to analysis using natural log (ln). Slopes, intercepts, 95% confidence intervals, and correlation coefficients were determined for each comparison. Each comparison was then evaluated using two-tailed p-values using a significance level of 0.05 for correlation between variables. The regressions and statistical analyses were performed in R (R-Development-Core-Team 2016) with the package ‘lmodel2’ (Legendre 2013).

3.4.2 Size-Frequency Distributions

Individual size-frequency distributions of total length and minimum diaphyseal circumference were generated in R (R-Development-Core-Team 2016) using the entire dataset for humeri,

155 femora, and tibiae, whereas only total length was analyzed for ulnae, radii, and fibulae. For relative scale, the largest corresponding element from RMDQ was used to represent a presumably morphologically adult-sized specimen of E. annectens with an approximate body length of 12 meters. Combined size-frequency distributions consisted of data from humeri, femora, and tibiae. In addition, a collective size-frequency distribution of metacarpals and metatarsals was generated to test whether nestling and early juvenile individuals, whose limb bones were hydraulically similar, were sorted out taphonomically. To determine whether our size-frequency distributions were sensitive to size and the amount of bins, we attempted to optimize these values using the method of Shimazaki and Shinomoto (2007, 2010). The resulting range of values was then utilized as a guideline when applying the broken stick method to each individual size-frequency distribution. A general average of approximately 25 bins was determined to be optimal among the size-frequency distributions.

3.4.3 Osteohistology

In order to generate a growth curve and assess growth rate variation, a total of 15 RMDQ specimens consisting of four humeri, four femora, and seven tibiae from the ROM collections were histologically thin-sectioned at the minimum diaphyseal circumference (see Table 3-1 for list of sampled specimens). Specimens for histological sectioning were selected from each size- frequency peak based on outer circumference to assess correlation between size and age. Thin sections were made and imaged at the ROM Palaeohistology Laboratory, and all molding and casting materials and thin-sections were deposited at the ROM. Materials associated with the

CCM V 1938.8 Anatotitan humerus were accessioned at the CCM. Histological terminology follows that of Francillon-Vieillot et al. (1990). Cross-polarized filters were used to diagnose the orientation of collagen fibers (e.g. lamellar, parallel-fibered, woven-fibered). Vascular

156 orientation is used to describe how the long axes of vascular canals are oriented in the bone matrix (e.g. longitudinal, radial, reticular, plexiform, laminar). Cyclical growth marks were diagnosed based on a variation or pause in the rate of bone growth and were used to determine the age and growth rates of sampled individuals. Lines of arrested growth (LAGs), a type of cyclical growth mark, were identified based on an attenuation or complete cessation in bone deposition, which would be visible along the circumference of the section. A zone represented the bone deposition region in between growth marks.

3.4.3.1 Thin-sectioning Protocol

Prior to sectioning, specimens were mechanically prepared with pneumatic and hand tools to remove surrounding rock matrix. Each specimen was measured and photographed, and three- dimensional models were generated using Agisoft PhotoScan. Complete cross-sectional thin- sections were produced using the standard fossil histology techniques (e.g. Lamm 2013) as a guideline and modified as necessary to the requirements of the specimen and/or available equipment. Complete cross-sectional pucks including the minimum diaphyseal circumference were cut out using a Well diamond-plated wire saw or Buehler IsoMet 1000 Precision Cutter low-speed saw depending on the size of the specimen. The pucks were molded and casted and casts were then reinserted into the original bone. The pucks were completely embedded in

Castolite polyester resin, cut on a Buehler IsoMet 1000 Precision Cutter low-speed saw, and mounted on 2-3 mm plexi-glass slides with PSI 122/124 resin. The blocks were then cut off the slides on the IsoMet, and the slides were subsequently ground down to the appropriate thickness to view overall bone microstructure using either a Hillquist Thin Sectioning Machine or grinding lap wheel. Slides were finished by hand polishing on a glass plate with 600 followed by 1000

157 silicon carbide grit and briefly placed into a sonic-bath to further remove any remaining grit and debris before imaging.

3.4.3.2 Imaging Protocol

Thin-section images were made using a Nikon DS-Fi1 camera mounted to a Nikon AZ-100 microscope under plain-polarized and cross-polarized. Images were processed and assembled using Nikon NIS-Elements Basic Research 3.13 imaging software. Images were taken at variable magnifications dependent on specimen size, 1280x960 resolution, 2.9-8 millisecond exposure, and set on Dynamic contrast with 35-40% overlap. Johnson & Johnson baby oil was added to each slide to increase the refraction index for clarity during imaging. Multiple images were taken for slides that exceeded the focal dimensions of the imaging stage and later stitched together using the Automate>Photomerge feature in Adobe Photoshop. Further processing of images (e.g. text, scale bars) and retrodeformation was completed using Adobe Photoshop and Adobe

Illustrator. Retrodeformation, which is the digital reconstruction of histological thin-sections, was performed to better recover a more accurate size and shape of the cross-sectional samples

(Fig. 3-2). This is an important step that is often overlooked when determining whether gaps along the circumference are indeed due to missing pieces of bone and/or a result of distortion from taphonomic processes, particularly in the case of lateral compression. The degree to which this process was required was dependent on the level of preservation of each specimen.

3.4.4 Age Determination and Growth Modeling

In order to account for the entire growth history, age retrocalculation (Cooper et al. 2008) was performed on tibiae with the longest growth record (ROM 73852, 73853) to identify any potentially missing growth marks, or growth years. Retrocalculation and growth modeling was

158 restricted to tibiae so our data could be compared with previously published growth rates of other hadrosaurids (Cooper et al. 2008; Freedman Fowler and Horner 2015; Woodward et al. 2015;

Chapter 2). Tibia circumference and body mass growth curves were individually generated for these two tibiae as well as a combined dataset of all recorded tibial growth marks using

Richards-family growth models (Lee and O’Connor 2013) in R (R-Development-Core-Team

2016). Corrected Akaike Information Criterion (AICc) values were used to account for small sample sizes using R package ‘MuMIn’ (Bartoń 2017). Next, delta AICc (ΔAICc) and AICc weight values were calculated to obtain averaged models for each specimen (Burnham and

Anderson 2002). Obtaining an averaged model is important when AICc values of individual models are within ten ΔAICc, which deems each individual model as plausible (Burnham and

Anderson 2002). Finally, the retrocalculated ages obtained from the averaged model for the combined dataset were considered as the precise age of growth marks and applied in the tibia circumference and body mass growth curve analyses. An estimated yearling tibial circumference of 100 mm was required to calibrate the curve at the early ontogenetic stage (Chiba 2015), and was obtained by using the recorded yearling growth mark of a hadrosaurid from the Dinosaur

Park Formation (Chapter 2) and applying the proportionate difference between Maiasaura and

Edmontosaurus nestlings (Wosik et al. 2017b). This was done because the retrocalculation on the individual tibiae was estimating growth years that were not present in the histological record, even in the younger individuals where secondary osteon development was very minimal, if present, in the cortical bone. An osteohistologically determined tibial hatchling circumference of

25 mm was used for each age retrocalculation model (Wosik et al. 2017c). Age was also cross- checked via section-stacking of growth marks, or annuli, (Bybee et al. 2006) from the histological samples in this study whenever possible. Transverse section periosteal surfaces

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(outer circumference) and circumferences of growth marks were traced in Adobe Illustrator.

Data for tibiae of hadrosaurids used for comparison were obtained from Chapter 2.

An interspecific equation for quadrupedal vertebrates (Campione and Evans 2012: Equation 1) was used to estimate the body mass of SM R4050, which has a femur circumference of 460 mm.

This specimen was selected to represent a presumably morphologically adult individual for growth modeling rather than the holotype, USNM 2414, because it is the largest irrefutable associated skeleton of E. annectens that preserves complete and unobstructed circumferences for humeri and femora, which are required parameters for the interspecific equation. Developmental

Mass Extrapolation (DME) (Erickson and Tumanova 2000) was then used to convert tibial growth mark circumferences to body mass to account for deviations from the body mass equation for juvenile individuals.

3.5 Results

The level of preservation varied between the elements, which were preserved in a soft but iron- rich matrix that could be particularly seen around the terminal ends and, in rare cases, extensive pyritization had formed in the medullary cavity. All femora exhibited a high degree of lateral compression, especially along the shaft region, but despite this extensive crushing, the femoral head, trochanters, and distal condyles preserved their natural shapes in each individual along with clear signs of cartilaginous cap attachments in larger individuals. Humeri were less compressed than the femora, but occasionally distorted in a spiral manner along the proximal- distal axis with the deltopectoral crest folding in on itself. Larger individuals better preserved the natural shape of the humerus, whereas smaller individuals would often have both an eroded humeral head and distal condyles or completely lacked one or both of their terminal ends. Tibiae

160 were generally well preserved with only a few cases of minor spiral torsion along the shafts. This taphonomic variability may have resulted from the stylopodial elements having larger medullary cavities relative to the cortical bone thickness rendering them to be more prone to crushing than the dense tibiae. However, the proximal ends were consistently weathered or compressed making the distinction between condyles more difficult if the cnemial crest was not clearly preserved.

Despite these differences, nearly all bones preserved a beautiful glossy texture on the periosteal surface regardless of size indicating that little, if any, of the periosteal surface was missing or had eroded/weathered away.

Of the 639 limb bones from the RMDQ analyzed in this study (Appendix 3-1), 626 (~98%) had measurable complete total lengths. The humerus sample consisted of 103 bones, of which 103 and 34 had measurable complete total lengths and minimum diaphyseal circumferences, respectively. Only 31 humeri had both variables that were measurable because a large portion of the sample was in half jackets, and therefore, obstructed circumference measurements. The femur sample consisted of 155 bones, of which 154 and 17 had measurable complete total lengths and minimum diaphyseal circumferences, respectively, and only 16 had both variables that were measurable. The tibia sample consisted of 130 bones, of which 129 and 28 had measurable complete total lengths and minimum diaphyseal circumferences, respectively, and 27 had both variables that were measurable. The remaining elements were only analyzed in terms of total length.

3.5.1 Regression Analyses

Sample sizes of the OLS regression analyses (Supplementary Table S3-1) ranged from 16

(femur) to 31 (humerus) individually complete specimens. All comparisons presented high coefficients of determination (R2 > 0.94) and significant correlation between variables based on

161 low p-values (p < 8.47e-10). Therefore, estimation of incomplete elements could be confidently executed using the corresponding OLS regression values.

3.5.2 Size-Frequency Distributions

The combined total length size-frequency distribution (Fig. 3-3A, B) consisted of a combined total of 388 humeri, femora, and tibiae and revealed five relatively distinct size-frequency peaks along a right-skewed distribution. The smallest size class, which resembled more of a broad cluster than a peak, included 110 individuals that ranged from ~43–60% of the linear dimensions of the largest corresponding element length from RMDQ, with a general concentration in the

~50-60% size range. Articular surfaces were well defined when preserved and there were no signs of a porous periosteal surface, which instead exhibited a distinct sheen when fully prepared. Individuals in this size class would have had a body length ranging from 516-720 cm and corresponded with the late juvenile size class as defined in Horner et al. (2000) and proportionately adjusted for Edmontosaurus (Wosik et al. 2017b). The second size class consisted of 77 subadult individuals that ranged from ~62-70%, with a very distinct size- frequency peak in the ~65-67% size range, and would have corresponded with body lengths of

780-840 cm. The external morphology was similar to the late juvenile individuals except that attachment sites for muscles such as that along the fourth trochanter of the femur were much more defined. The third size class consisted of 61 subadult individuals that ranged from ~72-

79%. Using these data, the inclusive subadult size class of Horner et al. (2000) and Wosik et al.

(2017b) was split into two separate subadult size classes: early/small and late/large. Although we note that using early/late and small/large may not consider potential differences in size between sexes and intraspecific variation in growth, these terms were used to follow convention of currently established categorizations (Horner et al. 2000; Wosik et al. 2017b) until more data is

162 available to better refine the system. The fourth size class consisted of 39 adult individuals that ranged from ~82-89% with body lengths ranging between 984-1068 cm. Periosteal surface textures were very smooth emitting a natural sheen, muscle attachment sites were substantially robust and showed extensive signs of scarring, and articular surfaces were fully developed with large rugosities for cartilaginous cap attachments. The fifth size class consisted of 51 adult individuals that ranged in size from ~91-100%, which translated to individuals ~11-12 meters in body length, exceeding any currently estimated E. annectens skeleton (Wosik et al. 2017b). In a similar fashion to the inclusive subadult size class, this inclusive adult size class presented here was split into early/small and late/large constituents.

The combined minimum diaphyseal circumference size-frequency distribution (Fig. 3-3C, D) reflected the results of the combined total length size-frequency distribution with the general trend exhibiting a right skewed pattern where there was a progressive decrease between each proceeding size class. Size classes from the combined minimum diaphyseal circumference size- frequency distribution presented minor variations in their size ranges from those of the total length size-frequency distribution. When the dataset for the combined size-frequency distributions was partitioned into individual elements (Figs. 3-4 and 3-5) for total length and minimum diaphyseal circumference, it was not possible to accurately discern where one size class ended and another began. Although size-frequency peaks were recognizable in each size- frequency distribution, the amount of size-frequency peaks was not consistent among all the individual size-frequency distributions. However, the generally right-skewed trend as seen in the combined size-frequency distributions was apparent among all elements except for the ulna, which had the smallest sample size (n = 61).

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When superimposing associated skeletons, the late juvenile LACM 23504 consistently placed either within or just before the first size class (late juvenile) in all of the size-frequency distributions. The largest skeletons, AMNH 5730 and CCM V 1938.8 (referred to Anatotitan

[sensu Brett-Surman 1979]), placed within the late adults among all six total length size- frequency distributions. However, these same skeletons placed beyond the largest RMDQ minimum diaphyseal circumferences suggesting that there may be a source of bias offsetting the circumference results or that the reported circumference measurements of the selected associated skeletons may be inaccurate. The offset could also be reflecting differences between growth strategies, but it is more likely to be an artifact of crushing in the RMDQ assemblage.

Curiously, the minimum extent for both of the combined size-frequency distributions was about

40% of the largest corresponding element from RMDQ. Therefore, a size-frequency distribution of autopodial elements (metacarpals and metatarsals) was generated to provide a basis for testing whether the size range of nestling to juvenile individuals, whose limb bones were hydraulically similar to the autopodial elements, were transported out taphonomically via hydraulic action.

When superimposing associated skeletons of E. annectens on the collective size-frequency distribution of metacarpal and metatarsal total lengths (Fig. 3-6), the metatarsal III of the late juvenile LACM 23504 placed at the leftmost extent of the metatarsals from RMDQ, but most importantly, femur lengths of nestlings from E. annectens (UCMP 128181) (Wosik et al. 2017b) and Maiasaura (YPM-PU 22432; YPM-PU 22400) (Horner et al. 2000) placed well within the left tail of the size-frequency distribution that consisted of ~38 equivalently sized autopodial elements.

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3.5.3 Osteohistology

All osteohistologically sampled specimens preserved complete cross-sections and are listed in

Table 3-1. Categorization of specimens followed published ontogenetic stages for hadrosaurids

(Horner et al. 2000; Wosik et al. 2017b) and was further split using the size-frequency distribution data presented herein. Five growth stages were recognized with the RMDQ sample: late juveniles, early subadults, late subadults, early adults, and late adults. As mentioned above, we understand that early/late and small/large may not account for potential differences in size between sexes and intraspecific variation in growth. However, these terms were tentatively used to follow convention of currently established categorizations (Horner et al. 2000; Wosik et al.

2017b) until more data is available to better refine the system. The osteohistology of forelimb elements (humerus) is presented first and followed by elements of the hind limb (femur, tibia).

Each element is then separated into size classes. The osteohistology of the right humerus of

Anatotitan CCM V 1938.8 is presented later in the discussion.

3.5.3.1 Humerus

3.5.3.1.1 Late Juvenile

Specimen examined: ROM 73849 (Fig. 3-7A, B). The mid-diaphyseal perimeter was elliptical in cross-section but was slightly crushed. An identical pattern was reflected in the shape of the medullary cavity, which was substantially cancellous with very large cancellous spaces relative to the cortical bone and composed 37.5% of the surface area of the entire cross-section. The inner cortex was largely composed of highly disorganized woven-fibered bone based on its isotropic pattern under cross-polarized light; an endosteal margin of the compact bone was not identifiable. The cortical bone, or compacta, was composed of primary bone tissues with

165 reticular vascular canal orientation that, going outwards, shifted into plexiform and finally into a sub-laminar, or nearly circumferential, orientation at the periosteal surface. The main component of the compacta was parallel-fibered bone, which was highly anisotropic, with some instances of woven-fibered bone particularly at the interface between the cortical bone and the medullary cavity. There were no signs of growth marks or secondary osteon development but enlarged resorption cavities were present within the medullary cavity and inner cortex regions.

3.5.3.1.2 Early Subadult

Specimen examined: ROM 67796 (Fig. 3-7C, D). When retrodeformed, the mid-diaphyseal perimeter resembled a triangular-like shape with well-rounded corners and convex edges. The medullary cavity, which composed 45.4% of the cross-sectional area, reflected the triangular shape of the periosteal perimeter and was more cancellous with larger vascular canal spaces than the late juvenile (ROM 73849). Fibrolamellar bone, defined as a ‘complex of woven-fibered scaffolding with intervening primary osteons of varying orientations’ (Huttenlocker et al. 2013), composed the majority of the medullary cavity bone tissues; under cross-polarized light, erosional cavities were lined with dense lamellar bone in which the collagen fibrils alternated their depositional direction between concentric layers. An endosteal margin of the compact bone was not identifiable, a likely result of the expanding medullary cavity. The cortical bone was composed of primary parallel-fibered bone tissues with several zones of vascular canals shifting from plexiform to laminar orientation. Between each zone was a cyclical growth mark, or annulus, similar to those observed in Maiasaura (Woodward et al. 2015), in that a clear cessation in bone deposition was not visible but instead consisted of a narrow transition of parallel- fibered/lamellar bone with weakly anastomosing vascular canals; two such growth marks were present with a third beginning to develop at the periosteal surface, as evidenced by the layering

166 of parallel-fibered bone with laminar vascular canal orientation. Varying sizes of secondary osteons each with a distinct cement line were scattered throughout the medullary cavity region and began to invade the interface between the cortical bone and the medullary cavity.

3.5.3.1.3 Late Subadult

Specimen examined: ROM 73850 (Fig. 3-7E, F). The mid-diaphyseal perimeter resembled the triangular-like shape of the early subadult (ROM 67796), but the edge corresponding with the medial side of the bone was substantially flattened and as a result, elongated the cross-section antero-posteriorly. The medullary cavity formed an elliptical shape that composed only 34.7% of the cross-sectional area and had a similar degree of cancellous bone as the late juvenile (ROM

73849). Fibrolamellar bone composed the majority of the medullary cavity bone tissues as well as the interface leading up to the cortical bone. The cortical bone was composed of primary parallel-fibered bone tissues with several zones of vascular canals shifting from plexiform to laminar orientation. Three growth marks, similar to those observed in the early subadult (ROM

67796), were present separating each zone with laminar vascular canal orientation. Closest to the periosteal surface, there was a more prominent layering of parallel-fibered/lamellar bone with laminar vascular canal orientation. Secondary osteons with multiple cement lines had fully invaded the cortical bone up to about the first growth mark (147 mm) and were slightly scattered within the next zone up to the second growth mark (173 mm). A Haversian system of overlapping generations of secondary osteons (Reid 1985) was beginning to develop along the lateral side of the humerus at the interface between the medullary cavity and cortical bone.

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3.5.3.1.4 Late Adult

Specimen examined: ROM 67794 (Fig. 3-7G, H). The mid-diaphyseal perimeter reflected the same shape of the late subadult (ROM 73850) but was more elongated antero-posteriorly. The medullary cavity formed an elliptical shape that composed 36.8% of the cross-sectional area, similar to the late juvenile and late subadult stages. The core of the medullary cavity was not preserved and left a large vacant space void of any matrix. The remainder of the medullary cavity was completely obliterated by multi-generational Haversian bone systems (Reid 1985) that extended into the cortical bone up to about the third growth mark (215 mm). Although this level of secondary remodeling had obscured portions of the two preceding growth marks (178 and 196 mm), enough of each was identifiable to accurately piece together the two respective circumferences. The cortical bone after the third growth mark was composed of a lamellar bone matrix that occasionally transitioned between parallel-fibered bone. Each zone primarily consisted of laminar vascular canal orientation with narrow regions of plexiform orientation.

Secondary osteons each with a single cement line were scattered throughout the remainder of the cortex and were occasionally present near the periosteal surface. The fifth growth mark (234 mm) exhibited a clear cessation in bone deposition as evidenced by an uninterrupted line around the entire circumference of the bone section and was defined as the first LAG. The six LAGs that followed alternated between a similarly uninterrupted line and/or a semi-translucent opaque band within a lamellar bone matrix that consisted of very tightly stacked laminar vascular canals; these final six LAGs could potentially be referred to as an external fundamental system (EFS) (Horner et al. 2000) or outer circumferential layer (OCL) (Chinsamy-Turan 2005), which signals skeletal maturity.

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3.5.3.2 Femur

3.5.3.2.1 Late Juvenile

Specimens examined: ROM 67602 (Fig. 3-8A, B), ROM 67798 (Fig. 3-8C, D). After retrodeformation, the mid-diaphyseal perimeter of ROM 67602 had an elliptical shape with a relatively broad minimum axis, whereas ROM 67798 has a more circular shape with rounded corners near the region of the fourth trochanter. The medullary cavities, which composed ~33% of the entire cross-sectional area in each specimen, reflected the shapes of their respective periosteal perimeters. Because the femora were heavily distorted from crushing, the medullary cavities of each specimen composed of a large central void. However, the preserved portions near the interface between the medullary cavity and the cortical bone distinctly consisted of large erosional cavities transitioning into relatively smaller constituents when moving outwards and into the cortical bone. ROM 67798 best presented this graduated transition, which halted shortly before the single recorded growth mark (226 mm), whereas the smaller erosional cavities continued up to the periosteal surface in ROM 67602; an endosteal margin of the compact bone was not identifiable in either specimen. Much of what was preserved of each medullary cavity and the majority of the cortical bone was composed of fibrolamellar bone with an underlying woven-fibered matrix organized in a reticular orientation that was overprinted by lamellar bone particularly around erosional cavities. Parallel-fibered bone composed the outermost cortex with a transitioning plexiform-laminar vascular canal orientation as seen in the late juvenile (ROM

73849) and early subadult (ROM 67796) humeri. Because both femora had similar outer circumferences of ~253 mm, we expected them to also have similar growth mark records.

However, only ROM 67798 recorded a single growth mark with a similar narrow zone of parallel-fibered/lamellar bone as in the early subadult humerus (ROM 67796), but both femora

169 preserved a layering of lamellar bone with laminar vascular canal orientation at the periosteal surface. ROM 67602 presented signs of localized parallel-fibered bone in the region of the ROM

67798 growth mark, but did not continue around the entire circumference. Secondary osteon development was completely absent throughout each cross-section except for the area near the fourth trochanter. Here, secondary osteons with a single cement line were elongated on a diagonal to the perpendicular surface of the nearby periosteal surface and looked as though they were being ‘pulled’ towards the muscle attachment site.

3.5.3.2.2 Early Subadult

Specimen examined: ROM 67799 (Fig. 3-8E, F). Similar to the late juvenile femora (ROM

67602, 67798), this specimen had undergone extensive crushing and required retrodeformation.

The mid-diaphyseal perimeter and general outline of the medullary cavity were similar to the circular shape of the late juvenile (ROM 67798) but with more defined corners along the anterior side. The medullary cavity composed 58.9% of the entire cross-sectional area with a very large central void as a result of the crushing. Erosional cavities considerably ranged in size and persisted up until the first growth mark (272 mm) within a substantially remodeled bone matrix that consisted of lamellar bone around the circumference of each erosional cavity. Secondary osteons recorded multiple generations (3+) of cement lines and exhibited exquisite Maltese cross extinction patterns when the cross-polarized filter was rotated. Dense Haversian bone (Reid

1985) was present along the posterior half of the cross-section, particularly in the area of the fourth trochanter, which obscured the growth record in these regions. However, the remainder the outer cortex of the posterior half and the entire cortical bone of the anterior half of the bone recorded three transitionary plexiform-laminar vascular canal orientation zones separated by two growth marks. Parallel-fibered bone composed the plexiform oriented portions, whereas the

170 laminar regions, which included the growth marks, were composed of lamellar bone with interspersed areas of parallel-fibered bone. Prior to the second recorded growth mark (296 mm), the plexiform region exhibited sparsely scattered secondary osteons of varying sizes that continued around the circumference of the cross-section, even in areas of dense secondary osteon development. The outermost cortex near the periosteal surface preserved a layering of parallel- fibered/lamellar bone with laminar vascular canal orientation at the periosteal surface.

3.5.3.2.3 Early Adult

Specimen examined: ROM 67792 (Fig. 3-8G, H). Retrodeformation was again required because of the substantial level of crushing. The mid-diaphyseal perimeter and general outline of the medullary cavity were also circular in shape but with corners that were more rounded than any of the younger ontogenetic stages. The medullary cavity composed 67.8% of the entire cross- sectional area with a substantially larger void resulting in a relatively thin layer of cortical bone.

Erosional cavities ranged in size and plentifully persisted up to just before the first growth mark

(336 mm), where there were almost no erosional cavities within a parallel-fibered/lamellar bone matrix running parallel with the growth mark. Prior to the first growth mark, any sign of primary bone tissue had been completely obliterated by extremely dense Haversian bone (Reid 1985).

Interestingly, the diameter of the secondary osteons exhibited a substantial reduction when approaching the first growth mark relative to more inner matrix. The zone continuing outwards from the first growth mark was composed of primary parallel-fibered bone with plexiform vascular canal orientation that was interspersed with erosional cavities; these ranged in size from small along the anterior and lateral sides of the bone to large on the medial and posterior side of the bone, which was closest to the muscle attachment sites and the fourth trochanter. Just prior to the second growth mark (367 mm), the vascular canal orientation shifted from plexiform to form

171 a narrow layer of laminar oriented lamellar bone. The next zone consisted of a sequence that started with two distinctly narrow bone layers that were present along the circumference of the section; the first was a layer of plexiform oriented parallel-fibered bone which was followed by a reticular oriented parallel-fibered layer that was about twice the thickness of the plexiform oriented layer. From the reticular orientation, the vascular canals briefly transitioned through plexiform before arriving at laminar, all while being composed of lamellar bone. This sequence of transitions is best seen along the anterior side of the specimen. The third growth mark (385 mm) was similar to those in younger individuals where there was no distinct break in bone deposition but rather a substantial reduction. In addition, the second and third growth marks had an opaque color that was consistently present across the entire circumference, even through the heavily remodeled region around the fourth trochanter. The outermost zone was strictly composed of lamellar bone with long laminar vascular canals and intermittent regions of plexiform orientation. Secondary osteon development was not present in the second, third, and fourth zones, which were adjacent to the third growth mark, except for regions near muscle attachment sites.

3.5.3.3 Tibia

3.5.3.3.1 Late Juvenile

Specimens examined: ROM 67601, ROM 67603 (Fig. 3-9A, B). After retrodeformation, the mid-diaphyseal perimeters of both cross-sections had a circular shape with a rounded corner along the anterolateral side of the bone. This anterolateral corner exhibited a radial strip

(Woodward et al. 2015) or anterolateral plug (Hübner 2012) of radially oriented vascular canals originating from the innermost cortex to the periosteal surface. The external morphology

172 indicated light scarring similar to other muscle attachment sites such as those along the fourth trochanter of femora. The medullary cavities, which composed ~26% of the entire cross- sectional area in each specimen, reflected the shapes of the near circular periosteal perimeters.

The medullary cavity of ROM 67601 was filled in with what perhaps resembled primary trabecular bone that was extremely cancellous, but this could have also been a product of taphonomic deformation. Conversely, the core of the medullary cavity of ROM 67603 did not preserve, and as a result was observed as a voided space. Endosteal margins of the compact bone were not identifiable in either specimen. Moving outwards towards the inner cortex of the bone, large erosional cavities of similar size were present along the circumference at the interface between the medullary cavity and cortical bone. A gradual reduction in size and density of these erosional cavities was observed through the inner half of the cortical bone and were no longer present in the outer half. A woven-fibered matrix of reticular oriented vascular canals composed the majority of the inner cortex that contained the erosional cavities. The outer cortex exhibited a transition from reticular oriented woven-fibered bone to plexiform oriented parallel-fibered bone with localized regions of laminar orientation near the periosteal surface. Although no complete growth marks were present in either of the two specimens, minor indications of a growth mark just outside of the medullary cavity region were observed in both. Tracing the entire circumference of this potential growth mark was not possible because it would waver between the medullary cavity and highly vascular inner cortex, but a coarse estimate was likely around

~100 mm. Secondary osteon development was absent in both specimens.

3.5.3.3.2 Early Subadult

Specimens examined: ROM 67795 (Fig. 3-9C, D), ROM 67797. The mid-diaphyseal perimeter of 67795 was very similar to the late juvenile tibiae (ROM 67601, 67603) but with a slightly

173 more pronounced anterolateral corner. The cross-sectional perimeter of ROM 67797 was egg- shaped, even after retrodeformation, with the rounded point being home to the location of the anterolateral plug suggesting that the section was taken slightly distal of the minimum diaphyseal circumference of the tibia. The medullary cavities, which composed ~25% of the entire cross- sectional area in each specimen, reflected the shapes of the respective periosteal perimeters. The anterior side of ROM 67795 had been crushed to the point that much of the cortical bone had caved invades towards the medullary cavity region and what remained after retrodeformation was sparse and likely misplaced effectively resulting in large voids. Given this, the outline of what was likely the medullary cavity was still recognizable and reflected the periosteal perimeter. The medullary cavity of ROM 67797 did preserve highly vascular trabecular bone along the anteromedial side of the element. Both specimens exhibited the same erosional cavity pattern at the interface between the medullary cavity and cortical bone as observed in the late juveniles (ROM 67601, 67603). The difference was that the pattern diminished just before the growth mark (202 mm) in ROM 67795 but well before in ROM 67797 almost never invading the cortical bone. This dissimilarity could be due to the difference in location of each cross-section along the proximal-distal axis of tibial diaphysis. Both medullary cavities were composed of woven-fibered bone with lamellar bone outlining each erosional cavity. Secondary osteons had begun to invade from the medullary cavity with secondary osteons that had as many as four generations of cement lines, but overlap between secondary osteons was not observed. The inner cortex was comprised of fibrolamellar bone with a dense woven-fibered component that was oriented with reticular vascular canals, and occasionally an intermediate stage between radial and reticular. Shortly before the one recorded growth mark in each specimen, the typical transition of reticular to plexiform to laminar vascular canal orientation was observed. The circumferential region of laminar orientation just before the growth mark was composed of lamellar bone with a

174 woven-fibered overprint scattered along the circumference. Following the growth mark, the bone transitioned into a narrow zone of parallel-fibered bone oriented with plexiform vascular canals before returning to the distinctive reticular orientation within a fibrolamellar matrix. As with the late juveniles, both early subadults exhibited a layering of parallel-fibered/lamellar bone with laminar oriented vascular canals near the periosteal surface.

3.5.3.3.3 Early Adult

Specimen examined: ROM 67793 (Fig. 3-9E, F). The mid-diaphyseal perimeter continued the trend of an overall circular shape with a rounded anterolateral corner, which was the only location in the cross-section with radial vascular canal orientation reflecting the characteristics of the anterolateral plug. The medullary cavity, which composed of 23.5% of the entire cross- sectional area, reflected the shape of the near circular periosteal perimeter. It was partially filled in with cancellous trabecular-like bone composed of a woven-fibered matrix and lamellar bone along the circumference of each erosional cavity. The transition from large to small erosional cavities was quite narrow and was minimally present in the inner cortex up until about the first growth mark (213 mm). The inner cortex was composed of a woven-fibered matrix oriented with reticular vascular canals and went through a very narrow region of plexiform before laying down distinct laminar oriented parallel-fibered bone leading up to the first growth mark. The next zone went through a sequence starting with reticular oriented woven-fibered bone, followed by a plexiform oriented woven/parallel-fibered complex, back to reticular oriented woven-fibered bone, before culminating with laminar oriented parallel-fibered bone. The second growth mark

(249 mm) exhibited relatively less separation from the previous zone than the first growth mark and was followed by laminar to plexiform oriented parallel-fibered bone that transitioned into

175 lamellar near the periosteal surface. Secondary osteon development was minimally present before the first growth mark and not observed in the outer cortex.

3.5.3.3.4 Late Adult

Specimens examined: ROM 73852, ROM 73853 (Fig. 3-9G, H). The mid-diaphyseal perimeter of ROM 73852 reflected the overall circular shape and rounded anterolateral corner of smaller size classes. The medullary cavity, which composed of 20.6% of the entire cross-sectional area, was nearly circular and did not extend into the anterolateral corner. It was partially filled in with cancellous trabecular-like bone composed of a woven-fibered matrix and lamellar bone along the circumference of each erosional cavity. Little or no transition from large to small erosional cavities was observed along the circumference of the medullary cavity. Immediately following was a dense inner cortex composed of a woven-fibered matrix with lamellar bone outlining a nominal array of small erosional cavities. This region was beginning to develop extensive secondary remodeling with a concentration of secondary osteons gradually increasing towards the anterolateral corner, which itself exhibited a dense stream of Haversian bone (Reid 1985) that continued until about the final 0.5 cm of the outer cortex. A total of twelve growth marks were recorded. Those within the inner cortex reflected zonal bone and vascular canal orientation changes similar to juveniles and early subadult individuals. Zones within the outer half of the cortex no longer retained a reticular component and were strictly transitioning between plexiform and laminar oriented parallel-fibered bone. The final three growth marks were LAGs and present in the last 0.5 cm of the cortex, which was composed of lamellar bone with some regions along the circumference exhibiting longitudinal vascular canal orientation.

The osteohistology of ROM 73853 was similar in many respects to ROM 73852, but several differences were observed. The anterolateral corner of the outer perimeter was much less

176 prominent giving the overall shape of a cross-section a near circular outline. Although secondary osteons were abundantly scattered throughout the entire cortex including the periosteal surface, enough of the primary bone tissue had not yet been obliterated and preserved a growth record of

~18 circumferential growth marks. Secondary osteons were commonly observed lining up alongside the growth marks. The final 6-8 growth marks were LAGs and were present within the last 1 cm of the outer cortex. Two potential instances of double LAGs were observed within the outer layering of growth marks but were tentatively considered as independent growth cycles due to the current lack of understanding surrounding multiple annuli within individual zones (e.g.

Evans et al. 2015b; Freedman Fowler 2015). In addition, several of these growth marks were only present along the postero-medial half of the cross-section and may not have been observed if only a partial cross-section or core was taken. The outer layering of LAGs near the periosteal surface resembled an EFS (Horner et al. 2000) or OCL (Chinsamy-Turan 2005) and presented an increase in erosional cavities relative to the majority of the cortical bone.

3.5.4 Age Determination and Growth Modeling

Data related to parameter values of each growth model for tibia circumference and body mass are available in Supplementary Table S3-2 and Supplementary Table S3-3, respectively. Growth mark circumferences for each sampled specimen are included in Table 3-1. A summary of estimated body masses for associated skeletons of Edmontosaurus is available in Table 3-2.

Tibia circumference and body mass growth curves are presented in Figure 3-10. From our

RMDQ sample, two tibiae preserved a substantial growth record that was suitable for growth modeling.

Retrocalculation was first performed on the individual tibiae, and then combining the growth record of both individuals to better represent the population. The averaged models indicated that

177 the first recorded growth marks of ROM 73852, ROM 73853, and the combined sample corresponded with 8.19, 4.71, and 4.35 years of age, respectively. These estimates were excessively high and outside of the range of variation relative to other hadrosaurids (Chapter 2).

Using the equations produced from the retrocalculation models to estimate the circumferences of the presumably missing growth marks, the histological sections exhibited no signs of growth marks in the prescribed regions, although it might have been possible for the estimated growth marks to have fallen within heavily remodeled areas or within the medullary cavity region. To further investigate the problem, we took the recorded tibial circumference of the yearling growth mark (85 mm) in hadrosaurids from the Dinosaur Park Formation of Alberta, Canada (Chapter

2), and proportionately adjusted it for the larger size of Edmontosaurus (Wosik et al. 2017b).

This indicated that an approximate circumference of 100 mm represented the yearling growth mark of E. annectens in the RMDQ sample, and indeed the ~100 mm circumference nested within the outer boundary of the medullary cavity region of the smallest sampled RMDQ tibiae

(ROM 67601, 67603). Retrocalculation on the collective sample including this hypothetical 100 mm growth mark indicated that it corresponded with 0.55 years of age, which was better aligned with the osteohistological record presented herein. Therefore, the first recorded growth mark of each individual was determined to correlate with the second year of growth.

The discrepancy could have occurred for a number of reasons. First, the retrocalculation of the growth mark record of Hypacrosaurus, as presented in Chapter 2, was inaccurately estimating the missing age. Through manipulation of the data (e.g. removing the first recorded growth mark in other individuals), it was determined that more of the growth record at the earlier ontogenetic stages was required to accurately estimate the missing age and could have also been the case here. Second, the hatchling size used was that of hadrosaurids from the Dinosaur Park

178

Formation, which were generally smaller in terms of average adult body size. To test how sensitive the retrocalculated ages were to the hatchling size, the retrocalculation models were rerun using a slightly increased hatchling circumference of 35 mm, instead of 25 mm. The results indicated a 12% decrease when estimating the missing age and demonstrated that a more accurate hatchling size would likely return more accurate age estimations. Third, the two late adult tibiae used for growth modeling may have reflected substantially different growth strategies indicating a high level of variation within the population.

The combined population containing the hypothetical 100 mm growth mark was analyzed using the respective retrocalculated ages. Growth began to slow down after age six and 95% body mass was attained by about age nine. The growth trajectory between the two tibiae revealed a small degree of variation and so the presented growth curve was intended to be an average of the two individuals. The transition from growth acceleration to deceleration, or the growth inflection point, occurred at 1.67 years of age, which was similar to values of 1.40 years of age for that of

Maiasaura (Chapter 2 reanalysis of Woodward et al. 2015). The shape parameter m of the

Edmontosaurus growth curve resembled an intermediate between the monomolecular and von

Bertalanffy models (m = 0.48). The average asymptotic body mass of E. annectens individuals from the RMDQ was ~5595 kg.

3.6 Discussion

This study represents the most thorough attempt to date to assess growth and demography in an extinct dinosaur using a novel combination of size-frequency distributions and long bone histology. Late juvenile individuals of Edmontosaurus annectens from the Ruth Mason Dinosaur

179

Quarry (RMDQ), South Dakota, all had primary bone tissues exhibiting a large medullary cavity surrounded by highly vascularized, woven-fibered bone within the inner cortex indicating rapid growth. The vascularity of the outer cortex largely consisted of zonal bone, transitioning from reticular/plexiform into laminar demonstrating an undulating or stratified growth pattern. Sub- adults retained the highly vascularized, woven-fibered inner cortex. Prominent lines of arrested growth (LAGs) appeared in the outer cortex of only the most mature individuals (ROM 67794,

73852, 73853). However, nearly all individuals except for a few of the late juveniles exhibited growth marks comprising a narrow but gradational shift from laminar to reticular oriented vascular canals similarly observed in Maiasaura (Woodward et al. 2015). Adults had well developed secondary osteons, and the non-zonal outermost cortex was comprised solely of laminar oriented lamellar bone indicating the onset of skeletal maturity. Pronounced stacking of

LAGs was preserved indicating the adult individuals (ROM 67794, 73852, 73853) were approaching asymptotic body size. Late juveniles and sub-adults exhibited a stronger zonation of bone with consistent shifts between reticular and laminar oriented fibrolamellar bone than was seen in adults. All sectioned elements showed a layering of laminar oriented parallel-fibered or lamellar bone near the periosteal surface that signaled the imminent formation of a growth mark.

When integrating the osteohistological data with that from the size-frequency distributions, growth marks were generally offset from and occasionally larger than the outer circumferences

(periosteal surfaces) of individuals belonging to the size-frequency peak of the corresponding size-class (Fig. 3-3D). However, there was a consistent correlation between individual size- frequency peaks and clusters of growth marks indicating that the size-frequency peaks in the size-frequency distributions were likely outlining cohorts in this catastrophic assemblage. This pattern was prevalent early in ontogeny up until the late subadult stage, or third size-frequency peak, when age ranges based on growth marks began to overlap. Individuals sampled from the

180 first size-frequency peak either recorded one growth mark or exhibited a distinct layering of laminar vascular canals near the periosteal surface suggesting the imminent formation of a growth mark; this annulus was approximately the size of the first recorded growth mark in older individuals of the same element. Integrating these data with the growth modeling results, we determined that the first size-frequency peak (late juveniles) corresponded with two year old individuals (Fig 3-3B, D). By this stage, the medullary cavity had already expanded beyond the circumference of the estimated yearling growth mark of ~100 mm (Fig. 3-11). In fact, the

RMDQ sample did not contain individuals smaller than about 40% of asymptotic adult body size for E. annectens (Fig. 3-12). Although smaller sized individuals can be subject to hydraulic sorting (Brown et al. 2013a, 2013b, 2013c), the results of the RMDQ autopodial element size- frequency distribution (Fig. 3-6) indicated that autopodial elements were present in excess and did not vary in their overall degree of completeness relative to long bones from the same population. This suggested that taphonomic biases had not contributed towards the absence of nestling-sized long bones in the RMDQ sample, which were hydraulically equivalent to late juvenile-adult autopodial elements, providing further evidence that segregation between nestling- juvenile and adult hadrosaurids may have been a real biological signal (Chapter 2).

Individuals from the second size-frequency peak (early subadults) recorded two growth marks in addition to the outer laminar layering and corresponded with three year old individuals. The third size-frequency peak (late subadults) had growth mark age ranges that overlapped between four and five year old individuals. By this stage, the degree of secondary remodeling, in particular the expansion of the medullary cavity and development of secondary osteons, had already obliterated the two year old growth mark in the samples of humeri and femora. This pattern continued in subsequent size-frequency peaks for both of these elements, whereas the tibiae recorded all of the preceding growth marks, except for the estimated yearling growth mark, in

181 each specimen regardless of ontogenetic stage indicating that tibiae provided the most consistently complete growth record (Fig. 3-11). The fourth size-frequency peak (early adults) consisted of individuals five to seven years of age, and the final fifth size-frequency peak consisted of late adults six years of age and older, with one individual approaching 20 years

(ROM 73853). Although the three most mature individuals from the sample fell within the late adult size class, the inclusive adult size class of RMDQ demonstrates that there was a certain degree of variation in the growth and asymptotic body size within a single E. annectens population. Therefore, the use of size-frequency peaks, or size-classes, from size-frequency distributions can only be used as a proxy for age in early ontogeny and requires the integration of osteohistological data to accurately identify the precise ontogenetic age of each size class.

The body mass growth curve analysis of the RMDQ E. annectens sample indicated that the average asymptotic body mass was ~5595 kg, whereas the maximum was ~6075 kg and was calculated using the minimum diaphyseal circumferences from the largest RMDQ humerus and femur and the well-established interspecific body mass equation for quadrupedal vertebrates

(Campione and Evans 2012). When comparing the maximum RMDQ body mass with estimated body masses of associated skeletons of Edmontosaurus (Table 3-2), RMDQ ranked among the highest and just under AMNH 5730 (~6603 kg) and CCM V 1938.8 (~6922 kg). The late juvenile LACM 23504 was estimated to be ~579 kg based on DME (Erickson and Tumanova

2000), and because it consistently placed within the late juvenile size class of RMDQ (Figs. 3-5), it provided a lower bound estimate for the RMDQ population and an approximate body mass for individuals approaching two years of age. Interestingly, the holotype of E. annectens, USNM

2414 (Marsh 1892), placed within the early adult size class (Fig. 3-3A) and had an estimated body mass of ~3351 kg, suggesting that it had not yet attained skeletal maturity; this is discussed below in further detail. When compared with other hadrosaurids, the average asymptotic body

182 mass of ~5595 kg was ~257 kg above the largest individual from the Dinosaur Park Formation

(TMP 1979.014.0020, 5338 kg) and approximately 1250-1600 kg larger than hadrosaurids from the penecontemporaneous Two Medicine Formation of Montana (Probrachylophosaurus,

Maiasaura, and Hypacrosaurus) (Chapter 2). Despite these differences, E. annectens had attained 95% of its asymptotic body mass by about nine years of age, which is similar to estimates of nine years for Maiasaura and Probrachylophosaurus and seven years for individuals from the DPF (Chapter 2). Given this, we hypothesize that hadrosaurids inherited a similar growth strategy attaining asymptotic body size between seven to nine years of age.

3.6.1 Population Dynamics of Edmontosaurus

Hadrosaurid dinosaurs have been historically defined as being gregarious based on evidence of numerous bonebed accumulations (e.g. Christians 1992; Colson et al. 2004; Horner et al. 2004;

Lauters et al. 2008; Scherzer and Varrichio 2010; Bell and Campione 2014; Eberth et al. 2014;

Hone et al. 2014; Evans et al. 2015, Woodward et al. 2015, Ullman et al. 2017; Bell et al. 2018).

However, before discussing the population dynamics of an extinct animal, we need to definitively identify the depositional origin of the sample assemblage, or manner of death. If an assemblage is attritional, or selective, it preserves the mortality rate of a hypothetical population over time, whereas a catastrophic, or non-selective, assemblage provides a snapshot of the standing crop as it existed at one time (Olson 1957; Voorhies 1969). Only a catastrophic assemblage will presumably provide data on the proportions of individuals and cohorts within a living population, but in most cases, a bonebed will become secondarily altered (e.g. winnowing, scavenging, disarticulation, overprinting) making it more difficult to identify the depositional origin (Rogers and Kidwell 2007) and may subsequently influence interpretations related to

183 population structure. Therefore, it is important to present data beyond geological and taphonomic information to determine the accurate depositional nature of the assemblage.

Based on data from previous geological and taphonomic studies of the RMDQ (Christians 1991,

1992), this E. annectens bonebed has been defined as a catastrophic assemblage that was secondarily deposited locally. Our data provide further evidence on the manner of death of this assemblage. When size-frequency distributions from individual elements were consolidated into a combined size-frequency distribution, size-frequency peaks aligned not only between different elements, but also with the osteohistologically determined ages suggesting that cohorts constituted the size-frequency peaks. The proportions of these cohorts reflected the general distributions of catastrophic assemblages in that each subsequent cohort consisted of fewer individuals than the previous cohort, resulting in a ‘step-wise’ reduction towards senescent adults

(Olson 1957). The natural sheen of the external morphology and minimal signs of abrasion supported previous conclusions that any secondary transport was local. The entire sample of osteohistologically sectioned individuals preserved a similar layering of laminar oriented vascular canals suggesting that the mass death event was tied to a single season that correlated with the slow-growing period. This collective combination of morphological, osteohistological, geological, and taphonomic data for RMDQ provides the first substantial evidence of a catastrophic bonebed of a monodominant hadrosaurid population.

Using the size-frequency profiles of RMDQ, we can better understand the population dynamics of E. annectens. Because of its catastrophic nature, cohorts were presumably preserved proportionately to the standing crop of the living population. Given this, we can confidently infer that E. annectens individuals congregated into large herds for a portion of the year that corresponded with the slow-growing season. The composition of herds ranged from two year old

184 late juveniles to mature adults of at least 18 years of age (ROM 73853) suggesting that senescent individuals likely remained within the herd until death. When compared with other

Edmontosaurus bonebeds (Fig. 3-12), the absence of nestling-yearling size individuals further supports the hypothesis of segregation from older cohorts (Chapter 2). This is particularly evidenced by the size profile of the Liscomb Bonebed form the Prince Creek Formation of the

North Slope of Alaska (Gangloff and Fiorillo 2010). With the exception of a partially preserved and potentially misidentified adult tibia, the Liscomb Bonebed consists of yearling to two year old individuals that would bridge the gap between nestlings (Wosik et al. 2017b; Wosik et al.

2018) and the RMDQ population. If these estimated ages are accurate, this suggests that late- nestling to juvenile individuals formed their own potentially independent groups and these individuals reintegrated with the main herd between two to three years of age.

3.6.2 Reevaluating the Effects of Environmental Stressors on

Osteohistology in Edmontosaurus

Previous comparative osteohistological analyses of polar and temperate populations of

Edmontosaurus from the Maastrichtian (Late Cretaceous) of North America have suggested that polar population overwintered in their resident polar paleoenvironment rather than migrating to less harsh environmental regions (Chinsamy et al. 2012). Long bones of Edmontosaurus sp. from the Prince Creek Formation of Alaska (Gangloff and Fiorillo 2010), which were derived from small individuals under two years of age, showed textural shifts between reticular and laminar

(circumferential) fibrolamellar bone vascularization (Chinsamy et al. 2012). Conversely, long bones from a sample of larger E. regalis from the Horseshoe Canyon Formation of southern

Alberta contained individuals that inconsistently exhibited these textural switches (Chinsamy et al. 2012). The authors suggested that textural shifts resulted from environmental stressors and

185 not migratory behavior and proposed that all individuals in the polar population showed textural shifts because they were subjected to very strong environmental stressors in the form of harsh winters (Chinsamy et al. 2012), when not only temperature but changes in forage quality and availability would be detrimental to growth and survival. Only some individuals in the temperate population showed textural shifts because the environment was interpreted to have been more stable with only occasional decreases in winter forage quality that did not uniformly affect each individual (see also Vanderven et al. 2014). Therefore, variability in bone histology within and between Edmontosaurus populations reflected the intensity of environmental stressors, not movement away from such stressors. Although this is an interesting hypothesis, evaluating it is confounded by the differently sized individuals, of potentially different ontogenetic stages, that were sampled from the polar (juvenile) and temperate (subadult-adult) populations (Fig. 3-13C).

The latitudinal differences of multiple congeneric Edmontosaurus bonebeds (Fig. 3-13A) provide a rare study sample to investigate whether these osteohistological differences are indeed related to environmental stressors, or due to the sampling of differently sized individuals of potentially different ontogenetic stages (Nelms 1989; Fiorillo and Gangloff 2001; Campione and

Evans 2011). Considering the size ranges of each population (Fig. 3-13C), the polar population consisted primarily of juveniles, with a maximum body size of ~51% of the largest corresponding element from RMDQ that were still undergoing rapid growth of primary bone tissues subject to little, if any, secondary osteon development. The RMDQ and temperate populations had similar size ranges that included late juveniles through late adults. The largest individuals in the RMDQ sample (ROM 67794, ROM 73853) exhibited heavy secondary osteon development, which obscured large portions of their growth records. When reviewing the material from the temperate population, femora UALVP 52731 and 47920 (Chinsamy et al.

2012: figure 3a, b) were greater than 1150 mm in total length and preserved only one or lacked

186 any cycles, respectively, of reticular-circumferential oriented fibrolamellar bone because they exhibited heavy secondary osteon development that had obliterated the primary bone tissue and the original growth record, characteristics indicative of late adults. The third example, UALVP

52696 (Chinsamy et al. 2012: figure 3c) recorded three zonal shifts because it was a subadult and was still undergoing extensive growth. Therefore, rather than distinguishing between migration and overwintering, our study indicates that the putative differences between the temperate and polar populations may reflect the growth stages of individuals in each sample. Further studies should explicitly focus on comparing overlapping material over a range of size and age classes to test for latitudinal differences in dinosaurian growth strategies. It is also important to note that the large tibia from the polar population (DMNH 22557; Chinsamy et al. 2012: figure 2a), which recorded about eight growth cycles, may have been misidentified based on its partial preservation and because it was not part of the Liscomb Bonebed assemblage. If this single specimen is removed from the polar population dataset, then the size distribution of this assemblage does not exceed 50% that of the largest RMDQ individuals and lacks substantial overlap to make any comparisons. In addition, more recent studies on modern large bodied herbivores (Köhler et al. 2012; Mumby et al. 2015) have revealed that internal physiology drives seasonal growth cycles within the bone microstructure suggesting that external environmental stressors may only have a secondary and indirect influence.

3.6.3 Histologically Assessing the Validity of Anatotitan

Anatotitan, a large bodied hadrosaurid, was originally described as a distinct species based primarily on the long, low shape of its skull and other subtle cranial morphologies (Lull and

Wright 1942; Brett-Surman 1979; Chapman and Brett-Surman 1990). Horner et al. (2004) and

Prieto-Márquez (2010) argued that this unusual shape was caused, in part, by taphonomic

187 crushing of the skull in the dorso-ventral axis and synonymized Anatotitan as a large

Edmontosaurus annectens. Campione and Evans (2011) investigated this synonymization by performing linear and geometric morphometric analyses of the cranium for five putative hadrosaurid species. Their analyses refuted the hypothesis that Anatotitan was a distinct species, placing it instead as an ontogenetic endpoint for E. annectens, and their independently supported the hypothesis of dorso-ventral flattening due to taphonomic influences. In our study we further tested the hypothesis that Anatotitan is, in reality, a mature E. annectens by histologically sectioning the right humerus of CCM V 1938.8 at its minimum diaphyseal circumference. This type of approach has proven useful in a similar regard and has helped resolve taxonomic disputes in other dinosaurian taxa such as Triceratops (Scannella and Horner 2010) and

Pachycephalosaurus (Horner and Goodwin 2009).

The external morphology of the humerus exhibited a fairly worn periosteal surface, substantially developed muscle scars, and extensively interweaved attachment areas for cartilaginous caps at both ends of the bone suggesting it was an older individual. The internal bone microstructure further indicated the individual was mature through a combination of features (Fig. 3-14). The inner cortex was composed of dense Haversian bone (Reid 1985) with multigenerational overlap of secondary osteons completely obliterating the primary bone, similar to the largest humerus section from RMDQ (ROM 67794). Much of the scattered erosional cavities had developed into secondary osteons with multiple cement lines, which continued into the outer cortex and were occasionally present just below the periosteal surface. About six zones of sublaminar-laminar oriented parallel-fibered/lamellar bone were encapsulated by LAGs, two of which were potentially double and triple LAGs. This was followed by a closely stacked layering of at least three LAGs near the periosteal surface, which may have been the initiation of an external fundamental system (Horner et al. 2000) or outer circumferential layer (Chinsamy-Turan 2005)

188 indicating the onset of skeletal maturity. Retrocalculation revealed that the first recorded growth mark corresponded with ~3.5 years of age, mirroring the results of humeri from the RMDQ sample. Growth modeling indicated that 95% asymptotic body size had already been attained and was done so within nine years of age, identical to E. annectens from the RMDQ. When superimposing the total femur lengths of associated skeletons referred to Anatotitan onto the combined size-frequency distribution of RMDQ (Fig. 3-3A), both CCM V 1938.8 and AMNH

5730 placed within late adult size class. In fact, E. annectens individuals from RMDQ attained larger sizes than the referred Anatotitan specimens, suggesting that these two individuals fell within the spread of data available for E. annectens bonebeds (Fig. 3-12).

An alternative hypothesis could be that the subtle cranial differences of Anatotitan instead represented sexual differences and/or the end stage of cranial development of E. annectens.

Interestingly, the holotype of E. annectens, USNM 2414, placed within the early adult size class of the combined RMDQ size-frequency distribution (Fig. 3-3A), indicating that it had not yet attained skeletal maturity, and should not be considered a fully mature adult based solely on size unless osteohistologically examined to demonstrate otherwise. Therefore, the end stage of cranial development of E. annectens may not be represented by the holotype, USNM 2414, suggesting that the proposed subtle cranial differences, if not due to taphonomic crushing, in Anatotitan specimens may instead represent the ontogenetic endpoint of E. annectens. However, when assessing similarly sized cranial elements from the RMDQ for the putatively autapomorphic cranial morphologies of Anatotitan (Lull and Wright 1942; Brett-Surman 1979; Chapman and

Brett-Surman 1990), such as the more pronounced anteriorly directed bowing of the quadrate, the ontogenetic sequence of E. annectens available from the RMDQ did not exhibit such changes. Therefore, we suggest that these two specimens, which fell within the variation of adult

189

E. annectens individuals, were likely a result of diagenetic deformation, a process that is not uncommon in fossil specimens.

3.7 Conclusion

When the size-frequency and osteohistological datasets were combined, growth marks aligned with size-frequency peaks, with the exclusion of the overlapping subadult-adult size range, indicating a strong size-age relationship in early ontogeny. A growth curve analysis of the tibia indicated that E. annectens exhibited a similar growth trajectory to other hadrosaurids suggesting that the clade as a whole may have inherited a similar growth strategy. Individuals smaller than

40%, were not present in this catastrophic assemblage providing further support that juvenile hadrosaurids segregated from adults. Osteohistological comparison with material from polar and temperate populations of Edmontosaurus revealed that previous conclusions correlating osteohistological growth patterns with the strength of environmental stressors were a result of sampling non-overlapping ontogenetic growth stages. The osteohistological assessment of

Anatotitan revealed the sampled individual had attained the threshold for skeletal maturity, and when compared with the RMDQ population, it fell within the variation of growth for late adults of E. annectens.

3.8 Acknowledgments

Access to specimens was facilitated by P. Larson and B. Ferrar (BHIGR), N. Carroll (CCM), C.

Boyd, J. Persons, and B. Barnes (NDGS), K. Seymour and B. Iwama (ROM), W. Ripley and D.

190

Evans (TCM), and C. Eaton and D. Lovelace (UWGM). Funding for this project was generously provided by a Dinosaur Research Institute Student Project Grant (to MW), a Joseph Bazylewicz

Fellowship (to MW), a University of Toronto Fellowship (to MW), and a National Sciences and

Engineering Research Council Discovery Grant (to DCE). Life reconstructions and silhouettes were prepared by D. Dufault (ROM). Preparation of specimens was assisted by S. Sugimoto

(ROM), I. MacDonald (TMP), I. Morrison (ROM), and L. Yeider. Wiresaw access for cutting of large specimens was granted by K. Tait (ROM) and facilitated by I. Nicklin (ROM). Discussions with C. Brown, K. Chiba, D. McLennan, R. Reisz, M. Ryan, M. Silcox, D. Tanke, C. Woodruff, and H. Woodward greatly enhanced this manuscript.

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3.9 Tables

Table 3-1. List of Edmontosaurus specimens osteohistologically sampled and examined for this study and their corresponding measurement values. % RMDQ represents the ratio of the specimen to the largest corresponding element from RMDQ. Abbreviations: GM, growth mark;

MaxA, major axis diameter; MCmax, medullary cavity diameter along the major axis; MCmin, medullary cavity diameter along the minor axis; MC%, ratio between the cross-sectional areas of the medullary cavity and outer circumference, MinA, minor axis diameter.

191 192

Element Specimen Size-class Total Length % RMDQ Circumference % RMDQ MinA MaxA MCmin MCmax MC% Preserved GM Circs ROM 73849 late juvenile 375 54.5% 136 51.5% 32.3 47.8 18.5 31.3 37.5% ROM 67796 early subadult 452* 70.0% 173 65.5% 52.0 59.0 34.0 41.0 45.4% 143, 167 ROM 73850 late subadult 520 76.0% 208 78.5% 54.0 72.0 27.0 50.0 34.7% 144, 173, 186 Humerus 179, 196, 216, 227, 237, ROM 67794 late adult 650 95.0% 240 90.5% 69.0 85.0 40.0 54.0 36.8% 239, 241, 242, 243, 244, 245 CCM V 218, 243, 258, 266, 272, late adult 650 95.0% 280 105.5% 68.5 102.5 31.0 68.0 30.0% 1938.8 276, 279 ROM 67602 late juvenile 675 55.0% 255 53.5% 67.0 87.5 41.0 48.0 33.6% ROM 67798 late juvenile 704.5* 57.0% 256 54.0% 74.0 84.0 42.0 49.0 33.1% 227 Femur ROM 67799 early subadult 865 70.5% 318 67.0% 98.0 104.0 76.0 79.0 58.9% 272, 297 ROM 67792 early adult 1065 86.5% 410 86.5% 98.0 104.0 72.0 96.0 67.8% 330, 367.5, 385 ROM 67603 late juvenile 555 53.5% 184.5 51.5% 57.0 58.0 30.0 30.0 27.2% ROM 67601 late juvenile 575 55.5% 194 54.0% 54.0 61.0 25.0 32.0 24.3% ROM 67797 early subadult 677* 65.0% 233 65.0% 65.0 79.0 29.0 49.0 27.7% 196.5 ROM 67795 early subadult 720 69.0% 237.5 66.0% 72.0 73.0 33.0 37.0 23.2% 202 ROM 67793 early adult 875 84.0% 275 76.5% 80.0 85.0 38.0 42.0 23.5% 213, 249 Tibia 197, 236.5, 259.5, 274.5, ROM 73852 late adult 1030 99.0% 350 97.0% 104.0 115.5 47.5 52.0 20.6% 302, 318, 326.5, 332, 335, 336, 336.5, 337.5

212.5, 254.5, 282, 309.5, 329, 334.5, 338.5, 340.5, ROM 73853 late adult 1025 98.5% 355 100.0% 106.0 116.5 56.0 56.0 25.4% 342.75, 344, 345, 347, 349, 350, 351.5, 352.2, 353, 354

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Table 3-2. Summary of Edmontosaurus body mass estimates of associated skeletons (Wosik et al. 2017b) using the intraspecific equation for quadrupedal vertebrates (Campione and Evans

2012) and Development Mass Extrapolation (DME; Erickson and Tumanova 2000) using SM

R4050 as a presumably adult-sized E. annectens individual. % Difference is a ratio between the two methods; note juvenile and subadult specimens exhibit the largest discrepancies.

Abbreviations: HC+FC, sum of humerus and femur minimum diaphyseal circumferences.

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Specimen # Taxon Femur Length % RMDQ HC+FC Body Mass (kg) DME (HC+FC) % Difference

RMDQ max E. annectens 1233 100.0% 740 6075 6102 0.44%

AMNH 5730 E. annectens 1147.7 93.1% 762.8 6603 6684 1.21%

CCM V 1938.8 E. annectens 1152 93.4% 776 6922 7037 1.63%

CMNH 10178 E. annectens 910 73.8% 521 2315 2130 8.71%

FPDM E. annectens 990 80.3% 516.5 2261 2075 8.97%

LACM 23504 E. annectens 559 45.3% 337.5 702 579 21.27%

MOR 2939 E. annectens 1175 95.3% 782 7070 7201 1.82%

SDSM 4917 E. annectens 1032 83.7% 617 3685 3537 4.19%

SM R4050 E. annectens - - 727 5786 5786 0.00%

UCMP 137278 E. annectens 995 80.7% 621 3752 3606 4.04%

USNM 2414 E. annectens 1025 83.1% 606 3508 3351 4.68%

YPM 2182 E. annectens 1025 83.1% 735 5962 5979 0.29%

CMN 2289 E. regalis 1242.5 100.8% 802 7578 7768 2.44%

CMN 8399 E. regalis 1140 92.5% 609 3556 3401 4.55%

ROM 801 (5167) E. regalis 1280 103.8% 771 6800 6901 1.47%

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3.10 Figures and Figure Captions

Figure 3-1. Geographic maps of the United States (A) and South Dakota (B) denoting the location of the Ruth Mason Dinosaur Quarry (RMDQ).

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Figure 3-2. Examples of retrodeformation of RMDQ transverse cross-sections. A, B, femur

(ROM 67798). C, D, tibia (ROM 67603). A, C, unaltered. B, D, retrodeformed.

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Figure 3-3. Combined size-frequency distributions comprised of humeri, femora, and tibiae from

RMDQ. Tick marks below each size-frequency distribution correspond with individual bones. A, total length with overlaid femur lengths from several associated skeletons of E. annectens

(Wosik et al. 2017b). B, total length integrated with osteohistological data. C, minimum diaphyseal circumference. D, minimum diaphyseal circumference integrated with osteohistological data. N = 388. Estimated values based on an Ordinary Least Squares (OLS) regression between total length and minimum diaphyseal circumference (Supplementary Table

S3-1).

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Figure 3-4. Total length size-frequency distributions of individual long bone elements from the

Ruth Mason Dinosaur Quarry (RMDQ). Tick marks below each size-frequency distribution correspond with individual bones. Estimated values based on an Ordinary Least Squares (OLS) regression between total length and minimum diaphyseal circumference (Supplementary Table

S3-1).

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Figure 3-5. Minimum diaphyseal circumference size-frequency distributions of individual long bone elements from the Ruth Mason Dinosaur Quarry (RMDQ). Tick marks below each size- frequency distribution correspond with individual bones. A, B, humerus (n = 103). C, D, femur

(n = 155). E, F, tibia (n = 130). A, C, E, minimum diaphyseal circumference with overlaid minimum diaphyseal circumferences from several associated skeletons of E. annectens (Wosik et al. 2017b). B, D, E, minimum diaphyseal circumference data integrated with osteohistological data. Estimated values based on an Ordinary Least Squares (OLS) regression between total length and minimum diaphyseal circumference (Supplementary Table S3-1).

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Figure 3-6. Combined total length size-frequency distribution of metacarpals and metatarsals from the Ruth Mason Dinosaur Quarry (RMDQ). Tick marks below each size-frequency distribution correspond with individual bones. Measurements for E. annectens metatarsal III and nestling femur length were obtained from Wosik et al. (2017b), whereas those for Maiasaura nestlings originated from Horner et al. (2000). N = 270.

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Figure 3-7. Osteohistology of humeri from the Ruth Mason Dinosaur Quarry (RMDQ) under plain-polarized (PP) and cross-polarized (XP) light microscopy. Scale bars are 0.5 cm.

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Figure 3-8. Osteohistology of femora from the Ruth Mason Dinosaur Quarry (RMDQ) under plain-polarized (PP) and cross-polarized (XP) light microscopy. Scale bars are 0.5 cm.

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Figure 3-9. Osteohistology of tibiae from the Ruth Mason Dinosaur Quarry (RMDQ) under plain-polarized (PP) and cross-polarized (XP) light microscopy. Scale bars are 0.5 cm.

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Figure 3-10. Edmontosaurus annectens growth curves compared with Maiasaura peeblesorum and Probrachylophosaurus bergei. A, Tibial minimum diaphyseal circumference growth. B,

Body mass growth.

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Figure 3-11. Summary of section stacking of tibiae. Schematics highlight cortical bone (solid grey), extent of medullary cavity and/or secondary osteon development (dotted white), and growth marks (solid black line). Circumferences refer to extent of medullary cavity and/or secondary osteon development (MC/SR), earliest recorded growth mark (GM 1), and outer/periosteal circumference (Outer).

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Figure 3-12. Density comparison of long bone and tracksite size distributions of hadrosaurid bonebeds. N refers to sample size. Data for temperate and polar populations was derived from published literature: 1Wosik et al. 2017a; 2Evans et al. 2015a; 3Fiorillo et al. 2014; 4Woodward et al. 2015; 5Bell et al. 2018; 6Hone et al. 2014; 7Varricchio and Horner 1993; 8Scherzer and

Varricchio 2010; 9Lauters et al. 2008.

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Figure 3-13. A, Polar and temperate localities of Edmontosaurus (modified from Chinsamy et al.

2012). B, Biostratigraphy of Edmontosaurus (modified from Campione and Evans 2011). C,

Schematic of zonal-azonal bone across ontogenetic stages. Data for polar and temperate derived from Chinsamy et al. 2012.

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Figure 3-14. Osteohistology of the right humerus of Anatotitan (CCM V 1938.8) under plain- polarized (PP) and cross-polarized (XP) light microscopy. A, B, Full transverse cross-sections of the minimum diaphyseal circumference. C, Traced growth marks with extent of medullary cavity and/or heavy secondary osteon development outlined in dotted central region. D, E, Close-up of dotted boxed region.

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1 3.11 Supplementary Tables

10 Supplementary Table S3-1. Results from OLS regression analyses using complete elements

11 from RMDQ. Selected OLS regressions from Wosik et al. (2017a) using data from associated E.

12 annectens skeletons is listed for comparison.

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Limb Element (x) N R2 Slope (m) 95% CI m Intercept (b) 95% CI b p-value Trend

TL 31 0.94 0.995 0.90 1.09 -0.933 -1.53 -0.33 7.21E-19 iso Humerus C 31 0.94 0.941 0.85 1.03 1.265 0.79 1.74 7.21E-19 iso

TL 16 0.97 1.091 0.98 1.21 -1.602 -2.38 -0.82 8.47E-12 iso Femur C 16 0.97 0.887 0.79 0.98 1.641 1.10 2.18 8.47E-12 neg

TL 27 0.94 0.912 0.82 1.00 -0.487 -1.09 0.12 3.70E-17 iso Tibia C 27 0.94 1.035 0.93 1.14 0.874 0.30 1.45 3.70E-17 iso

Based on E. annectens associated data from Wosik et al. 2017a

Tibia Circ HC+FC 9 0.93 0.977 0.75 1.21 0.783 -0.54 2.11 2.12E-05 iso

HumC TibC 10 0.97 1.032 0.88 1.12 -0.574 -1.46 0.32 3.18E-07 iso

FemC TibC 10 0.87 0.959 0.66 1.26 0.462 -1.25 2.17 7.50E-05 iso

HumC+FemC TibC 9 0.93 0.956 0.73 1.18 -0.375 -1.82 1.07 2.12E-05 iso

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13 Supplementary Table S3-2. Parameter values for each age retrocalculation growth model along

14 with AICc scores, estimated values for age of first record growth mark (Est GM 1 Age) were

15 done for a hatchling tibia circumference of 25 mm and 35 mm.

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Specimen # Model AIC AICc dAICc AIC weight m A K I Est GM 1 Age (25 mm) Est GM 1 Age (35 mm)

Monomolecular 62.78 64.49 2.90 0.07 0 347.55 0.29 1.91 2.65 von Bertalanffy 61.41 63.13 1.54 0.13 2/3 344.75 0.34 1.00 3.67 Gompertz 60.89 62.61 1.01 0.17 0.999 343.64 0.36 0.63 4.28 ROM 73852 Logistic 59.88 61.59 0.00 0.28 2 340.92 0.43 -0.28 6.56 Extreme 59.95 61.66 0.07 0.27 4 337.75 0.59 -1.48 10.91 Innominate 62.47 64.18 2.59 0.08 8.4 335.19 0.93 -2.88 16.54 Averaged 59.90 61.61 - 1.00 2.56 341.02 0.48 -0.34 8.19 Monomolecular 85.35 86.27 5.61 0.03 0 351.98 0.38 1.47 2.27 von Bertalanffy 82.16 83.08 2.42 0.15 2/3 351.03 0.42 0.82 3.15 Gompertz 81.05 81.97 1.31 0.26 0.999 350.63 0.45 0.55 3.69 ROM 73853 Logistic 79.74 80.66 0.00 0.50 2 349.60 0.53 -0.28 5.59 Extreme 83.71 84.64 3.97 0.07 4 348.26 0.69 -1.16 9.64 Innominate 93.99 94.92 14.25 0.00 8.4 346.96 1.09 -2.36 14.72 Averaged 80.25 81.18 - 1.00 1.62 350.06 0.50 0.09 4.71 Monomolecular 203.50 203.98 0.28 0.23 0 351.78 0.31 1.81 2.58 2.48 von Bertalanffy 203.22 203.70 0.00 0.27 2/3 350.23 0.36 1.00 3.55 3.31 Gompertz 203.28 203.76 0.06 0.26 0.999 349.61 0.39 0.66 4.15 3.80 Combined 204.03 204.51 0.81 0.18 348.05 0.46 -0.20 6.34 5.55 (73852+73853) Logistic 2 Extreme 206.67 207.15 3.45 0.05 4 346.19 0.62 -1.36 10.54 8.92 Innominate 211.53 212.01 8.31 0.00 8.4 344.67 1.00 -2.71 15.78 13.28 Averaged 203.37 203.85 - 1.00 1.03 349.82 0.39 0.76 4.35 3.99 Monomolecular 243.33 243.75 0.00 0.99 0 341.98 0.50 -0.30 0.55 0.49 von Bertalanffy 253.88 254.31 10.55 0.01 2/3 339.29 0.64 -0.98 0.88 0.74 258.28 258.71 14.96 0.00 338.27 0.72 -1.23 1.08 0.89 Combined Gompertz 0.999 forced Logistic 268.79 269.21 25.46 0.00 2 335.98 0.98 -1.80 1.78 1.41 (100 mm GM1) Extreme 277.91 278.34 34.59 0.00 4 334.66 1.46 -2.44 3.14 2.45 Innominate 280.62 281.05 37.29 0.00 8.4 338.90 1.86 -3.55 6.75 5.41 Averaged 243.91 244.34 - 1.00 0.00 341.97 0.50 -0.30 0.55 0.48

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16 Supplementary Table S3-3. Parameter values for each body mass growth model along with

17 AICc scores. Retrocalculated ages used in these analyses corresponded with the 25 mm hatchling

18 tibial circumference.

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Dataset Model AIC AICc dAICc AIC weight m A K I Monomolecular 405.48 405.96 4.12 0.05 0 5842.40 0.21 -3.26 von Bertalanffy 401.38 401.86 0.02 0.42 2/3 5601.18 0.32 -5.01 Gompertz 401.36 401.84 0.00 0.42 0.999 5533.31 0.38 -5.53 Combined 404.33 404.81 2.98 0.10 5419.92 0.58 -6.57 (73852+73853) Logistic 2 Extreme 409.83 410.31 8.48 0.01 4 5356.32 0.95 -7.59 Innominate 416.02 416.50 14.67 0.00 8.4 5324.18 1.70 -8.56 Averaged 401.25 401.73 - 1.00 0.92 5566.49 0.37 -5.30 Monomolecular 446.38 446.81 0.64 0.36 0 5877.87 0.20 -0.41 von Bertalanffy 445.74 446.17 0.00 0.50 2/3 5444.40 0.40 -2.31 Gompertz 448.51 448.94 2.77 0.13 0.999 5389.14 0.48 -2.78 Combined forced 453.45 453.88 7.71 0.01 5383.10 0.63 -1.80 (100 mm GM1) Logistic 2 Extreme 464.47 464.89 18.73 0.00 4 5345.66 0.98 -4.88 Innominate 474.78 475.21 29.04 0.00 8.4 5315.96 1.77 -5.89 Averaged 443.53 443.96 - 1.00 0.48 5594.50 0.34 -1.67

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251

Appendices

Appendix 2-1. Total length and minimum diaphyseal circumference data of all specimens using

in Dinosaur Park Formation (DPF) analyses. Estimated values were based on the OLS

regressions (Supplementary Table 2-3). Percentage values were scaled to Corythosaurus

casuarius (ROM 845).

Specimen # Element Asso/Iso RawTL RawTL %Cory EstTL EstTL %Cory RawCirc RawCirc %Cory EstCirc EstCirc %Cory

AMNH 21521 Tibia I 925 92.69 92.69 324 93.88

AMNH 21521 Fibula I 890 93.59 93.59 131 77.74 77.74

AMNH 21522 Femur I 725 67.41 67.41 272 70.74 70.74

AMNH 21527 Humerus I 512 92.09 92.09 216 87.68

AMNH 30201 Femur I 990 92.05 92.05 415 107.93 107.93

AMNH 3839 Humerus A 466 83.82 195 79.11 79.11

AMNH 3839 Tibia A 960 96.19 96.19 338 97.70

AMNH 3839 Fibula A 995 104.63 104.63 185 109.79 109.79

AMNH 5240 Femur A 1080 100.42 100.42 414 107.56

AMNH 5240 Tibia A 1000 100.20 100.20 353 102.08

AMNH 5240 Fibula A 950 99.89 99.89 160 94.77

AMNH 5338 Humerus A 546 98.20 98.20 231 93.65

AMNH 5338 Radius A 577 87.89 87.89 139 92.41

AMNH 5338 Ulna A 609 85.47 85.47 156 88.90

AMNH 5338 Femur A 987 91.77 91.77 378 98.37

AMNH 5338 Tibia A 924 92.59 92.59 324 93.77

AMNH 5338 Fibula A 882 92.74 92.74 148 88.01

AMNH 5340 Humerus A 305 54.86 54.86 127 51.56

AMNH 5340 Radius A 320 48.74 48.74 80 52.92

AMNH 5340 Ulna A 350 49.12 49.12 89 50.73

251 252

AMNH 5340 Femur A 590 54.86 54.86 227 59.05

AMNH 5340 Tibia A 550 55.11 55.11 186 53.71

AMNH 5340 Fibula A 530 55.73 55.73 89 52.98

AMNH 5345 Humerus I 442 79.55 185 75.05 75.05

AMNH 5350 Humerus A 518 93.17 93.17 207 83.98 83.98

AMNH 5350 Femur A 1150 106.93 106.93 440 114.43 114.43

AMNH 5350 Tibia A 1005 100.70 100.70 354 102.46 102.46

AMNH 5350 Fibula A 945 99.37 99.37 167 99.11 99.11

AMNH 5436 Femur I 525 48.81 48.81 202 52.59

CMN 1070 Humerus I 393 70.68 70.68 145 58.82 58.82

CMN 2272 Ulna I 693 97.26 97.26 162 92.05 92.05

CMN 2278 Humerus A 620 111.52 260 105.48 105.48

CMN 2278 Femur A 1125 104.60 104.60 431 112.01

CMN 2278 Tibia A 1030 103.21 103.21 364 105.38

CMN 2278 Fibula A 980 103.05 103.05 165 97.75

CMN 32825 Ulna A 510 71.53 130 73.86 73.86

CMN 332b Tibia I 1081 108.32 108.32 380 109.99 109.99

CMN 34825 Humerus A 383 68.88 160 64.91 64.91

CMN 34825 Radius A 335 51.03 51.03 104 69.10 69.10

CMN 34825 Femur A 736 68.43 68.43 283 73.60 73.60

CMN 34825 Tibia A 703 70.39 70.39 234 67.73 67.73

CMN 34825 Fibula A 633 66.51 66.51 104 61.42 61.42

CMN 351 Fibula I 955 100.42 100.42 152 90.21 90.21

CMN 36141 Humerus I 357 64.21 64.21 147 59.63 59.63

CMN 419 Humerus A 692 124.46 124.46 255 103.45 103.45

CMN 419 Radius A 635 96.73 96.73 155 102.99 102.99

CMN 419 Ulna A 715 100.35 100.35 177 100.57 100.57

CMN 56331 Tibia I 775 77.66 77.66 253 73.23 73.23

CMN 56332 Tibia I 510 51.10 51.10 180 52.10 52.10

CMN 56333 Tibia I 415 41.58 41.58 150 43.42 43.42

253

CMN 8676 Humerus A 455 81.83 81.83 185 75.05 75.05

CMN 8676 Radius A 513 78.14 78.14 120 79.73 79.73

CMN 8676 Ulna A 562 78.88 78.88 145 82.39 82.39

CMN 8676 Femur A 890 82.75 82.75 341 88.78

CMN 8676 Tibia A 813 81.46 81.46 282 81.73

CMN 8676 Fibula A 775 81.49 81.49 130 77.37

CMN 8703 Humerus A 540 97.12 97.12 228 92.59

CMN 8703 Radius A 628 95.66 95.66 151 100.11

CMN 8703 Ulna A 658 92.35 92.35 169 96.14

CMN 8703 Femur A 1020 94.84 94.84 390 101.43 101.43

CMN 8703 Tibia A 1019 102.05 102.05 360 104.11

CMN 8703 Fibula A 940 98.84 98.84 145 86.05 86.05

CMN 8704 Radius A 620 94.44 94.44 124 82.39 82.39

CMN 8704 Ulna A 690 96.84 96.84 158 89.77 89.77

CMN 8784 Humerus A 266 47.91 111 45.03 45.03

CMN 8784 Femur A 515 47.88 47.88 198 51.60

CMN GFS 10-1916 Ulna I 487 68.35 68.35 125 71.02 71.02

CMN GFS 12-1916 Tibia I 465 46.59 46.59 171 49.49 49.49

CMN Lambe 381 Ulna I 385 54.04 54.04 103 58.52 58.52

CMN Lambe 673 Tibia I 530 53.11 53.11 185 53.55 53.55

MCSNM 345 Humerus A 730 131.29 131.29 311 126.12

MCSNM 345 Radius A 680 103.58 103.58 162 107.94

MCSNM 345 Ulna A 785 110.18 110.18 202 114.96

MCSNM 345 Femur A 1150 106.93 106.93 440 114.48

MCSNM 345 Tibia A 1080 108.22 108.22 383 110.88

ROM 1218 Humerus A 534 95.95 95.95 225 91.28 91.28

ROM 1218 Radius A 622 94.74 94.74 146 97.01 97.01

ROM 1218 Ulna A 691 96.98 96.98 162 92.05 92.05

ROM 1218 Femur A 1063 98.84 98.84 381 98.96 98.96

ROM 1218 Tibia A 958 95.94 95.94 329 95.22 95.22

254

ROM 1218 Fibula A 912 95.85 95.85 147 86.94 86.94

ROM 1423 Radius A 611 93.07 93.07 154 102.33 102.33

ROM 1423 Ulna A 646 90.67 90.67 173 98.30 98.30

ROM 1947 Humerus A 353 63.49 63.49 162 65.52 65.52

ROM 1947 Radius A 406 61.84 61.84 95 63.12 63.12

ROM 1947 Ulna A 439 61.61 61.61 113 64.20 64.20

ROM 1947 Fibula A 547 57.50 94 55.79 55.79

ROM 3508 Humerus I 216 38.76 38.76 103 41.78 41.78

ROM 44981 Fibula I 786 82.65 82.65 136 80.71 80.71

ROM 49695 Humerus I 550 98.92 98.92 238 96.55 96.55

ROM 49866 Femur I 128 11.94 11.94 46 11.96 11.96

ROM 58134 Tibia I 132 13.24 41 11.72 11.72

ROM 634 Tibia I 840 84.17 84.17 295 85.38 85.38

ROM 644 Radius I 502 76.47 76.47 118 78.41 78.41

ROM 655 Tibia I 1049 105.11 105.11 340 98.41 98.41

ROM 656 Femur I 1016 94.47 94.47 414 107.67 107.67

ROM 660 Tibia I 1065 106.71 106.71 345 99.86 99.86

ROM 669 Tibia I 1063 106.51 106.51 338 97.83 97.83

ROM 706 Femur I 137 12.76 12.76 54 14.04 14.04

ROM 764 Humerus A 609 109.44 109.44 242 98.17 98.17

ROM 764 Radius A 576 87.74 87.74 141 93.36 93.36

ROM 764 Ulna A 624 87.58 87.58 158 89.77 89.77

ROM 764 Femur A 1026 95.40 95.40 393 102.23

ROM 764 Tibia A 920 92.18 92.18 296 85.67 85.67

ROM 764 Fibula A 879 92.38 92.38 163 96.74 96.74

ROM 768 Humerus A 562 101.08 101.08 260 105.27 105.27

ROM 768 Radius A 506 77.00 77.00 160 106.31 106.31

ROM 768 Ulna A 576 80.77 80.77 188 106.53 106.53

ROM 768 Femur A 1065 99.02 99.02 410 106.63 106.63

ROM 777 Femur A 1055 98.09 98.09 385 100.13 100.13

255

ROM 787 Humerus A 531 95.41 95.41 218 88.44 88.44

ROM 787 Radius A 485 73.88 73.88 138 91.69 91.69

ROM 787 Ulna A 555 77.89 77.89 157 89.20 89.20

ROM 787 Femur A 1000 92.98 92.98 345 89.73 89.73

ROM 787 Tibia A 881 88.28 88.28 313 90.59 90.59

ROM 787 Fibula A 839 88.22 88.22 141 83.68 83.68

ROM 829 Radius I 571 86.98 86.98 120 79.73 79.73

ROM 845 Humerus A 556 100.00 100.00 247 100.00 100.00

ROM 845 Radius A 657 100.00 100.00 151 100.00 100.00

ROM 845 Ulna A 713 100.00 100.00 176 100.00 100.00

ROM 845 Femur A 1076 100.00 100.00 385 100.00 100.00

ROM 845 Tibia A 998 100.00 100.00 346 100.00 100.00

ROM 845 Fibula A 951 100.00 100.00 169 100.00 100.00

TMP 1965.010.0018 Tibia I 920 92.18 92.18 322 93.34

TMP 1965.010.0021 Fibula I 909 95.55 151 89.61 89.61

TMP 1966.004.0001 Humerus A 505 90.83 90.83 213 86.45

TMP 1966.004.0001 Radius A 630 95.96 95.96 151 100.42

TMP 1966.004.0001 Ulna A 675 94.74 94.74 174 98.66

TMP 1966.004.0001 Femur A 1060 98.56 98.56 406 105.59

TMP 1966.004.0001 Tibia A 1015 101.70 101.70 358 103.73

TMP 1966.004.0001 Fibula A 970 102.00 102.00 163 96.76

TMP 1966.017.0026 Radius I 451 68.66 111 73.75 73.75

TMP 1966.031.0058 Fibula I 819 86.09 137 81.31 81.31

TMP 1966.031.0085 Tibia A 790 79.16 79.16 266 76.99 76.99

TMP 1966.031.0085 Fibula A 790 83.07 83.07 136 80.71 80.71

TMP 1967.008.0063 Tibia I 380 38.08 38.08 125 36.10

TMP 1967.008.0070 Fibula I 875 92.01 92.01 143 84.87 84.87

TMP 1967.010.0079 Ulna I 462 64.84 64.84 109 61.93 61.93

TMP 1967.010.0082 Tibia I 405 40.58 40.58 140 40.52 40.52

TMP 1967.015.0021 Radius I 552 84.08 84.08 123 81.73 81.73

256

TMP 1967.018.0011 Humerus I 670 120.50 120.50 253 102.64 102.64

TMP 1967.020.0239 Tibia I 190 19.04 19.04 75 21.71 21.71

TMP 1979.014.0020 Tibia I 1100 110.22 110.22 400 115.77 115.77

TMP 1979.014.0297 Tibia I 900 90.18 90.18 308 89.15 89.15

TMP 1979.014.0298 Femur I 668 62.11 62.11 308 80.10 80.10

TMP 1979.014.0308 Tibia I 465 46.59 46.59 175 50.51 50.51

TMP 1979.014.0487 Femur I 532 49.47 49.47 194 50.46 50.46

TMP 1979.014.0488 Femur I 860 79.96 79.96 355 92.33 92.33

TMP 1979.014.0760 Fibula I 665 69.93 69.93 115 68.25 68.25

TMP 1980.008.0095 Radius I 283 43.10 76 50.50 50.50

TMP 1980.016.0818 Tibia I 118 11.86 36 10.42 10.42

TMP 1980.016.0957 Tibia I 146 14.62 45 13.02 13.02

TMP 1980.016.1671 Femur I 1205 112.04 112.04 461 119.91

TMP 1980.022.0001 Humerus A 553 99.37 99.37 234 94.79

TMP 1980.022.0001 Radius A 502 76.47 76.47 122 81.01

TMP 1980.022.0001 Ulna A 520 72.98 72.98 133 75.75

TMP 1980.022.0001 Femur A 955 88.80 88.80 366 95.21

TMP 1980.022.0001 Tibia A 860 86.17 86.17 300 86.81

TMP 1980.022.0001 Fibula A 815 85.70 85.70 137 81.35

TMP 1980.022.0003 Femur I 805 74.87 307 79.84 79.84

TMP 1980.023.0004 Humerus A 546 98.20 98.20 231 93.65

TMP 1980.023.0004 Radius A 616 93.83 93.83 148 98.30

TMP 1980.023.0004 Ulna A 671 94.18 94.18 173 98.07

TMP 1980.023.0004 Femur A 1145 106.46 106.46 438 113.99

TMP 1980.023.0004 Tibia A 996 99.80 99.80 351 101.65

TMP 1980.029.0101 Humerus A 487 87.50 87.50 251 101.62 101.62

TMP 1980.029.0101 Ulna A 547 76.77 76.77 182 103.41 103.41

TMP 1980.030.0048 Fibula I 411 43.22 72 42.73 42.73

TMP 1980.040.0001 Humerus A 580 104.32 104.32 235 95.33 95.33

TMP 1980.040.0001 Radius A 615 93.68 93.68 148 98.15

257

TMP 1980.040.0001 Radius A 629 95.81 95.81 148 98.34 98.34

TMP 1980.040.0001 Ulna A 645 90.53 90.53 166 94.22

TMP 1980.040.0001 Femur A 1070 99.49 99.49 410 106.58

TMP 1980.040.0001 Tibia A 950 95.19 95.19 334 96.61

TMP 1980.040.0001 Fibula A 905 95.16 95.16 152 90.30

TMP 1981.014.0035 Tibia I 714 71.59 245 70.91 70.91

TMP 1981.016.0373 Ulna I 107 15.02 15.02 30 17.05 17.05

TMP 1981.016.0375 Femur I 119 11.10 47 12.22 12.22

TMP 1981.018.0234 Ulna I 658 92.32 167 94.89 94.89

TMP 1981.019.0076 Fibula I 735 77.29 77.29 146 86.65 86.65

TMP 1981.019.0077 Humerus I 568 102.16 102.16 238 96.55 96.55

TMP 1981.019.0126 Tibia I 930 93.19 93.19 326 94.43

TMP 1981.019.0128 Tibia I 390 39.08 39.08 137 39.65 39.65

TMP 1981.029.0002 Radius I 458 69.76 69.76 104 69.10 69.10

TMP 1981.037.0001 Tibia I 510 51.10 171 49.49 49.49

TMP 1982.016.0054 Humerus I 525 94.42 94.42 221 89.66 89.66

TMP 1982.016.0085 Humerus I 272 48.92 48.92 117 47.46 47.46

TMP 1982.016.0283 Humerus I 304 54.68 54.68 137 55.58 55.58

TMP 1982.019.0300 Tibia I 1010 101.20 101.20 350 101.30 101.30

TMP 1982.037.0001 Femur A 892 82.94 82.94 314 81.66 81.66

TMP 1982.037.0001 Tibia A 868 86.92 86.92 303 87.63

TMP 1982.037.0001 Fibula A 775 81.49 81.49 109 64.69 64.69

TMP 1982.038.0001 Radius A 665 101.29 101.29 145 96.35 96.35

TMP 1982.038.0001 Ulna A 685 96.14 96.14 145 82.39 82.39

TMP 1982.038.0001 Femur A 1140 106.00 106.00 405 105.20 105.20

TMP 1982.038.0001 Tibia A 1073 107.46 107.46 361 104.49 104.49

TMP 1982.038.0001 Fibula A 995 104.63 104.63 138 81.60 81.60

TMP 1984.001.0001 Humerus A 560 100.72 100.72 237 96.11

TMP 1984.001.0001 Radius A 540 82.25 82.25 131 86.79

TMP 1984.001.0001 Ulna A 584 81.96 81.96 150 85.20

258

TMP 1984.001.0001 Femur A 1045 97.16 97.16 400 104.11

TMP 1984.001.0001 Tibia A 895 89.68 89.68 313 90.62

TMP 1984.001.0001 Fibula A 900 94.64 94.64 151 89.80

TMP 1984.036.0012 Fibula I 815 85.70 85.70 137 81.35

TMP 1984.067.0002 Ulna I 280 39.30 39.30 88 50.00 50.00

TMP 1984.067.0060 Tibia I 108 10.82 10.82 33 9.55 9.55

TMP 1984.121.0001 Humerus A 530 95.32 95.32 224 90.84

TMP 1984.121.0001 Radius A 640 97.49 97.49 153 101.92

TMP 1984.121.0001 Ulna A 650 91.23 91.23 167 94.96

TMP 1984.121.0001 Femur A 1040 96.70 96.70 398 103.61

TMP 1984.121.0001 Tibia A 980 98.20 98.20 345 99.89

TMP 1984.163.0026 Humerus I 118 21.28 49 19.88 19.88

TMP 1985.036.0048 Humerus I 580 104.32 104.32 246 99.63

TMP 1985.036.0138 Tibia I 117 11.72 11.72 35 10.13 10.13

TMP 1985.036.0164 Humerus I 73 13.08 30 12.17 12.17

TMP 1985.056.0117 Fibula I 928 97.58 97.58 147 87.24 87.24

TMP 1985.059.0055 Humerus I 73 13.08 30 12.17 12.17

TMP 1986.049.0011 Humerus I 70 12.59 12.59 24 9.74 9.74

TMP 1986.078.0082 Humerus I 68 12.21 28 11.36 11.36

TMP 1987.046.0013 Humerus I 373 67.17 156 63.29 63.29

TMP 1988.036.0220 Humerus I 265 47.66 47.66 104 42.19 42.19

TMP 1989.036.0113 Tibia I 112 11.24 34 9.84 9.84

TMP 1989.036.0173 Femur I 132 12.27 12.27 48 12.48 12.48

TMP 1989.036.0306 Radius I 421 64.12 105 69.77 69.77

TMP 1989.036.0415 Femur I 113 10.51 10.51 45 11.70 11.70

TMP 1990.036.0073 Femur I 388 36.08 36.08 181 47.07 47.07

TMP 1990.036.0412 Femur I 118 10.97 10.97 47 12.22 12.22

TMP 1990.036.0418 Humerus I 362 65.03 151 61.26 61.26

TMP 1990.036.0421 Ulna I 452 63.44 63.44 109 61.93 61.93

TMP 1991.036.0055 Fibula I 591 62.10 101 59.94 59.94

259

TMP 1991.036.0296 Radius I 332 50.57 50.57 76 50.50 50.50

TMP 1991.036.0350 Femur I 730 67.88 67.88 280 72.93

TMP 1991.036.0358 Ulna I 574 80.51 146 82.95 82.95

TMP 1991.036.0547 Tibia I 109 10.93 33 9.55 9.55

TMP 1991.036.0733 Tibia I 71 7.16 21 6.08 6.08

TMP 1991.036.0733 Fibula I 60 6.34 12 7.12 7.12

TMP 1991.036.0783 Tibia I 244 24.48 78 22.58 22.58

TMP 1992.036.0054 Femur I 625 58.11 58.11 240 62.52

TMP 1992.036.0125 Tibia I 81 8.11 24 6.95 6.95

TMP 1992.036.0130 Femur I 101 9.42 40 10.40 10.40

TMP 1992.036.0138 Humerus I 73 13.13 13.13 27 10.95 10.95

TMP 1992.036.0165 Tibia I 109 10.93 33 9.55 9.55

TMP 1992.036.0184 Radius I 486 74.02 118 78.41 78.41

TMP 1992.036.0240 Femur I 109 10.14 43 11.18 11.18

TMP 1992.036.0240 Tibia I 121 12.17 37 10.71 10.71

TMP 1992.036.0371 Humerus I 73 13.08 30 12.17 12.17

TMP 1992.036.0413 Radius I 240 36.56 36.56 60 39.87 39.87

TMP 1992.036.0426 Femur I 127 11.82 50 13.00 13.00

TMP 1992.036.0457 Fibula I 110 11.54 21 12.46 12.46

TMP 1992.036.0471 Femur I 112 10.38 44 11.44 11.44

TMP 1992.036.0472 Humerus I 65 11.78 27 10.95 10.95

TMP 1992.036.0487 Fibula I 439 46.16 46.16 77 45.70 45.70

TMP 1992.036.0536 Tibia I 110 11.02 11.02 32 9.26 9.26

TMP 1992.036.0585 Tibia I 100 10.00 30 8.68 8.68

TMP 1992.036.0660 Femur I 120 11.16 11.16 47 12.16

TMP 1992.036.0812 Humerus I 510 91.73 91.73 255 103.45 103.45

TMP 1992.036.0920 Femur I 99 9.21 9.21 43 11.18 11.18

TMP 1992.036.0921 Femur I 97 9.02 9.02 40 10.40 10.40

TMP 1992.036.0963 Humerus I 71 12.77 12.77 34 13.79 13.79

TMP 1992.036.0982 Ulna I 80 11.17 21 11.93 11.93

260

TMP 1992.036.1001 Humerus I 68 12.21 28 11.36 11.36

TMP 1992.036.1048 Ulna I 138 19.34 36 20.45 20.45

TMP 1992.036.1048 Tibia I 118 11.86 36 10.42 10.42

TMP 1992.036.1069 Femur I 122 11.34 48 12.48 12.48

TMP 1992.036.1070 Femur I 104 9.66 41 10.66 10.66

TMP 1992.040.0004 Femur I 81 7.51 32 8.32 8.32

TMP 1992.108.0037 Humerus I 132 23.74 23.74 59 23.94 23.94

TMP 1993.036.0003 Ulna I 79 11.09 11.09 20 11.36 11.36

TMP 1993.036.0123 Tibia I 94 9.37 28 8.10 8.10

TMP 1993.036.0126 Humerus I 493 88.67 88.67 214 86.82 86.82

TMP 1993.036.0274 Humerus I 570 102.52 102.52 212 86.00 86.00

TMP 1993.036.0331 Humerus I 370 66.55 66.55 143 58.01 58.01

TMP 1993.036.0382 Humerus I 266 47.91 111 45.03 45.03

TMP 1993.036.0386 Humerus I 46 8.31 19 7.71 7.71

TMP 1993.036.0417 Femur I 485 45.10 45.10 187 48.61

TMP 1993.036.0418 Ulna I 615 86.32 86.32 139 78.98 78.98

TMP 1993.036.0425 Femur I 1055 98.09 98.09 404 105.09

TMP 1993.036.0506 Femur I 390 36.26 36.26 151 39.16

TMP 1993.040.0015 Radius I 145 22.01 44 29.24 29.24

TMP 1993.066.0024 Radius I 387 58.95 58.95 106 70.43 70.43

TMP 1993.109.0060 Fibula I 448 47.09 78 46.29 46.29

TMP 1993.150.0003 Femur I 104 9.66 41 10.66 10.66

TMP 1994.012.0413 Fibula I 472 49.68 82 48.66 48.66

TMP 1994.012.0425 Tibia I 75 7.47 22 6.37 6.37

TMP 1994.012.0427 Femur I 119 11.10 47 12.22 12.22

TMP 1994.012.0465 Femur I 191 17.71 17.71 85 22.11 22.11

TMP 1994.012.0483 Femur I 101 9.42 40 10.40 10.40

TMP 1994.012.0485 Tibia I 97 9.68 29 8.39 8.39

TMP 1994.012.0486 Tibia I 100 10.00 30 8.68 8.68

TMP 1994.012.0491 Femur I 96 8.94 38 9.88 9.88

261

TMP 1994.012.0492 Femur I 109 10.14 43 11.18 11.18

TMP 1994.012.0493 Tibia I 118 11.86 36 10.42 10.42

TMP 1994.012.0668 Radius I 76 11.53 26 17.28 17.28

TMP 1994.012.0676 Humerus I 61 10.91 25 10.14 10.14

TMP 1994.012.0757 Humerus I 49 8.74 20 8.11 8.11

TMP 1994.012.0785 Humerus I 176 31.61 73 29.61 29.61

TMP 1994.012.0822 Tibia I 140 14.01 43 12.45 12.45

TMP 1994.012.0835 Tibia I 87 8.74 26 7.53 7.53

TMP 1994.012.0840 Tibia A 396 39.68 39.68 147 42.55 42.55

TMP 1994.012.0870 Tibia I 678 67.94 67.94 213 61.51 61.51

TMP 1994.012.0872 Tibia I 500 50.10 50.10 183 52.82 52.82

TMP 1994.012.0889 Tibia I 200 20.04 63 18.23 18.23

TMP 1994.012.0911 Tibia I 84 8.43 25 7.24 7.24

TMP 1994.012.0939 Femur I 76 7.03 30 7.80 7.80

TMP 1994.012.0943 Ulna I 645 90.53 90.53 166 94.22

TMP 1994.012.0944 Tibia I 975 97.70 97.70 343 99.34

TMP 1994.012.0956 Tibia I 78 7.79 23 6.66 6.66

TMP 1994.012.1011 Femur I 805 74.85 805 74.85 309 80.36

TMP 1994.045.0008 Tibia I 125 12.53 12.53 38 11.00 11.00

TMP 1994.045.0009 Tibia I 100 10.00 30 8.68 8.68

TMP 1994.045.0010 Tibia I 109 10.93 33 9.55 9.55

TMP 1994.143.0002 Humerus I 294 52.88 52.88 119 48.28 48.28

TMP 1994.172.0051 Ulna I 77 10.81 10.81 18 10.23 10.23

TMP 1994.172.0113 Fibula I 257 27.02 27.02 44 26.11 26.11

TMP 1995.403.0009 Ulna I 674 94.60 94.60 165 93.75 93.75

TMP 1995.405.0011 Tibia I 55 5.55 16 4.63 4.63

TMP 1995.405.0038 Tibia I 106 10.62 32 9.26 9.26

TMP 1995.405.0050 Femur I 101 9.42 40 10.40 10.40

TMP 1996.012.0006 Humerus I 195 35.05 81 32.86 32.86

TMP 1996.012.0157 Femur I 127 11.82 50 13.00 13.00

262

TMP 1996.012.0160 Tibia I 109 10.93 33 9.55 9.55

TMP 1996.012.0163 Tibia I 97 9.68 29 8.39 8.39

TMP 1996.012.0170 Femur I 114 10.62 45 11.70 11.70

TMP 1996.012.0172 Femur I 161 14.97 14.97 59 15.34 15.34

TMP 1996.012.0175 Femur I 125 11.62 11.62 42 10.92 10.92

TMP 1996.012.0435 Fibula I 88 9.21 17 10.09 10.09

TMP 1996.014.0011 Humerus I 513 92.35 215 87.22 87.22

TMP 1996.014.0100 Ulna I 514 72.09 131 74.43 74.43

TMP 1997.012.0126 Tibia I 116 11.57 11.57 31 8.97 8.97

TMP 1997.012.0154 Humerus I 70 12.64 29 11.76 11.76

TMP 1997.012.0166 Femur I 124 11.48 11.48 46 11.96 11.96

TMP 1997.012.0167 Humerus I 112 20.14 20.14 40 16.23 16.23

TMP 1997.012.0173 Femur I 126 11.72 11.72 49 12.74 12.74

TMP 1997.012.0177 Tibia I 90 9.06 27 7.81 7.81

TMP 1997.012.0185 Tibia I 106 10.62 32 9.26 9.26

TMP 1997.012.0196 Tibia I 103 10.31 31 8.97 8.97

TMP 1997.012.0197 Tibia I 109 10.93 33 9.55 9.55

TMP 1997.012.0216 Tibia I 143 14.33 14.33 41 11.87 11.87

TMP 1998.058.0001 Humerus A 260 46.76 46.76 108 43.77

TMP 1998.058.0001 Radius A 307 46.76 46.76 77 50.88

TMP 1998.058.0001 Ulna A 303 42.53 42.53 77 43.84

TMP 1998.058.0001 Femur A 528 49.09 49.09 203 52.89

TMP 1998.058.0001 Tibia A 460 46.09 46.09 153 44.33

TMP 1998.058.0001 Fibula A 447 47.00 47.00 75 44.71

TMP 1998.093.0025 Tibia I 103 10.31 31 8.97 8.97

TMP 1998.093.0032 Tibia I 115 11.55 35 10.13 10.13

TMP 1998.093.0033 Ulna I 76 10.63 20 11.36 11.36

TMP 1998.093.0060 Tibia I 115 11.55 35 10.13 10.13

TMP 1998.093.0061 Tibia I 118 11.86 36 10.42 10.42

TMP 1998.093.0121 Femur I 161 14.95 63 16.38 16.38

263

TMP 1998.093.0132 Femur I 109 10.14 43 11.18 11.18

TMP 1998.093.0136 Radius I 200 30.46 30.46 59 39.20 39.20

TMP 1998.093.0176 Fibula I 755 79.38 127 75.37 75.37

TMP 1999.055.0350 Femur I 325 30.22 30.22 161 41.87 41.87

TMP 2000.012.0045 Humerus I 80 14.37 33 13.39 13.39

TMP 2000.012.0048 Femur I 108 10.04 10.04 42 10.92 10.92

TMP 2000.012.0049 Femur I 140 13.02 55 14.30 14.30

TMP 2000.012.0162 Fibula I 457 48.05 48.05 75 44.51 44.51

TMP 2001.012.0006 Radius I 517 78.75 78.75 112 74.42 74.42

TMP 2001.012.0016 Humerus I 71 12.77 12.77 30 12.17 12.17

TMP 2001.012.0089 Femur I 203 18.87 18.87 79 20.49

TMP 2002.012.0004 Humerus I 75 13.51 31 12.58 12.58

TMP 2002.012.0095 Humerus I 68 12.21 28 11.36 11.36

TMP 2003.012.0073 Humerus I 61 10.91 25 10.14 10.14

TMP 2003.012.0115 Fibula I 922 96.91 153 90.80 90.80

TMP 2004.113.0030 Tibia I 97 9.68 29 8.39 8.39

TMP 2005.009.0084 Ulna I 360 50.53 50.53 85 48.30 48.30

TMP 2005.012.0062 Humerus I 99 17.83 41 16.63 16.63

TMP 2005.049.0084 Femur I 214 19.90 19.90 90 23.41 23.41

TMP 2006.012.0134 Humerus I 128 23.00 53 21.50 21.50

TMP 2007.014.0001 Femur I 845 78.57 78.57 332 86.35 86.35

TMP 2007.014.0005 Femur I 1040 96.70 96.70 398 103.61

TMP 2007.014.0008 Humerus I 483 86.81 202 81.95 81.95

TMP 2007.014.0009 Humerus I 350 62.95 62.95 131 53.14 53.14

TMP 2007.014.0011 Tibia I 774 77.60 267 77.28 77.28

TMP 2007.020.0064 Humerus I 94 16.91 16.91 43 17.44 17.44

TMP 2007.020.0098 Femur I 131 12.18 12.18 47 12.22 12.22

TMP 2007.020.0099 Tibia I 107 10.72 10.72 28 8.10 8.10

TMP 2007.020.0110 Femur I 207 19.25 19.25 85 22.11 22.11

TMP 2008.012.0008 Tibia I 106 10.62 10.62 29 8.39 8.39

264

TMP 2009.012.0022 Humerus I 177 31.83 31.83 73 29.61 29.61

TMP 2011.012.0269 Tibia I 144 14.43 14.43 47 13.60 13.60

TMP 2011.012.0292 Tibia I 115 11.52 11.52 29 8.39 8.39

TMP 2014.012.0062 Femur I 101 9.42 40 10.40 10.40

TMP 2016.012.0068 Tibia I 109 10.93 33 9.55 9.55

TMP 2016.012.0124 Tibia I 701 70.22 240 69.46 69.46

TMP 2016.012.0125 Tibia I 823 82.49 285 82.49 82.49

TMP 2016.012.0132 Tibia I 98 9.84 30 8.54 8.54

TMP 2016.012.0192 Tibia I 985 98.67 345 99.86 99.86

TMP 2016.012.0193 Humerus I 561 100.87 235 95.33 95.33

TMP 2016.012.0194 Tibia I 646 64.72 220 63.68 63.68

TMP 2016.012.0195 Tibia I 891 89.26 310 89.73 89.73

UALVP 13 Humerus A 568 102.15 238 96.55 96.55

UALVP 13 Femur A 890 82.75 82.75 265 68.92 68.92

UALVP 13 Femur A 1145 106.42 106.42 335 87.13 87.13

UALVP 13 Femur A 790 73.45 73.45 385 100.13 100.13

UALVP 13 Tibia A 1070 107.21 107.21 342 98.99 98.99

UALVP 13 Tibia A 975 97.70 97.70 343 99.34

UALVP 13 Fibula A 996 104.73 104.73 155 91.99 91.99

UALVP 300 Humerus A 505 90.83 90.83 213 86.45

UALVP 300 Femur A 815 75.78 75.78 313 81.35

UALVP 300 Femur A 1010 93.91 93.91 387 100.65

UALVP 300 Tibia A 895 89.68 89.68 313 90.62

UALVP 300 Fibula A 860 90.43 90.43 145 85.82

UALVP 302? Humerus I 510 91.73 91.73 199 80.73 80.73

UALVP 47945 Tibia I 600 60.12 60.12 218 63.10 63.10

UALVP 49015 Humerus I 255 45.86 45.86 115 46.65 46.65

UALVP 49511 Humerus I 525 94.42 94.42 227 92.09 92.09

UALVP 52745 Femur I 1080 100.42 100.42 414 107.56

UALVP 52772 Humerus I 485 87.23 87.23 213 86.41 86.41

265

UALVP 54643 Femur I 122 11.34 11.34 59 15.34 15.34

UALVP 54684 Femur I 139 12.92 12.92 51 13.26 13.26

UALVP 54792 Humerus I 480 86.33 86.33 202 82.06

UALVP 55172 Fibula I 545 57.31 57.31 105 62.31 62.31

UALVP 55173 Tibia I 835 83.67 83.67 295 85.38 85.38

UALVP 55465 Fibula I 575 60.46 60.46 97 57.46

UALVP 7-21 Femur I 750 69.74 69.74 288 74.92

266

Appendix 3-1. Total length and minimum diaphyseal circumference data of all specimens used

in Ruth Mason Dinosaur Quarry (RMDQ) analyses. Estimated values were based on the OLS

regressions (Supplementary Table S3-1). Percentage values were scaled to the largest

corresponding element from RMDQ.

Specimen # Field # Element Collection RawTL RawTL%Max EstTL EstTL%Max RawCirc RawCirc%Max EstCirc EstCirc%Max

6226 Femur BHI 533 43.30 533 43.30 190 40.12

8860 Femur BHI 533 43.30 533 43.30 190 40.12

7322 Tibia BHI 485 46.57 485 46.57 175 50.02 175 48.61

8559 Fibula BHI 445 44.87

91-1930 Fibula BHI 445 44.87

7182 Tibia BHI 500 48.01 500 48.01 178 49.32

4348 Tibia BHI 505 48.49 505 48.49 205 58.60 205 56.94

90-692 Fibula BHI 457 46.15

3051 Tibia BHI 515 49.45 515 49.45 192 54.88 192 53.33

91-0884 Radius BHI 254 40.00

6212 Fibula BHI 463 46.74

6370 Tibia BHI 520 49.93 520 49.93 184 51.11

3218 Femur BHI 584 47.42 584 47.42 210 44.31

7114 Femur BHI 584 47.42 584 47.42 210 44.31

90-223 Femur BHI 584 47.42 584 47.42 210 44.31

91-0123 Fibula BHI 470 47.44

5441 Femur BHI 597 48.45 597 48.45 215 45.36

5324 Tibia BHI 535 51.37 535 51.37 189 52.46

90-784 Tibia BHI 535 51.38 535 51.38 189 52.47

6405 Tibia BHI 540 51.85 540 51.85 190 52.90

182 Femur BHI 605 49.11 605 49.11 218 45.93 218 45.93

8480 Tibia BHI 540 51.86 540 51.86 190 52.91

3515 Fibula BHI 483 48.72

3162 Fibula BHI 483 48.72

7035 Femur BHI 610 49.48 610 49.48 220 46.41

267

8685 Femur BHI 610 49.48 610 49.48 220 46.41

90-337 Femur BHI 610 49.48 610 49.48 220 46.41

90-252 Tibia BHI 545 52.33 545 52.33 192 53.35

6542 Tibia BHI 550 52.81 550 52.81 194 53.80

67603 116 Tibia ROM 555 53.29 555 53.29 185 52.74 185 51.25

1208 Femur BHI 625 50.73 625 50.73 226 47.69

91-0499 Tibia BHI 559 53.65 559 53.66 196 54.57

90-638 Tibia BHI 559 53.65 559 53.66 196 54.58

7651 Tibia BHI 559 53.66 559 53.66 196 54.58

90-578 Tibia BHI 559 53.66 559 53.66 197 54.59

8481 Tibia BHI 559 53.67 559 53.66 197 54.59

2104 Tibia BHI 560 53.77 560 53.77 197 54.69

5364 Tibia BHI 560 53.78 560 53.77 197 54.70

90-719 Femur BHI 629 51.03 629 51.03 228 48.00

8181 Ulna BHI 305 42.86

3013 Femur BHI 635 51.55 635 51.55 230 48.53

3211 Femur BHI 635 51.55 635 51.55 230 48.53

5454 Femur BHI 635 51.55 635 51.55 230 48.53

8277 Femur BHI 635 51.55 635 51.55 230 48.53

4433 Tibia BHI 570 54.73 570 54.73 200 55.58

147 Fibula BHI 508 51.28

7012 Fibula BHI 508 51.28

90-759 Fibula BHI 508 51.28

Z8034 Fibula BHI 508 51.28

67601 7321 Tibia ROM 575 55.21 575 55.21 194 55.46 194 53.89

7889 Femur BHI 648 52.58 648 52.58 235 49.59

3042 Tibia BHI 580 55.69 580 55.69 203 56.47

90-834 Tibia BHI 580 55.70 580 55.69 203 56.47

7246 Radius BHI 287 45.20

8905 Humerus BHI 330 48.15 330 48.15 126 47.59

Z8037 Tibia BHI 584 56.10 584 56.10 205 56.84

91-1105 Fibula BHI 521 52.56

B 443 2010.45.100 Tibia TCM 585 56.17 585 56.17 198 56.60 198 55.00

268

8823 Tibia BHI 585 56.17 585 56.17 205 56.91

8484 Tibia BHI 585 56.18 585 56.17 205 56.92

6401 Femur BHI 660 53.61 660 53.61 240 50.65

6402 Femur BHI 660 53.61 660 53.61 240 50.65

6445 Femur BHI 660 53.61 660 53.61 240 50.65

6521 Femur BHI 660 53.61 660 53.61 240 50.65

90-477 Fibula BHI 527 53.21

8983 Fibula BHI 533 53.85

Z7003 Fibula BHI 535 54.01

5453 Femur BHI 673 54.64 673 54.64 245 51.71

90-234 Femur BHI 673 54.64 673 54.64 245 51.71

3363 Humerus BHI 340 49.58 340 49.58 150 56.60 150 56.60

67602 91-1569 Femur ROM 675 54.79 675 54.79 255 53.73 255 53.73

91-0051 Fibula BHI 540 54.49

91-1724 Fibula BHI 540 54.51

Z8036 Humerus BHI 343 50.00 343 50.00 131 49.41

8211 Radius BHI 300 47.20

8537 Tibia BHI 610 58.54 610 58.54 213 59.09

209 Tibia BHI 610 58.57 610 58.57 200 57.17 200 55.56

90-549 Tibia BHI 610 58.58 610 58.57 213 59.13

3293 Ulna BHI 330 46.43

8274 Ulna BHI 330 46.43

3311 Fibula BHI 545 55.02

39 Femur BHI 686 55.67 686 55.67 250 52.78

7236 Femur BHI 686 55.67 686 55.67 250 52.78

7259 Femur BHI 686 55.67 686 55.67 250 52.78

8979 Femur BHI 686 55.67 686 55.67 250 52.78

Z8158 Femur BHI 686 55.67 686 55.67 250 52.78

90-058 Fibula BHI 546 55.13

90-059 Fibula BHI 546 55.13

3 Tibia BHI 615 59.06 615 59.06 214 61.17 214 59.44

1058 Femur BHI 690 56.01 690 56.01 260 54.78 260 54.78

8689 Fibula BHI 550 55.52

269

220 Humerus BHI 350 51.04 350 51.04 145 54.72 145 54.75

2117 Radius BHI 305 48.00

260 Tibia BHI 620 59.54 620 59.54 216 60.01

7713 Fibula BHI 555 56.03

B 199 Femur TCM 700 56.82 700 56.82 265 55.84 265 55.84

6255 Tibia BHI 625 60.02 625 60.02 218 60.45

6469 Tibia BHI 625 60.02 625 60.02 218 60.45

6310 Tibia BHI 625 60.02 625 60.02 218 60.46

6576 Fibula BHI 559 56.41

6615 Fibula BHI 559 56.41

8939 Fibula BHI 559 56.41

8940 Fibula BHI 559 56.41

5355 Humerus BHI 355 51.76 355 51.76 136 51.14

1042 Fibula BHI 560 56.53

3364 Humerus BHI 356 51.85 356 51.85 136 51.23

90-523 Humerus BHI 356 51.85 356 51.85 138 51.94

8177 Humerus BHI 356 51.85 356 51.85 138 51.96

7307 Humerus BHI 356 51.85 356 51.85 138 52.04

67798 3217 Femur ROM 705 57.19 256 53.94 256 53.94

91-1286 Tibia BHI 630 60.49 630 60.49 219 60.88

86 Tibia BHI 630 60.50 630 60.50 219 60.89

8998 Ulna BHI 343 48.21

5429 Fibula BHI 565 57.04

8820 Femur BHI 711 57.73 711 57.73 261 54.92

3078 Tibia BHI 635 60.98 635 60.98 221 61.33

Z8159 Tibia BHI 635 60.98 635 60.98 221 61.33

6309 Tibia BHI 635 60.99 635 60.98 221 61.34

8847 Radius BHI 312 49.20

73851 4237 Humerus ROM 360 52.49 360 52.49 128 48.30 128 48.30

OS 278 2004.111.53 Humerus TCM 360 52.49 360 52.49 129 48.68 129 48.68

? Humerus BHI 360 52.49 360 52.49 133 50.19 133 50.19

B 61 2007.207.77 Fibula TCM 567 57.24

102 Fibula BHI 570 57.54

270

8479 Femur BHI 720 58.45 720 58.45 264 55.66

8686 Tibia BHI 645 61.94 645 61.94 224 62.21

S4 Tibia BHI 645 61.95 645 61.94 224 62.22

7239 Fibula BHI 575 58.05

3247 Radius BHI 318 50.00

5455 Radius BHI 318 50.00

8473 Radius BHI 318 50.00

91-1032 Ulna BHI 349 49.11

OS 170 2004.111.49 Humerus TCM 366 53.37 366 53.37 130 49.06 130 49.06

7354 Tibia BHI 650 62.42 650 62.42 226 62.65

7495 Humerus BHI 368 53.70 368 53.70 141 53.05

91-1424 Femur BHI 732 59.38 732 59.38 269 56.63

3266 Humerus BHI 370 53.95 370 53.95 147 55.47 147 55.47

2409 Tibia BHI 655 62.90 655 62.90 227 63.09

90-233 Tibia BHI 655 62.91 655 62.90 227 63.10

91-0104 Humerus BHI 371 54.03 140 52.83 140 52.83

90-579 Fibula BHI 584 58.97

91-1288 Fibula BHI 584 58.97

5335 Ulna BHI 356 50.00

6539 Ulna BHI 356 50.00

6559 Ulna BHI 356 50.00

8491 Ulna BHI 356 50.00

1167 Femur BHI 737 59.79 737 59.79 271 57.06

5405 Femur BHI 737 59.79 737 59.79 271 57.06

6311 Femur BHI 737 59.79 737 59.79 271 57.06

7493 Femur BHI 737 59.79 737 59.79 271 57.06

7589 Femur BHI 737 59.79 737 59.79 271 57.06

8539 Femur BHI 737 59.79 737 59.79 271 57.06

90-249 Femur BHI 737 59.79 737 59.79 271 57.06

90-331 Femur BHI 737 59.79 737 59.79 271 57.06

91-0415 Femur BHI 737 59.79 737 59.79 271 57.06

? Humerus BHI 372 54.24 372 54.24 142 53.58 142 53.58

8424 Tibia BHI 660 63.38 660 63.38 229 63.53

271

8482 Tibia BHI 660 63.39 660 63.38 229 63.53

8944 Radius BHI 325 51.20

91-0216 Humerus BHI 375 54.63 375 54.63 143 53.96

73849 4432 Humerus ROM 375 54.68 375 54.68 136 51.32 136 51.32

5426 Fibula BHI 595 60.06

91-0161 Tibia BHI 670 64.34 670 64.34 232 64.40

4658 Fibula BHI 597 60.26

7944 Fibula BHI 597 60.26

3478 Radius BHI 330 52.00

4364 Radius BHI 330 52.00

5135 Radius BHI 330 52.00

8386 Radius BHI 330 52.00

91-0420 Radius BHI 330 52.00

91-1720 Humerus BHI 380 55.41 380 55.41 140 52.83 140 52.87

7042 Humerus BHI 380 55.41 380 55.41 147 55.47 147 55.51

4431 Humerus BHI 381 55.56 381 55.56 145 54.87

91-0718 Humerus BHI 381 55.56 381 55.56 148 55.66

6599 Tibia BHI 675 64.82 675 64.82 233 64.84

2267 Humerus BHI 382 55.70 382 55.70 145 54.72 145 54.68

67797 117 Tibia ROM 677 65.01 233 66.60 233 64.72

90-628 Tibia BHI 679 65.24 679 65.24 235 65.23

6274 Tibia BHI 680 65.30 680 65.30 235 65.28

4140 Tibia BHI 680 65.31 680 65.30 237 67.75 237 65.83

5501 Femur BHI 762 61.86 762 61.86 281 59.21

7149 Femur BHI 762 61.86 762 61.86 281 59.21

7940 Femur BHI 762 61.86 762 61.86 281 59.21

8046 Femur BHI 762 61.86 762 61.86 281 59.21

8535 Femur BHI 762 61.86 762 61.86 281 59.21

8540 Femur BHI 762 61.86 762 61.86 281 59.21

8799 Femur BHI 762 61.86 762 61.86 281 59.21

208 Humerus BHI 385 56.14 385 56.14 145 54.72 145 54.72

7822 Ulna BHI 368 51.79

5285 Radius BHI 335 52.80

272

3186 Fibula BHI 610 61.54

5140 Fibula BHI 610 61.54

90-411 Fibula BHI 610 61.54

3053 Fibula BHI 610 61.58

90-845 Tibia BHI 685 65.78 685 65.78 237 65.72

Z8149 Tibia BHI 686 65.85 686 65.85 237 65.78

7355 Tibia BHI 686 65.85 686 65.85 237 65.79

91-0570 Tibia BHI 686 65.86 686 65.85 237 65.79

91-0453 Tibia BHI 686 65.86 686 65.85 237 65.79

5230 Femur BHI 770 62.51 770 62.51 284 59.89

S3 Femur BHI 770 62.51 770 62.51 284 59.89

3040 Tibia BHI 690 66.26 690 66.26 238 66.15

3170 Tibia BHI 690 66.27 690 66.26 238 66.16

91-1729 Fibula BHI 616 62.18

6616 Tibia BHI 695 66.74 695 66.74 230 65.75 230 63.89

5312 Tibia BHI 695 66.74 695 66.74 241 68.89 240 66.59

8276 Tibia BHI 695 66.75 695 66.74 240 66.60

B 583 2011.16.52 Ulna TCM 376 52.87

3749 Humerus BHI 394 57.41 394 57.41 150 56.69

6306 Humerus BHI 394 57.41 394 57.41 152 57.49

3748 Radius BHI 343 54.00

91-1442 Radius BHI 343 54.00

90-529 Femur BHI 781 63.40 781 63.40 289 60.82

OS 172 2004.111.52 Humerus TCM 395 57.60 395 57.60 146 55.09 146 55.09

5151 Humerus BHI 395 57.60 395 57.60 155 58.49 155 58.49

7977 Tibia BHI 699 67.07 699 67.07 241 66.94

90-839 Fibula BHI 622 62.82

B 336 Femur TCM 783 63.56 783 63.56 286 60.26 286 60.26

8536 Femur BHI 787 63.92 787 63.92 291 61.36

8538 Femur BHI 787 63.92 787 63.92 291 61.36

8602 Femur BHI 787 63.92 787 63.92 291 61.36

8722 Femur BHI 787 63.92 787 63.92 291 61.36

90-193 Femur BHI 787 63.92 787 63.92 291 61.36

273

90-568 Femur BHI 787 63.92 787 63.92 291 61.36

91-0919 Tibia BHI 705 67.70 705 67.70 243 67.46

2124 Humerus BHI 400 58.33 400 58.33 160 60.38 160 60.38

90-265 Tibia BHI 711 68.29 711 68.29 245 68.00

Z8151 Tibia BHI 711 68.30 711 68.29 245 68.01

90-754 Tibia BHI 711 68.30 711 68.29 245 68.01

2224 Fibula BHI 635 64.10

6105 Fibula BHI 635 64.10

90-756 Fibula BHI 635 64.10

2154 Tibia BHI 715 68.66 715 68.66 240 68.61 240 66.67

Z7006 Fibula BHI 640 64.61

127 Humerus BHI 406 59.26 406 59.26 155 58.51

5432 Humerus BHI 406 59.26 406 59.26 157 59.25

2414 Humerus BHI 406 59.26 406 59.26 157 59.28

5165 Humerus BHI 406 59.26 406 59.26 157 59.30

67795 7663 Tibia ROM 720 69.14 720 69.14 238 67.89 238 65.97

32 Fibula BHI 642 64.81

2198 Radius BHI 356 56.00

3241 Radius BHI 356 56.00

6365 Radius BHI 356 56.00

6593 Radius BHI 356 56.00

8756 Radius BHI 356 56.00

90-861 Radius BHI 356 56.00

91-1892 Radius BHI 356 56.00

Z7005 Fibula BHI 645 65.11

5415 Femur BHI 813 65.98 813 65.98 302 63.53

5509 Femur BHI 813 65.98 813 65.98 302 63.53

6442 Femur BHI 813 65.98 813 65.98 302 63.53

6626 Femur BHI 813 65.98 813 65.98 302 63.53

8934 Femur BHI 813 65.98 813 65.98 302 63.53

90-156 Femur BHI 813 65.98 813 65.98 302 63.53

90-782 Femur BHI 813 65.98 813 65.98 302 63.53

B 99 2007.207.97 Femur TCM 815 66.16 815 66.16 287 60.47 287 60.47

274

8907 Ulna BHI 394 55.36

B 53 2007.207.22 Radius TCM 360

1046 Humerus BHI 415 60.51 415 60.51 158 59.74

7144 Humerus BHI 415 60.51 415 60.51 160 60.38 160 60.42

91-0308 Fibula BHI 654 66.03

B 656 2011.16.127 Humerus TCM 416 60.66 416 60.66 155 58.49 155 58.49

2173 Femur BHI 825 66.97 825 66.97 320 67.43 320 67.43

7774 Radius BHI 363 57.20

90-104 Tibia BHI 740 71.06 740 71.06 254 70.51

8369 Humerus BHI 419 61.11 419 61.11 160 60.33

6278 Fibula BHI 660 66.67

B 505 2010.45.41 Tibia TCM 745 71.54 745 71.54 249 71.18 249 69.17

3077 Femur BHI 838 68.04 838 68.04 312 65.70

5430 Femur BHI 838 68.04 838 68.04 312 65.70

7352 Femur BHI 838 68.04 838 68.04 312 65.70

7509 Femur BHI 838 68.04 838 68.04 312 65.70

7711 Femur BHI 838 68.04 838 68.04 312 65.70

8179 Femur BHI 838 68.04 838 68.04 312 65.70

8881 Femur BHI 838 68.04 838 68.04 312 65.70

8981 Femur BHI 838 68.04 838 68.04 312 65.70

91-0871 Femur BHI 838 68.04 838 68.04 312 65.70

3345 Radius BHI 368 58.00

7814 Radius BHI 368 58.00

8859 Radius BHI 368 58.00

25 Tibia BHI 750 72.02 750 72.02 260 74.32 260 72.22

B 506 2010.45.84 Femur TCM 843 68.43 843 68.43 300 63.21 300 63.21

1311 Femur BHI 845 68.59 845 68.59 315 66.28

B 200 2008.211.120 Tibia TCM 757 72.69 757 72.69 253 72.32 253 70.28

Z8031 Femur BHI 851 69.07 851 69.07 317 66.78

7147 Tibia BHI 760 72.98 760 72.98 260 72.25

3423 Humerus BHI 430 62.70 430 62.70 164 61.89

7658 Tibia BHI 762 73.17 762 73.17 261 72.42

90-858 Tibia BHI 762 73.18 762 73.17 261 72.43

275

126 Humerus BHI 432 62.96 432 62.96 165 62.14

6087 Humerus BHI 432 62.96 432 62.96 167 62.83

3129 Humerus BHI 432 62.96 432 62.96 167 62.87

1300 Humerus BHI 432 62.96 432 62.96 167 62.94

4631 Humerus BHI 432 62.96 432 62.96 167 62.98

B 33 2007.207.95 Ulna TCM 415 58.35

2263 Fibula BHI 685 69.15

7283 Fibula BHI 685 69.15

7656 Humerus BHI 435 63.43 435 63.43 170 64.15 170 64.15

6613 Fibula BHI 686 69.23

90-426 Fibula BHI 686 69.23

90-567 Fibula BHI 686 69.23

Z7004 Fibula BHI 686 69.23

3533 Femur BHI 864 70.10 864 70.10 322 67.87

6618 Femur BHI 864 70.10 864 70.10 322 67.87

7235 Femur BHI 864 70.10 864 70.10 322 67.87

5019 Fibula BHI 687 69.35

67799 2193 Femur ROM 865 70.22 865 70.22 318 67.00 318 67.00

7359 Fibula BHI 688 69.45

U of

37 Radius Chicago 380

5468 Radius BHI 381 60.00

6245 Radius BHI 381 60.00

7927 Radius BHI 381 60.00

91-1681 Radius BHI 381 60.00

91-1825 Radius BHI 381 60.00

7323 Ulna BHI 419 58.93

90-554 Ulna BHI 419 58.93

8687 Humerus BHI 440 64.16 440 64.16 169 63.77 169 63.77

6229 Tibia BHI 780 74.90 780 74.90 266 73.98

B 545 2011.16.40 Humerus TCM 442 64.50 169 63.77 169 63.77

6371 Tibia BHI 785 75.38 785 75.38 268 74.41

SF 21 2008.211.120 Fibula TCM 700 70.66

276

8904 Humerus BHI 445 64.81 445 64.81 170 63.96

91-0872 Humerus BHI 445 64.81 445 64.81 172 64.75

6275 Tibia BHI 787 75.61 787 75.61 269 74.62

90-413 Tibia BHI 787 75.61 787 75.61 269 74.62

7659 Tibia BHI 788 75.62 787 75.61 269 74.62

4277 Femur BHI 889 72.16 889 72.16 332 70.05

7939 Femur BHI 889 72.16 889 72.16 332 70.05

4176 Femur BHI 890 72.25 890 72.25 302 63.63 302 63.63

7356 Humerus BHI 450 65.56 450 65.56 171 64.69

7131 Ulna BHI 432 60.71

6190 Fibula BHI 711 71.79

7037 Fibula BHI 711 71.79

91-0337 Fibula BHI 711 71.79

Z7002 Fibula BHI 711 71.79

67796 6406 Humerus ROM 452 65.94 173 65.28 173 65.28

3102 Tibia BHI 800 76.82 800 76.82 273 75.70

5176 Tibia BHI 800 76.83 800 76.82 273 75.71

SF 82 Ulna TCM 433 60.88

5418 Radius BHI 394 62.00

B 782 2012.11.44 Ulna TCM 435 61.16

7892 Humerus BHI 455 66.35 455 66.35 165 62.26 165 62.26

B 498 2010.45.86 Fibula TCM 717 72.38

91-1597 Radius BHI 396 62.40

3708 Humerus BHI 457 66.67 457 66.67 174 65.78

6277 Humerus BHI 457 66.67 457 66.67 176 66.57

90-653 Ulna BHI 438 61.61

B 853 Tibia TCM 810 77.78 810 77.78 277 79.18 277 76.94

91-0370 Fibula BHI 724 73.08

Z8150 Tibia BHI 813 78.04 813 78.05 276 76.80

Z8130 Tibia BHI 813 78.04 813 78.05 276 76.80

7218 Tibia BHI 813 78.05 813 78.05 277 76.81

8232 Tibia BHI 813 78.05 813 78.05 277 76.81

7657 Tibia BHI 813 78.06 813 78.05 277 76.82

277

3563 Humerus BHI 460 67.07 460 67.07 175 66.18

90-482 Radius BHI 400 63.00

7184 Fibula BHI 725 73.19

1218 Femur BHI 914 74.23 914 74.23 343 72.24

6209 Femur BHI 914 74.23 914 74.23 343 72.24

6211 Femur BHI 914 74.23 914 74.23 343 72.24

6492 Femur BHI 914 74.23 914 74.23 343 72.24

7116 Femur BHI 914 74.23 914 74.23 343 72.24

7353 Femur BHI 914 74.23 914 74.23 343 72.24

91-1689 Radius BHI 404 63.60

6366 Ulna BHI 445 62.50

B 657 Tibia TCM 825 79.22 825 79.22 304 86.90 304 84.44

7148 Fibula BHI 735 74.20

3426 Radius BHI 406 64.00

8314 Radius BHI 406 64.00

91-1891 Radius BHI 406 64.00

6574 Fibula BHI 737 74.36

7631 Fibula BHI 737 74.36

8544 Fibula BHI 737 74.36

90-489 Fibula BHI 737 74.36

B 852 2012.11.54 Ulna TCM 448 62.99

3731 Humerus BHI 470 68.52 470 68.52 179 67.60

B 846 2012.11.39 Radius TCM 410

7931 Fibula BHI 745 75.21

B 164 2008.211.52 Ulna TCM 453 63.70

7807 Tibia BHI 838 80.49 838 80.49 284 78.99

8640 Tibia BHI 838 80.50 838 80.49 284 79.00

4716 Femur BHI 940 76.29 940 76.29 353 74.43

4742 Femur BHI 940 76.29 940 76.29 353 74.43

6308 Femur BHI 940 76.29 940 76.29 353 74.43

6403 Femur BHI 940 76.29 940 76.29 353 74.43

7216 Femur BHI 940 76.29 940 76.29 353 74.43

7776 Femur BHI 940 76.29 940 76.29 353 74.43

278

8935 Femur BHI 940 76.29 940 76.29 353 74.43

8936 Femur BHI 940 76.29 940 76.29 353 74.43

8980 Femur BHI 940 76.29 940 76.29 353 74.43

91-0953 Femur BHI 940 76.29 940 76.29 353 74.43

91-1518 Femur BHI 940 76.29 940 76.29 353 74.43

B 290 2009.71.26 Ulna TCM 456 64.12

2107 Ulna BHI 457 64.29

6538 Ulna BHI 457 64.29

7361 Ulna BHI 457 64.29

3527 Humerus BHI 480 69.99 480 69.99 183 69.04

2379 Tibia BHI 850 81.62 850 81.62 305 87.19 305 84.72

6014 Radius BHI 419 66.00

6507 Radius BHI 419 66.00

7289 Radius BHI 419 66.00

8476 Radius BHI 419 66.00

258 Humerus BHI 483 70.37 483 70.37 184 69.42

3597 Humerus BHI 483 70.37 483 70.37 186 70.11

91-0920 Humerus BHI 483 70.37 483 70.37 186 70.13

7587 Humerus BHI 483 70.37 483 70.37 186 70.17

4519 Tibia BHI 855 82.10 855 82.10 290 80.44

6344 Fibula BHI 762 76.92

91-1172 Tibia BHI 860 82.58 860 82.58 291 80.86

7351 Femur BHI 965 78.35 965 78.35 364 76.63

8425 Femur BHI 965 78.35 965 78.35 364 76.63

90-173 Femur BHI 965 78.35 965 78.35 364 76.63

Z8030 Femur BHI 965 78.35 965 78.35 364 76.63

8641 Tibia BHI 864 82.93 864 82.93 292 81.17

91-0058 Tibia BHI 864 82.93 864 82.93 292 81.18

8856 Tibia BHI 864 82.94 864 82.93 292 81.18

7281 Humerus BHI 490 71.45 490 71.45 187 70.47

91-1285 Radius BHI 427 67.20

4166 Femur BHI 975 79.15 975 79.15 367 77.33 367 77.33

B 64 2007.207.86 Femur TCM 976 79.23 976 79.23 365 76.91 365 76.91

279

67793 6440 Tibia ROM 875 84.02 875 84.02 275 78.61 275 76.39

3171 Tibia BHI 875 84.03 875 84.02 296 82.16

3669 Radius BHI 432 68.00

3699 Radius BHI 432 68.00

4736 Radius BHI 432 68.00

5410 Radius BHI 432 68.00

90-786 Tibia BHI 883 84.76 883 84.76 298 82.80

7185 Fibula BHI 787 79.49

7588 Fibula BHI 787 79.49

8279 Fibula BHI 787 79.49

91-0131 Fibula BHI 787 79.49

91-1284 Humerus BHI 500 72.91 500 72.91 200 75.47 200 75.47

7632 Femur BHI 991 80.41 991 80.41 374 78.83

B 356 2008.211.119 Tibia TCM 887 85.17 887 85.17 274 78.32 274 76.11

4276 Tibia BHI 889 85.37 889 85.37 300 83.35

Z8032 Tibia BHI 889 85.37 889 85.37 300 83.35

8603 Tibia BHI 889 85.38 889 85.37 300 83.36

8879 Tibia BHI 890 85.46 890 85.46 321 91.76 321 89.17

91-1645 Ulna BHI 483 67.86

7219 Humerus BHI 505 73.64 505 73.64 194 73.21 194 73.21

5444 Humerus BHI 505 73.64 505 73.64 195 73.58 195 73.58

B 36 2007.207.1 Fibula TCM 797 80.46

3646 Femur BHI 1003 81.44 1003 81.44 379 79.93

7320 Femur BHI 1003 81.44 1003 81.44 379 79.93

8903 Femur BHI 1003 81.44 1003 81.44 379 79.93

4443 Humerus BHI 508 74.07 508 74.07 194 73.05

91-1296 Humerus BHI 508 74.07 508 74.07 195 73.66

8724 Humerus BHI 508 74.07 508 74.07 195 73.70

4727 Humerus BHI 508 74.07 508 74.07 196 73.81

8426 Humerus BHI 508 74.07 508 74.07 196 73.85

5511 Fibula BHI 803 81.06

90-564 Tibia BHI 902 86.59 902 86.59 304 84.43

90-857 Tibia BHI 902 86.59 902 86.59 304 84.44

280

4621 Humerus BHI 510 74.37 510 74.37 186 70.19 186 70.19

6159 Humerus BHI 510 74.37 510 74.37 198 74.72 198 74.72

91-0369 Ulna BHI 489 68.75

91-0851 Ulna BHI 489 68.75

6447 Femur BHI 1016 82.47 1016 82.47 385 81.04

7142 Femur BHI 1016 82.47 1016 82.47 385 81.04

7234 Femur BHI 1016 82.47 1016 82.47 385 81.04

5361 Fibula BHI 808 81.57

4546 Fibula BHI 813 82.05

3571 Tibia BHI 914 87.80 914 87.80 308 85.52

90-192 Tibia BHI 914 87.81 914 87.80 308 85.52

8797 Tibia BHI 915 87.81 914 87.80 308 85.52

6171 Tibia BHI 915 87.86 915 87.86 308 85.57

6409 Ulna BHI 495 69.64

91-1500 Radius BHI 451 71.00

6372 Femur BHI 1029 83.51 1029 83.51 390 82.14

7888 Femur BHI 1029 83.51 1029 83.51 390 82.14

73850 4236 Humerus ROM 520 75.82 520 75.82 208 78.49 208 78.49

B 504 2010.45.103 Fibula TCM 823 83.08

6493 Fibula BHI 826 83.33

3214 Femur BHI 1041 84.54 1041 84.54 395 83.25

6265 Femur BHI 1041 84.54 1041 84.54 395 83.25

6444 Femur BHI 1041 84.54 1041 84.54 395 83.25

8938 Femur BHI 1041 84.54 1041 84.54 395 83.25

3695 Radius BHI 457 72.00

6577 Radius BHI 457 72.00

6596 Radius BHI 457 72.00

B 497 2010.45.100 Fibula TCM 829 83.69

6368 Humerus BHI 530 77.28 530 77.28 202 76.20

B 862 Femur TCM 1050 85.23 1050 85.23 399 84.00

3650 Ulna BHI 508 71.43

91-1104 Ulna BHI 508 71.43

6468 Tibia BHI 940 90.24 940 90.24 316 87.68

281

6104 Fibula BHI 838 84.62

6614 Fibula BHI 838 84.62

7664 Fibula BHI 838 84.62

7150 Humerus BHI 533 77.78 533 77.78 203 76.68

90-835 Humerus BHI 533 77.78 533 77.78 205 77.36

8796 Humerus BHI 533 77.78 533 77.78 205 77.40

5502 Humerus BHI 534 77.87 534 77.87 201 75.85 201 75.85

67792 8310 Femur ROM 1065 86.45 1065 86.45 410 86.39 410 86.39

91-0514 Femur BHI 1067 86.60 1067 86.60 406 85.47

B 689 Femur TCM 1070 86.86 1070 86.86 407 85.75

6592 Radius BHI 470 74.00

B 316 2009.71.58 Tibia TCM 960 92.18 960 92.18 322 92.05 322 89.44

B 327 2009.71.37 Humerus TCM 545 79.47 545 79.47 200 75.47 200 75.47

3564 Humerus BHI 545 79.47 545 79.47 208 78.34

91-0254 Tibia BHI 965 92.68 965 92.68 323 89.84

3124 Fibula BHI 864 87.18

3588 Fibula BHI 864 87.18

3014a Fibula BHI 864 87.18

1820 6601 Tibia UWGM 970 93.14 970 93.14 325 90.24

5427 Femur BHI 1092 88.66 1092 88.66 416 87.69

90-490 Femur BHI 1092 88.66 1092 88.66 416 87.69

90-514 Humerus BHI 552 80.56 552 80.56 210 79.41

3508 Radius BHI 483 76.00

4363 Radius BHI 483 76.00

7652 Radius BHI 483 76.00

8234 Radius BHI 483 76.00

4725 Ulna BHI 533 75.00

6342 Ulna BHI 533 75.00

6343 Ulna BHI 533 75.00

8423 Ulna BHI 533 75.00

7350 Femur BHI 1105 89.69 1105 89.69 421 88.81

3727 Humerus BHI 559 81.48 559 81.48 213 80.32

6620 Tibia BHI 991 95.12 991 95.12 331 91.99

282

91-0157 Tibia BHI 991 95.13 991 95.12 331 92.00

1822 7976 Femur UWGM 1111 90.19 1111 90.19 453 95.45 453 95.45

B 857 Tibia TCM 993 95.35 993 95.35 331 94.62 331 91.94

B 854 Femur TCM 1115 90.51 1115 90.51 426 89.69

1818 3477b Tibia UWGM 997 95.74 997 95.74 345 98.62 345 95.83

264 Femur BHI 1118 90.72 1118 90.72 427 89.92

5428 Fibula BHI 889 89.74

90-292 Fibula BHI 889 89.74

263 Tibia BHI 1000 96.02 1000 96.02 334 92.78

7256 Radius BHI 495 78.00

7820 Radius BHI 495 78.00

8280 Ulna BHI 546 76.79

90-194 Ulna BHI 546 76.79

7838 Fibula BHI 902 91.03

6279 Tibia BHI 1016 97.56 1016 97.56 339 94.14

8880 Tibia BHI 1016 97.57 1016 97.56 339 94.14

7490 Tibia BHI 1016 97.57 1016 97.56 339 94.15

B 859 2012.11.69 Fibula TCM 906 91.46

7180 Femur BHI 1143 92.78 1143 92.78 437 92.15

8233 Femur BHI 1143 92.78 1143 92.78 437 92.15

8802 Femur BHI 1143 92.78 1143 92.78 437 92.15

90-368 Femur BHI 1143 92.78 1143 92.78 437 92.15

Z8153 Femur BHI 1143 92.78 1143 92.78 437 92.15

B 194 2008.211.9 Ulna TCM 552 77.62

1817 3094 Femur UWGM 1144 92.86 1144 92.86 440 92.71 440 92.71

73853 91-0918 Tibia ROM 1025 98.43 1025 98.43 360 102.91 360 100.00

B 851 Femur TCM 1150 93.35 1150 93.35 440 92.77

90-459 Fibula BHI 914 92.31

Z8155 Tibia BHI 1029 98.78 1029 98.78 343 95.21

73852 8604 Tibia ROM 1030 98.91 1030 98.91 350 100.05 350 97.22

6439 Femur BHI 1156 93.81 1156 93.81 443 93.27

4615 Radius BHI 508 80.00

7591 Radius BHI 508 80.00

283

90-485 Radius BHI 508 80.00

7660 Ulna BHI 559 78.57

2106 Humerus BHI 584 85.19 584 85.19 222 83.95

8541 Humerus BHI 584 85.19 584 85.19 224 84.64

91-0325 Femur BHI 1162 94.33 1162 94.33 445 93.83

B 100 2007.207.98 Radius TCM 511

90-846 Fibula BHI 927 93.59

B 338 Humerus TCM 589 85.85 229 86.42 229 86.42

6621 Tibia BHI 1041 100.00 1041 100.00 347 96.28

8937 Tibia BHI 1042 100.01 1041 100.00 347 96.29

1313 Femur BHI 1168 94.85 1168 94.85 448 94.39

6491 Femur BHI 1168 94.85 1168 94.85 448 94.39

7409 Femur BHI 1168 94.85 1168 94.85 448 94.39

7975 Femur BHI 1168 94.85 1168 94.85 448 94.39

8545 Femur BHI 1168 94.85 1168 94.85 448 94.39

7466 Ulna BHI 566 79.64

B 335 Femur TCM 1173 95.22 1173 95.22 453 95.45 453 95.45

5392 Fibula BHI 935 94.39

B 934 Fibula TCM 937 94.59

207 Femur BHI 1180 95.79 1180 95.79 453 95.41

7217 Fibula BHI 940 94.87

91-0807 Ulna BHI 572 80.36

90-831 Femur BHI 1187 96.39 1187 96.39 456 96.07

3470 Fibula BHI 945 95.40

7086 Femur BHI 1194 96.91 1194 96.91 459 96.63

8855 Femur BHI 1194 96.91 1194 96.91 459 96.63

90-548 Humerus BHI 603 87.96 603 87.96 230 86.67

91-1397 Humerus BHI 603 87.96 603 87.96 232 87.36

B 499 2010.45.101 Fibula TCM 954 96.31

1091 Fibula BHI 957 96.61

4714 Ulna BHI 584 82.14

91-0725 Ulna BHI 584 82.14

5503 Fibula BHI 965 97.42

284

6441 Fibula BHI 965 97.44

5512 Radius BHI 533 84.00

7038 Radius BHI 533 84.00

90-293 Fibula BHI 975 98.43

B 456 2010.45.10 Fibula TCM 978 98.73

91-1496 Femur BHI 1232 100.00 1232 100.00 475 100.00

6100 Humerus BHI 622 90.74 622 90.74 237 89.39

5431 Fibula BHI 991 100.00

8723 Fibula BHI 991 100.00

3751 Humerus BHI 635 92.59 635 92.59 242 91.21

91-0592 Humerus BHI 635 92.59 635 92.59 243 91.74

6598 Humerus BHI 635 92.59 635 92.59 243 91.77

5379 Humerus BHI 635 92.59 635 92.59 243 91.85

6110 Humerus BHI 635 92.59 635 92.59 244 91.89

6184 Ulna BHI 610 85.71

8858 Ulna BHI 610 85.71

91-0459 Ulna BHI 610 85.71

6612 Humerus BHI 640 93.32 640 93.32 244 91.92

8178 Radius BHI 559 88.00

90-430 Ulna BHI 616 86.61

B 192 Radius TCM 561

B 192 Ulna TCM 621 87.32

67794 8994 Humerus ROM 650 94.78 650 94.78 240 90.57 240 90.57

90-140 Humerus BHI 650 94.78 650 94.78 247 93.35

B 258 2008.211.119 Radius TCM 567

Z8154 Radius BHI 572 90.00

6233 Humerus BHI 660 96.30 660 96.30 251 94.84

91-1375 Humerus BHI 660 96.30 660 96.30 253 95.36

91-0730 Humerus BHI 660 96.30 660 96.30 253 95.38

8485 Humerus BHI 660 96.30 660 96.30 253 95.45

6543 Ulna BHI 635 89.29

8047 Ulna BHI 635 89.29

1296 Humerus BHI 670 97.70 670 97.70 265 100.00 265 100.00

285

4145 Radius BHI 584 92.00

7811 Radius BHI 584 92.00

8309 Radius BHI 584 92.00

3084 Radius BHI 590 92.91

5136 Humerus BHI 680 99.15 680 99.15 259 97.64

8982 Humerus BHI 686 100.00 686 100.00 261 98.47

262 Radius BHI 600 94.49

6522 Ulna BHI 660 92.86

7810 Ulna BHI 660 92.86

7941 Ulna BHI 660 92.86

6064 Radius BHI 610 96.00

7494 Ulna BHI 673 94.64

7712 Ulna BHI 673 94.64

5393 Radius BHI 622 98.00

7661 Radius BHI 622 98.00

6496 Ulna BHI 686 96.43

8422 Ulna BHI 686 96.43

8941 Radius BHI 635 100.00

90-533 Ulna BHI 699 98.21

8800 Ulna BHI 711 100.00

91-1230 Ulna BHI 711 100.00