DOCSLIB.ORG

Analysis of Hadrosaur Teeth from Egg Mountain Quarry, a Diffuse

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Analysis of Hadrosaur Teeth from Egg Mountain Quarry, a Diffuse ANALYSIS OF HADROSAUR TEETH FROM EGG MOUNTAIN QUARRY, A DIFFUSE MICROSITE LOCALITY, UPPER CRETACEOUS, TWO MEDICINE FORMATION, NORTHWEST MONTANA by Garrett Benson Scofield A thesis submitted in partial fulfillment for the requirements of the degree of Masters of Science in Paleontology MONTANA STATE UNIVERSITY Bozeman, Montana April 2018 ©COPYRIGHT by Garrett Benson Scofield 2018 All Rights Reserved ii ACKNOWLEDGEMENTS I would like to extend my deepest thanks first and foremost to Dave Varricchio, my fellow grad students, and the Earth Sciences of Montana State University for helping to make this possible. Dave’s quiet but sound advice, Chis Organ and his unquenched desire for solid analysis, and the “Dino Dentist”, Greg Erickson made for an excellent committee. Secondly, without the support of my second half, Kandice Magnuson, and my family I likely would not be who or where I am today; nor would this thesis have come to be. Thank you. Thanks should be extended to the Museum of the Rockies and Ellen- Therese Lamm for her boundless desire to educate us in the histological method and for her generosity in the use of MOR facilities. Dave Trexler and the Two Medicine Dinosaur Center also deserve thanks for a warm welcome and allowing me to look through their collections. Special thanks go to Dave Varricchio and the National Research Foundation (NSF (EAR) grant nos. 0847777 and 1325674 to D.J.V.) as well as the generosity of Dr. Karolyn Hoo, and the Graduate School for the financial assistance with grad school and this project. Finally, I would like to thank the Beatrice R. Taylor Paleontological Research Area and the 2010-2015 Egg Mt. Field Crew for the abundance of teeth. iii TABLE OF CONTENTS 1. INTRODUCTION ..........................................................................................................1 Previous Work/Background ....................................................................................5 2. MATERIALS AND METHODS .................................................................................. 17 Geologic Setting.................................................................................................... 17 Two Medicine Formation ......................................................................... 17 Willow Creek Anticline ............................................................................ 18 Locality ..................................................................................................... 19 Methods................................................................................................................. 21 Preparation ................................................................................................ 22 Measurement ............................................................................................. 23 Condition and Size -Frequency Analysis .................................................. 24 Examination of Museum Collections........................................................ 25 Histological Examination of Egg Mt. Hadrosaur Teeth ........................... 28 Determination of Shedding Quotient ........................................................ 31 Determination of Disarticulation Quotient ............................................... 33 Conversion and Representation of Mortality ............................................ 35 Life Table and Survivorship ..................................................................... 35 3. RESULTS ..................................................................................................................... 37 Shedding Consideration and Calculation of Shedding Quotient .......................... 37 Disarticulation Consideration and Calculation of Disarticualtion Quotient................................................................................................................. 44 Tooth Size to Body Size Correlation .................................................................... 46 Egg Mt. Assemblage ............................................................................................. 48 Application of the SQ to the Egg Mt. Assemblage ............................................... 56 Application of the DQ to the Egg Mt. Assemblage .............................................. 58 Maiasaura Mortality and Survivorship ................................................................ 59 Raw Tooth Size Represented as Population ............................................. 59 Shedding Quotient Population Representation ......................................... 61 Disarticulation Quotient Population Representation ................................ 61 4. DISCUSSION ............................................................................................................... 70 Taphonomic Interpretation of the Egg Mt. Assemblage ....................................... 70 Interpretation of Mortality .................................................................................... 76 Interpretation of Methods ..................................................................................... 78 Measurement ............................................................................................. 78 Tooth Growth and Shedding Rates ........................................................... 80 iv TABLE OF CONTENTS CONTINUED Species Identification ................................................................................ 81 Shedding and Disarticulation Quotients ................................................... 82 Mortality and Survivorship ....................................................................... 84 5. SUMMARY AND CONCLUSION ............................................................................. 88 REFERENCES ................................................................................................................. 92 APPENDICES .................................................................................................................102 APPENDIX A: Measured Egg Mt. Specimens...................................................103 APPENDIX B: von Ebner Line and Dentine Thickness Measurements ...........................................................................107 APPENDIX C: Examined Museum Specimens .................................................112 APPENDIX D: Scaled Tooth Size and Population Distributions .......................115 APPENDIX E: Extra Specimen Data and Graphs ..............................................123 v LIST OF TABLES Tables Page 1. List of sectioned teeth and associated measurements .........................................30 2. Proportions of hadrosaur and theropod teeth in the Egg Mt. sample .................................................................................................................54 3. Life table of Maiasaura Based on Raw Data......................................................63 4. Life table of Maiasaura Based on Shedding Quotient .......................................64 5. Life table of Maiasaura Based on Disarticulation Quotient ...............................65 A.1. von Ebner and Dentine Thickness Measurements ............................................ 104 A.2. Measured Egg Mountain Specimens ................................................................ 108 A.3. Measured MOR Specimens .............................................................................. 113 vi LIST OF FIGURES Figures Page 1. Examples of past population studies ...................................................................16 2. Upper Cretaceous sediments and geologic context of the field area ..................18 3. Tooth measurement index ...................................................................................24 4. Ontogenetic growth stages for Maiasaura ..........................................................28 5. Flow chart of methods ........................................................................................36 6. Number of tooth families plotted against AP tooth size .....................................38 7. Tooth formation rates and shedding rates for sectioned Egg Mt. teeth ....................................................................................................................41 8. Sectioned Egg Mt. teeth and estimated growth stages ........................................43 9. Number of teeth within each tooth family and number of tooth families plotted against AP tooth dimensions ....................................................45 10. Estimated body size plotted against AP tooth dimensions .................................46 11. Size -frequency distribution of Maiasaura assemblage .....................................50 12. Egg Mt. Maiasaura teeth ...................................................................................51 13. Egg Mt. theropod teeth .......................................................................................52 14. Size-frequency of theropod teeth .......................................................................55 15. Size-frequency of Maiasaura population after applying SQ .............................57 16. Estimated APW tooth size-frequency ..................................................................58 17. Size-frequency distribution of Maiasaura teeth and estimated distribution of individuals after application of the DQ. .....................................60 18. Survivorship curve for Maiasaura based on raw data .......................................63 19. Survivorship
Load more

Recommended publications
  • Ontogeny Reveals Function and Evolution of the Hadrosaurid Dinosaur Dental Battery Aaron R
    LeBlanc et al. BMC Evolutionary Biology (2016) 16:152 DOI 10.1186/s12862-016-0721-1 RESEARCH ARTICLE Open Access Ontogeny reveals function and evolution of the hadrosaurid dinosaur dental battery Aaron R. H. LeBlanc1*, Robert R. Reisz1,2, David C. Evans3 and Alida M. Bailleul4 Abstract Background: Hadrosaurid dinosaurs, dominant Late Cretaceous herbivores, possessed complex dental batteries with up to 300 teeth in each jaw ramus. Despite extensive interest in the adaptive significance of the dental battery, surprisingly little is known about how the battery evolved from the ancestral dinosaurian dentition, or how it functioned in the living organism. We undertook the first comprehensive, tissue-level study of dental ontogeny in hadrosaurids using several intact maxillary and dentary batteries and compared them to sections of other archosaurs and mammals. We used these comparisons to pinpoint shifts in the ancestral reptilian pattern of tooth ontogeny that allowed hadrosaurids to form complex dental batteries. Results: Comparisons of hadrosaurid dental ontogeny with that of other amniotes reveals that the ability to halt normal tooth replacement and functionalize the tooth root into the occlusal surface was key to the evolution of dental batteries. The retention of older generations of teeth was driven by acceleration in the timing and rate of dental tissue formation. The hadrosaurid dental battery is a highly modified form of the typical dinosaurian gomphosis with a unique tooth-to-tooth attachment that permitted constant and perfectly timed tooth eruption along the whole battery. Conclusions: We demonstrate that each battery was a highly dynamic, integrated matrix of living replacement and, remarkably, dead grinding teeth connected by a network of ligaments that permitted fine scale flexibility within the battery.
    [Show full text]
  • Theropod Teeth from the Upper Maastrichtian Hell Creek Formation “Sue” Quarry: New Morphotypes and Faunal Comparisons
    Theropod teeth from the upper Maastrichtian Hell Creek Formation “Sue” Quarry: New morphotypes and faunal comparisons TERRY A. GATES, LINDSAY E. ZANNO, and PETER J. MAKOVICKY Gates, T.A., Zanno, L.E., and Makovicky, P.J. 2015. Theropod teeth from the upper Maastrichtian Hell Creek Formation “Sue” Quarry: New morphotypes and faunal comparisons. Acta Palaeontologica Polonica 60 (1): 131–139. Isolated teeth from vertebrate microfossil localities often provide unique information on the biodiversity of ancient ecosystems that might otherwise remain unrecognized. Microfossil sampling is a particularly valuable tool for doc- umenting taxa that are poorly represented in macrofossil surveys due to small body size, fragile skeletal structure, or relatively low ecosystem abundance. Because biodiversity patterns in the late Maastrichtian of North American are the primary data for a broad array of studies regarding non-avian dinosaur extinction in the terminal Cretaceous, intensive sampling on multiple scales is critical to understanding the nature of this event. We address theropod biodiversity in the Maastrichtian by examining teeth collected from the Hell Creek Formation locality that yielded FMNH PR 2081 (the Tyrannosaurus rex specimen “Sue”). Eight morphotypes (three previously undocumented) are identified in the sample, representing Tyrannosauridae, Dromaeosauridae, Troodontidae, and Avialae. Noticeably absent are teeth attributed to the morphotypes Richardoestesia and Paronychodon. Morphometric comparison to dromaeosaurid teeth from multiple Hell Creek and Lance formations microsites reveals two unique dromaeosaurid morphotypes bearing finer distal denticles than present on teeth of similar size, and also differences in crown shape in at least one of these. These findings suggest more dromaeosaurid taxa, and a higher Maastrichtian biodiversity, than previously appreciated.
    [Show full text]
  • Dinosaur Gallery Explorer’S Notebook
    Dinosaur Gallery Explorer’s Notebook Name: Class: Level 3 © Museum of Natural Sciences Education Service 2012 29, Rue Vautier, 1000 Brussels. Tel: +32 (0)2 627 42 52 [email protected] www.sciencesnaturelles.be 1 Dinosaur Gallery - Level 3 Plan of the Gallery Each time you see a number in the margin of this notebook you must move to a new place in the gallery. Find where you are on the plan. entrance via mezzanine (level 0) stairs down to level -2 stairs up to level -1 The numbers on the plan correspond to the different stages on the dinosaur gallery. The numbers start on page 6 of this notebook Make sure you have a sharp pencil and a rubber with you! Make a team of three to answer the questions. 2 Dinosaur Gallery - Level 3 Before your visit... The first pages of this notebook will help you prepare for your visit to the museum! * Words followed by an asterisk are explained in the glossary on the last page. What is a dinosaur? Below are some characteristics of dinosaurs feet underneath their bodies 4 feet terrestrial eggs with shells vertebrate* ATTENTION Dinosaurs were terrestrial animals. At the same time, sea reptiles and flying reptiles lived on the Earth, but these animals were NOT dinosaurs! Herbivore or carnivore? To know whether a dinosaur ate meat or plants, take a look at its teeth herbivore carnivore When a dinosaur was a When a dinosaur was a herbivore, its teeth had flat ends, carnivore, its teeth had pointed like the prongs of a rake or like ends, like knives.
    [Show full text]
  • A Revised Taxonomy of the Iguanodont Dinosaur Genera and Species
    ARTICLE IN PRESS + MODEL Cretaceous Research xx (2007) 1e25 www.elsevier.com/locate/CretRes A revised taxonomy of the iguanodont dinosaur genera and species Gregory S. Paul 3109 North Calvert Station, Side Apartment, Baltimore, MD 21218-3807, USA Received 20 April 2006; accepted in revised form 27 April 2007 Abstract Criteria for designating dinosaur genera are inconsistent; some very similar species are highly split at the generic level, other anatomically disparate species are united at the same rank. Since the mid-1800s the classic genus Iguanodon has become a taxonomic grab-bag containing species spanning most of the Early Cretaceous of the northern hemisphere. Recently the genus was radically redesignated when the type was shifted from nondiagnostic English Valanginian teeth to a complete skull and skeleton of the heavily built, semi-quadrupedal I. bernissartensis from much younger Belgian sediments, even though the latter is very different in form from the gracile skeletal remains described by Mantell. Currently, iguanodont remains from Europe are usually assigned to either robust I. bernissartensis or gracile I. atherfieldensis, regardless of lo- cation or stage. A stratigraphic analysis is combined with a character census that shows the European iguanodonts are markedly more morpho- logically divergent than other dinosaur genera, and some appear phylogenetically more derived than others. Two new genera and a new species have been or are named for the gracile iguanodonts of the Wealden Supergroup; strongly bipedal Mantellisaurus atherfieldensis Paul (2006. Turning the old into the new: a separate genus for the gracile iguanodont from the Wealden of England. In: Carpenter, K. (Ed.), Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs.
    [Show full text]
  • 71St Annual Meeting Society of Vertebrate Paleontology Paris Las Vegas Las Vegas, Nevada, USA November 2 – 5, 2011 SESSION CONCURRENT SESSION CONCURRENT
    ISSN 1937-2809 online Journal of Supplement to the November 2011 Vertebrate Paleontology Vertebrate Society of Vertebrate Paleontology Society of Vertebrate 71st Annual Meeting Paleontology Society of Vertebrate Las Vegas Paris Nevada, USA Las Vegas, November 2 – 5, 2011 Program and Abstracts Society of Vertebrate Paleontology 71st Annual Meeting Program and Abstracts COMMITTEE MEETING ROOM POSTER SESSION/ CONCURRENT CONCURRENT SESSION EXHIBITS SESSION COMMITTEE MEETING ROOMS AUCTION EVENT REGISTRATION, CONCURRENT MERCHANDISE SESSION LOUNGE, EDUCATION & OUTREACH SPEAKER READY COMMITTEE MEETING POSTER SESSION ROOM ROOM SOCIETY OF VERTEBRATE PALEONTOLOGY ABSTRACTS OF PAPERS SEVENTY-FIRST ANNUAL MEETING PARIS LAS VEGAS HOTEL LAS VEGAS, NV, USA NOVEMBER 2–5, 2011 HOST COMMITTEE Stephen Rowland, Co-Chair; Aubrey Bonde, Co-Chair; Joshua Bonde; David Elliott; Lee Hall; Jerry Harris; Andrew Milner; Eric Roberts EXECUTIVE COMMITTEE Philip Currie, President; Blaire Van Valkenburgh, Past President; Catherine Forster, Vice President; Christopher Bell, Secretary; Ted Vlamis, Treasurer; Julia Clarke, Member at Large; Kristina Curry Rogers, Member at Large; Lars Werdelin, Member at Large SYMPOSIUM CONVENORS Roger B.J. Benson, Richard J. Butler, Nadia B. Fröbisch, Hans C.E. Larsson, Mark A. Loewen, Philip D. Mannion, Jim I. Mead, Eric M. Roberts, Scott D. Sampson, Eric D. Scott, Kathleen Springer PROGRAM COMMITTEE Jonathan Bloch, Co-Chair; Anjali Goswami, Co-Chair; Jason Anderson; Paul Barrett; Brian Beatty; Kerin Claeson; Kristina Curry Rogers; Ted Daeschler; David Evans; David Fox; Nadia B. Fröbisch; Christian Kammerer; Johannes Müller; Emily Rayfield; William Sanders; Bruce Shockey; Mary Silcox; Michelle Stocker; Rebecca Terry November 2011—PROGRAM AND ABSTRACTS 1 Members and Friends of the Society of Vertebrate Paleontology, The Host Committee cordially welcomes you to the 71st Annual Meeting of the Society of Vertebrate Paleontology in Las Vegas.
    [Show full text]
  • A Troodontid Dinosaur from the Latest Cretaceous of India
    ARTICLE Received 14 Dec 2012 | Accepted 7 Mar 2013 | Published 16 Apr 2013 DOI: 10.1038/ncomms2716 A troodontid dinosaur from the latest Cretaceous of India A. Goswami1,2, G.V.R. Prasad3, O. Verma4, J.J. Flynn5 & R.B.J. Benson6 Troodontid dinosaurs share a close ancestry with birds and were distributed widely across Laurasia during the Cretaceous. Hundreds of occurrences of troodontid bones, and their highly distinctive teeth, are known from North America, Europe and Asia. Thus far, however, they remain unknown from Gondwanan landmasses. Here we report the discovery of a troodontid tooth from the uppermost Cretaceous Kallamedu Formation in the Cauvery Basin of South India. This is the first Gondwanan record for troodontids, extending their geographic range by nearly 10,000 km, and representing the first confirmed non-avian tetanuran dinosaur from the Indian subcontinent. This small-bodied maniraptoran dinosaur is an unexpected and distinctly ‘Laurasian’ component of an otherwise typical ‘Gondwanan’ tetrapod assemblage, including notosuchian crocodiles, abelisauroid dinosaurs and gondwanathere mammals. This discovery raises the question of whether troodontids dispersed to India from Laurasia in the Late Cretaceous, or whether a broader Gondwanan distribution of troodontids remains to be discovered. 1 Department of Genetics, Evolution, and Environment, University College London, London WC1E 6BT, UK. 2 Department of Earth Sciences, University College London, London WC1E 6BT, UK. 3 Department of Geology, Centre for Advanced Studies, University of Delhi, New Delhi 110 007, India. 4 Geology Discipline Group, School of Sciences, Indira Gandhi National Open University, New Delhi 110 068, India. 5 Division of Paleontology and Richard Gilder Graduate School, American Museum of Natural History, New York, New York 10024, USA.
    [Show full text]
  • Evidence for a Tyrannosaurus Rex from Southeastern Colorado
    Evidence for aTyrannosaurus rex from southeastern Colorado Keith Berry, Platte Valley School District Re-7, Science Department, Kersey, Colorado 80644, and Frontiers of Science Institute, Mathematics and Science Teaching Institute, University of Northern Colorado, Greeley, Colorado 80369, [email protected] Discovery Femur: A limb bone fragment (TSJC racy of ± 0.5 mm along a radial transect, T. 2008.1.2) is also tentatively identified as cf. rex annual growth markers are exception- Dinosaur tooth and bone fragments were T. rex. Theropod bones commonly exhibit ally good predictors for the growth lines recovered from private property at an onion-skin layering in cross section (K. observed in this bone (cχ2 = 1.44, df = 6, undisclosed locality in southeastern Colo- Carpenter, pers. comm. 2007), and this p-value > 0.95). As T. rex is the only animal rado. The site is in an unnamed, transitional bone seems to lack this feature, although known to exhibit this characteristic pattern member of the uppermost Pierre Shale and the bone has distinct, differentiable layers. of growth (Erickson et al. 2004; Chinsamy- is likely within the Baculites eliasi ammonite Whereas the bone itself may not be exclu- Turan 2005), this is believed to be a fairly zone (N. Larson, pers. comm. 2007), mak- sively attributed to a theropod based on its powerful diagnostic test. ing the site early Maastrichtian. This is the gross histological properties alone, there are Significance—Estimated to be about 71 first record of dinosaur fossils from these quantitative reasons supporting this diag- m.y. old based on the age of the Baculites strata.
    [Show full text]
  • Phylogeny and Biogeography of Iguanodontian Dinosaurs, with Implications from Ontogeny and an Examination of the Function of the Fused Carpal-Digit I Complex
    Phylogeny and Biogeography of Iguanodontian Dinosaurs, with Implications from Ontogeny and an Examination of the Function of the Fused Carpal-Digit I Complex By Karen E. Poole B.A. in Geology, May 2004, University of Pennsylvania M.A. in Earth and Planetary Sciences, August 2008, Washington University in St. Louis A Dissertation submitted to The Faculty of The Columbian College of Arts and Sciences of The George Washington University in partial fulfillment of the requirements for the degree of Doctor of Philosophy August 31, 2015 Dissertation Directed by Catherine Forster Professor of Biology The Columbian College of Arts and Sciences of The George Washington University certifies that Karen Poole has passed the Final Examination for the degree of Doctor of Philosophy as of August 10th, 2015. This is the final and approved form of the dissertation. Phylogeny and Biogeography of Iguanodontian Dinosaurs, with Implications from Ontogeny and an Examination of the Function of the Fused Carpal-Digit I Complex Karen E. Poole Dissertation Research Committee: Catherine A. Forster, Professor of Biology, Dissertation Director James M. Clark, Ronald Weintraub Professor of Biology, Committee Member R. Alexander Pyron, Robert F. Griggs Assistant Professor of Biology, Committee Member ii © Copyright 2015 by Karen Poole All rights reserved iii Dedication To Joseph Theis, for his unending support, and for always reminding me what matters most in life. To my parents, who have always encouraged me to pursue my dreams, even those they didn’t understand. iv Acknowledgements First, a heartfelt thank you is due to my advisor, Cathy Forster, for giving me free reign in this dissertation, but always providing valuable commentary on any piece of writing I sent her, no matter how messy.
    [Show full text]
  • Dinosaur Eggshells from the Lower Maastrichtian St. Mary River Formation of Southern Alberta, Canada
    Canadian Journal of Earth Sciences Dinosaur eggshells from the lower Maastrichtian St. Mary River Formation of southern Alberta, Canada Journal: Canadian Journal of Earth Sciences Manuscript ID cjes-2017-0195.R1 Manuscript Type: Article Date Submitted by the Author: 13-Nov-2017 Complete List of Authors: Voris, Jared; University of Calgary, Geoscience; Zelenitsky, Darla; Department of Geoscience, Tanaka, Kohei; Nagoya Daigaku Hakubutsukan; University of Calgary, DepartmentDraft of Geoscience Therrien, François; Royal Tyrrell Museum of Palaeontology, Is the invited manuscript for consideration in a Special N/A Issue? : Keyword: eggshell, dinosaur, Cretaceous, Maastrichtian, Alberta https://mc06.manuscriptcentral.com/cjes-pubs Page 1 of 47 Canadian Journal of Earth Sciences 1 2 3 4 5 6 7 8 9 Dinosaur eggshells from the lower Maastrichtian St. Mary River Formation of southern 10 Alberta, Canada 11 12 Jared T. Voris, Darla K. Zelenitsky,Draft François Therrien, Kohei Tanaka 13 J. T. Voris, D. K. Zelenitsky, and K. Tanaka. Department of Geoscience, University of 14 Calgary, 2500 University Dr. NW, Calgary, AB T2N 1N4, Canada; [email protected], 15 [email protected], [email protected] 16 K. Tanaka. Nagoya University Museum, Nagoya University Furocho, Chikusa-Ku, Nagoya, 17 464-8601, Japan; [email protected] 18 F. Therrien. Royal Tyrrell Museum of Palaeontology, Box 7500, Drumheller, AB T0J 0Y0, 19 Canada.; [email protected] 20 1 https://mc06.manuscriptcentral.com/cjes-pubs Canadian Journal of Earth Sciences Page 2 of 47 1 2 Abstract–North America is known for its rich uppermost Cretaceous record of dinosaur egg 3 remains, although a notable fossil gap exists during the lower Maastrichtian.
    [Show full text]
  • Dinosaur Incubation Periods Directly Determined from Growth-Line Counts in Embryonic Teeth Show Reptilian-Grade Development
    Dinosaur incubation periods directly determined from growth-line counts in embryonic teeth show reptilian-grade development Gregory M. Ericksona,1, Darla K. Zelenitskyb, David Ian Kaya, and Mark A. Norellc aDepartment of Biological Science, Florida State University, Tallahassee, FL 32306-4295; bDepartment of Geoscience, University of Calgary, Calgary, AB, Canada T2N 1N4; and cDivision of Paleontology, American Museum of Natural History, New York, NY 10024 Edited by Neil H. Shubin, University of Chicago, Chicago, IL, and approved December 1, 2016 (received for review August 17, 2016) Birds stand out from other egg-laying amniotes by producing anatomical, behavioral and eggshell attributes of birds related to relatively small numbers of large eggs with very short incubation reproduction [e.g., medullary bone (32), brooding (33–36), egg- periods (average 11–85 d). This aspect promotes high survivorship shell with multiple structural layers (37, 38), pigmented eggs (39), by limiting exposure to predation and environmental perturba- asymmetric eggs (19, 40, 41), and monoautochronic egg pro- tion, allows for larger more fit young, and facilitates rapid attain- duction (19, 40)] trace back to their dinosaurian ancestry (42). For ment of adult size. Birds are living dinosaurs; their rapid development such reasons, rapid avian incubation has generally been assumed has been considered to reflect the primitive dinosaurian condition. throughout Dinosauria (43–45). Here, nonavian dinosaurian incubation periods in both small and Incubation period estimates using regressions of typical avian large ornithischian taxa are empirically determined through growth- values relative to egg mass range from 45 to 80 d across the line counts in embryonic teeth.
    [Show full text]
  • Competition Structured a Late Cretaceous Megaherbivorous Dinosaur Assemblage Jordan C
    www.nature.com/scientificreports OPEN Competition structured a Late Cretaceous megaherbivorous dinosaur assemblage Jordan C. Mallon 1,2 Modern megaherbivore community richness is limited by bottom-up controls, such as resource limitation and resultant dietary competition. However, the extent to which these same controls impacted the richness of fossil megaherbivore communities is poorly understood. The present study investigates the matter with reference to the megaherbivorous dinosaur assemblage from the middle to upper Campanian Dinosaur Park Formation of Alberta, Canada. Using a meta-analysis of 21 ecomorphological variables measured across 14 genera, contemporaneous taxa are demonstrably well-separated in ecomorphospace at the family/subfamily level. Moreover, this pattern is persistent through the approximately 1.5 Myr timespan of the formation, despite continual species turnover, indicative of underlying structural principles imposed by long-term ecological competition. After considering the implications of ecomorphology for megaherbivorous dinosaur diet, it is concluded that competition structured comparable megaherbivorous dinosaur communities throughout the Late Cretaceous of western North America. Te question of which mechanisms regulate species coexistence is fundamental to understanding the evolution of biodiversity1. Te standing diversity (richness) of extant megaherbivore (herbivores weighing ≥1,000 kg) com- munities appears to be mainly regulated by bottom-up controls2–4 as these animals are virtually invulnerable to top-down down processes (e.g., predation) when fully grown. Tus, while the young may occasionally succumb to predation, fully-grown African elephants (Loxodonta africana), rhinoceroses (Ceratotherium simum and Diceros bicornis), hippopotamuses (Hippopotamus amphibius), and girafes (Girafa camelopardalis) are rarely targeted by predators, and ofen show indiference to their presence in the wild5.
    [Show full text]
  • Saurolophus Angustirostris (Dinosauria: Hadrosauridae), from the Upper Cretaceous of Mongolia
    RESEARCH ARTICLE Perinatal Specimens of Saurolophus angustirostris (Dinosauria: Hadrosauridae), from the Upper Cretaceous of Mongolia Leonard Dewaele1,2*, Khishigjav Tsogtbaatar3, Rinchen Barsbold3, Géraldine Garcia4, Koen Stein5, François Escuillié6, Pascal Godefroit1 1 Directorate 'Earth and History of Life', Royal Belgian Institute of Natural Sciences, rue Vautier 29, B-1000, Brussels, Belgium, 2 Research Unit Palaeontology, Department Geology and Soil Sciences, Ghent University, Krijgslaan 281, 9000, Ghent, Belgium, 3 Institute of Paleontology and Geology, Mongolian Academy of Sciences, Ulaanbaatar, 210–351, Mongolia, 4 Université de Poitiers, IPHEP, UMR CNRS 7262, 6 rue M. Brunet, 86073, Poitiers cedex 9, France, 5 Earth System Science, AMGC, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium, 6 Eldonia, 9 Avenue des Portes Occitanes, 3800, Gannat, France * [email protected] OPEN ACCESS Abstract Citation: Dewaele L, Tsogtbaatar K, Barsbold R, Garcia G, Stein K, Escuillié F, et al. (2015) Perinatal Specimens of Saurolophus angustirostris Background (Dinosauria: Hadrosauridae), from the Upper The Late Cretaceous Nemegt Formation, Gobi Desert, Mongolia has already yielded abun- Cretaceous of Mongolia. PLoS ONE 10(10): dant and complete skeletons of the hadrosaur Saurolophus angustirostris, from half-grown e0138806. doi:10.1371/journal.pone.0138806 to adult individuals. Editor: Andrew A. Farke, Raymond M. Alf Museum of Paleontology, UNITED STATES Received: April 22, 2015 Methodology/Principal Findings Accepted: September 3, 2015 Herein we describe perinatal specimens of Saurolophus angustirostris, associated with fragmentary eggshell fragments. The skull length of these babies is around 5% that of the Published: October 14, 2015 largest known S. angustirostris specimens, so these specimens document the earliest Copyright: © 2015 Dewaele et al.
    [Show full text]