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Reptilia: Captorhinidae) and the Community Histology of the Early Permian Fissure-Fill Fauna Dolese Quarry, Richards Spur, Oklahoma

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Reptilia: Captorhinidae) and the Community Histology of the Early Permian Fissure-Fill Fauna Dolese Quarry, Richards Spur, Oklahoma The Ontogenetic Osteohistology of the Eureptile Captorhinus aguti (Reptilia: Captorhinidae) and the Community Histology of the Early Permian Fissure-Fill Fauna Dolese Quarry, Richards Spur, Oklahoma by Eilidh Jaine Richards A thesis submitted in conformity with the requirements for the degree of Master of Science Department of Ecology and Evolutionary Biology University of Toronto © Copyright by Eilidh Jaine Richards 2016 The Ontogenetic Osteohistology of the Eureptile Captorhinus aguti (Reptilia: Captorhinidae) and the Community Histology of the Early Permian Fissure-Fill Fauna Dolese Quarry, Richards Spur, Oklahoma Eilidh Jaine Richards Master of Science Department of Ecology and Evolutionary Biology University of Toronto 2016 Abstract Palaeohistological research has greatly enhanced our ability to draw conclusions about the physiology and growth of extinct vertebrates. A comprehensive histological growth study has never been undertaken in an Early Permian taxon at the initial stages of terrestrial vertebrate evolution. Captorhinus aguti, a common Early Permian eureptile from the fissure-fill locality near Richards Spur, Oklahoma, is the ideal taxon for a study of this type. C. aguti femora from all growth stages were measured and sectioned to compare bone structure through ontogeny. Representatives of other major taxa from the Richards Spur locality were also sectioned to compare histology across the palaeocommunity. Long bones of all sectioned Richards Spur taxa, including all growth stages of C. aguti, display slow growing parallel-fibered lamellar bone with poor vascularization. Captorhinids were the only taxon from this locality that lacked growth lines, implying that they were employing a different growth strategy from the other taxa that were preserved at this locality. ii Acknowledgments First I would like to thank my supervisors, Dr. Robert Reisz and Dr. David Evans, for pushing me to think and learn independently. I also extend my gratitude to the other members of my MSc supervisory committee, Dr. Mary Silcox and Dr. Denis Walsh, for their support and encouragement. A Canada Graduate Scholarship – Master’s Program – from the Natural Sciences and Engineering Research Council of Canada funded much of my research. Further financial funding was generously provided via the C.S. “Rufus” Churcher Graduate Scholarship in Ecology and Evolutionary Biology and the Frederick P. Ide Graduate Award in Ecology and Evolutionary Biology through the Department of Ecology and Evolutionary Biology at the University of Toronto. Dr. Kirstin Brink, Kentaro Chiba, and Aaron LeBlanc were instrumental in my instruction of proper histological practices, as well as 3D and microscope imaging. Diane Scott provided valuable advice for my scientific illustrations, and I also thank her for photographing all my specimens. Thanks to Dr. Richard Cifelli, William May, and the Sam Noble Oklahoma Natural History Museum for access to and permission to section many Richards Spur fossils. Thanks to Dr. Kevin Seymour for his aid in the Royal Ontario Museum (ROM) Paleontology Collections. Brian Iwama provided much technical support with the equipment in the histology laboratory at the ROM. Thoughtful discussions with my supervisors, Dr. Robert Reisz and Dr. David Evans, my MSc supervisory committee, Dr. Mary Silcox and Dr. Denis Walsh, and everyone else I worked with over the past few years including Dr. Kirstin Brink, Kentaro Chiba, Thomas Cullen, Jessica Hawthorn, Derek Larson, Aaron LeBlanc, Ian Macdonald, Mark MacDougall, Helen Rodd, Diane Scott, and Mateusz Wosik, were all key in my progress and completion of my MSc research. Special thanks goes to my biggest supporters, my parents, Sheila Zane and Dave Richards, for their endless support and encouragement over the years. And finally, thanks to Ian Macdonald for his continual reinforcement and natural inspiration. iii Table of Contents CHAPTER ONE: INTRODUCTION…………………………………………………………1 Literature Cited………………………………………………………………………………..6 CHAPTER TWO: THE ONTOGENETIC OSTEOHISTOLOGY OF THE EUREPTILE CAPTORHINUS AGUTI (REPTILIA: CAPTORHINIDAE)………………………………...11 Abstract……………………………………………………………………………………….11 Introduction…………………………………………………………………………………...12 Materials and Methods………………………………………………………………………..14 Results………………………………………………………………………………………...19 Discussion…………………………………………………………………………………….27 Acknowledgments…………………………………………………………………………….30 Literature Cited……………………………………………………………………………….31 CHAPTER THREE: COMMUNITY HISTOLOGY OF THE EARLY PERMIAN FISSURE- FILL LOCALITY DOLESE QUARRY, RICHARDS SPUR, OKLAHOMA.……………...37 Abstract……………………………………………………………………………………….37 Introduction…………………………………………………………………………………...38 Materials and Methods………………………………………………………………………..40 Results………………………………………………………………………………………...42 Discussion…………………………………………………………………………………….50 Acknowledgements…………………………………………………………………………...54 Literature Cited……………………………………………………………………………….55 APPENDIX 1…………………………………………………………………………………59 iv List of Tables Table 2-1: Reduced major axis regression analyses of the five femoral measurements of Captorhinus aguti relative to femur length…………………………………………………….19 Table 2-2: Osteocyte Lacunar Densities (OLDs) of Captorhinus aguti at a range of growth stages ………………………………………………………………………………………………….20 Table 3-1: Faunal list of sectioned specimens from the Early Permian fissure-fill deposits Dolese Brothers Quarry near Richards Spur, Oklahoma……………………………………………….40 Table 3-2: Lines of Arrested Growth observed in each of the sectioned fauna of the deposits of Dolese Brothers Quarry, Richards Spur………………………………………………………..48 Table 3-3: Osteocyte Lacunar Densities of sectioned fauna of the fissure-fill deposits of Dolese Quarry, near Richards Spur, Oklahoma………………………………………………………..49 Table 3-4: Summary of bone structure findings for the sectioned anamniote tetrapods, reptiles, and synapsids of the Dolese Quarry, Richards Spur…………………………………………..51 v List of Figures Figure 2-1: Line drawings of a Captorhinus aguti femur showing the six measurements that were recorded across twenty femora………………………………………………………………….15 Figure 2-2: Ventral views of the four representative femora at different growth stages………..17 Figure 2-3: The Osteocyte Lacunar Density (OLD) relative to anterior-posterior diameter at mid- diaphysis in Captorhinus aguti femora of a range of sizes……………………………………...21 Figure 2-4: Thin section images from the four Captorhinus aguti representative femora sizes...22 Figure 2-5: Thin section images from the three non-Richards Spur captorhinid femoral representatives……………………………………………………………………………………24 Figure 2-6: Thin section of an adult Captorhinus aguti maxilla with a close up view of the lines of von Ebner……………………………………………………………………………………...26 Figure 3-1: Line drawing of the approximate location of Richards Spur, Oklahoma, USA during the Early Permian………………………………………………………………………………...39 Figure 3-2: Mid-diaphyseal transverse sections of anamniote tetrapods from Dolese Quarry, Richards Spur…………………………………………………………………………………….43 Figure 3-3: Mid-diaphyseal transverse sections of eureptiles from Dolese Quarry, Richards Spur………………………………………………………………………………………………45 Figure 3-4: Mid-diaphyseal transverse sections of synapsids from Dolese Quarry, Richards Spur………………………………………………………………………………………………47 vi 1 Chapter 1 Introduction The Early Permian was a critical time in the evolution of the earliest terrestrial vertebrates. Just prior to the start of the Permian, anamniote tetrapods were joined by two other major tetrapod groups: eureptiles (including extant reptiles and birds), and synapsids (including extant mammals), and together these three major groups completed the invasion of equatorial terrestrial environments at the beginning of the Permian (Sumida and Martin, 1997). Early tetrapod diversification and evolution is of interest to evolutionary biologists because the adaptations in a group’s life history impact the trajectory of that group. Yet, not many studies focus on the growth and life history of these early terrestrial tetrapods. By understanding the mechanics behind the growth strategies in early terrestrial vertebrates, we will further be able to understand the evolution of growth strategies in vertebrates through time, and this is what I hope to achieve in my research. To accomplish this goal, a histological approach is used. Histology is the study of the structure of cells and tissues of organisms (Padian and Lamm, 2013). Specifically, bone histology – involving the sectioning and grinding down of bones until the microscopic structure of bone can be examined – is exceptionally useful in understanding the physiology (e. g. de Ricqlès, 1974; de Ricqlès, 1980), ecology (e.g. Cooper et al., 2008), and growth (e. g. Horner et al., 1999; Erickson and Tumanova, 2000) of extinct vertebrates, and is a popular approach used in palaeontology as a result. Due to extensive histological studies that have been performed with extant vertebrates (e.g. Enlow and Brown, 1956; 1957; 1958; Castanet et al., 2000; Köhler et al., 2012; Quémeneur et al., 2013), palaeontologists have a wide knowledge base in the literature to use as a basis of comparison when examining the microanatomy of fossil bone structure. Inferences that can be made about an animal’s physiology and life history from histological studies of fossils are numerous. For instance, the type of bone seen in cross-section can indicate whether the individual was immature or an adult at the time of its death, as well as its relative rate of growth based on the amount of remodeling and vascularization
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