Assessing Acrodont Dentition in Reptilia, with Special Attention to Replacement and Wear Adaptations by Yara Haridy 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 Yara Haridy 2018 Assessing Acrodont Dentition in Reptilia, with special Attention to Replacement as and Wear Adaptations Yara Haridy Master of Science Department of Ecology and Evolutionary Biology University of Toronto 2018 Abstract Tooth implantation has been conflated with other tooth characteristics, such as replacement, attachment, and morphology. Tooth attachment refers to the tissues that attach teeth, whilst implantation refers to the orientation of the tooth relative to the jaw. There are three main forms of tooth implantation identified in Reptilia: (1) thecodonty, where the tooth in implanted in a socket, (2) pleurodonty, the tooth is implanted against the side of the jaw, and (3) acrodonty the tooth is at the apex of the jaw; this thesis is concerned with the latter. Acrodonty has long been linked with a lack of replacement, which is because all modern acrodont reptiles do not replace their teeth; instead, they exhibit derived wear adaptations that help them counteract the loss of replacement. Here in this study, I explore the wear adaptations in extant acrodont reptiles, and analyze forms of acrodonty found within Reptilia in the Permian. ii Acknowledgments It has been quite the transition from an undergraduate heading to veterinary college, to the word of academia and paleontology. It would have been impossible to make this leap without the supportive community at University of Toronto Mississauga, I could not have found this path nor completed this thesis without everyone’s help, so I sincerely hope I do not forget anyone. Firstly, I would like to thank my supervisor Professor Robert Reisz, for initially taking me into his lab when I was a lost undergraduate looking to learn anatomy. I would like to especially thank him for putting up with my incessant questioning, stubbornness, and would like to acknowledge all the opportunities he has provided me that have fed and fueled my curiosity. I would like to extend a special thanks to Diane Scott, whom vouched for me when I first came into the lab with no previous knowledge of paleontology, she fostered my growing curiosity and answered every question I threw her way without fail. She is a consistent and unwavering pillar of support that is the hallmark of the Reisz lab experience. I would like to thank her for all her support over these years, and for all the endless knowledge she enthusiastically shared, from fossil preparation to scientific illustration. I would like to thank my supervisory committee for their assistance in the direction of these studies. Professor David Evans of the Royal Ontario Museum was a great help with his consistently innovative ideas, and for full access to the Paleohistology lab at the ROM. Professor Luke Mahler who’s extensive knowledge on all things reptilian aided in these studies. I would extend thanks to Dr. Aaron LeBlanc and Dr. Mark MacDougall, the two of which provided endless entertainment and support in the Reisz lab. Mark put up with me through my first ever publication as an undergrad, and Aaron co-designed the main questions that I addressed in my thesis, and taught me all I know about histology, a skill that I will continue to include in my future work. Aaron and Mark have taught me so much about being a diligent scientist I could not be more thankful for having them as senior students while completing my degree. I would like to extend a special thank you to Bryan Gee, for putting up with my constant attitude, for his valiant attempt at teaching me about amphibians, for being my diligent copy editor, and for being a friend. I would thank Professor Dave Mazierski for teaching me about scientific illustration and for patiently designing the developmental model in chapter 3. iii A huge thank you to Kevin Seymor who let me scour the collections at the ROM and allowed me to pick and choose from his precious collection to complete my studies, without his endless knowledge on all things living and dead these studies may not have come to fruition. The graduate students, and supports staff at the ROM always made for a welcoming and intellectually stimulating environment, and for that I am thankful. Finally, I would like to thank my immediate family. My mother Sherine Hafez, and grandmother Nadia El-Enany, without these two strong stubborn women in my life I would not be who I am today. They taught me the value of tenacity, and supported every turn my life took, I could not wish for better role models. I would like to thank my brother Youssef, who made me endless coffees on late nights and took care of my sanity. It takes an immense support network to be successful and happy in life, and I do not take mine for granted. iv Table of Contents Acknowledgements ........................................................................................................................ iii Table of Contents .............................................................................................................................v List of Figures ................................................................................................................................ ix Chapter 1 Histological analysis of post-eruption tooth wear adaptations, and ontogenetic changes in tooth implantation in the acrodontan squamate Pogona vitticeps .............................1 Introduction .................................................................................................................................1 Materials and Methods ................................................................................................................2 2.1 Histology ..............................................................................................................................3 2.2 Confounding factors.............................................................................................................3 Results .........................................................................................................................................4 3.1 External anatomy .................................................................................................................4 3.2 Histology ..............................................................................................................................6 Discussion .................................................................................................................................18 Conclusion ................................................................................................................................22 Literature Cited .........................................................................................................................23 Chapter 2 Histology of the coronoid dentition with evidence of replacement in the Permian parareptile Delorhynchus ..........................................................................................................32 Abstract .....................................................................................................................................32 Introduction ...............................................................................................................................33 Materials and Methods ..............................................................................................................34 Results .......................................................................................................................................35 10.1.1 Mandible ................................................................................................................35 10.1.2 Coronoids ...............................................................................................................43 10.1.3 Dentition ................................................................................................................44 10.1.4 Histology ................................................................................................................45 Discussion .................................................................................................................................48 v 11.1 Multiple coronoids and coronoid dentition among Palaeozoic reptiles .............................48 11.2 Taxonomic status of Bolterpeton carrolli ..........................................................................53 Conclusions ...............................................................................................................................55 Literature Cited .........................................................................................................................56 Chapter 3 Opisthodontosaurus as a model for acrodont tooth replacement and dental ontogeny . ..................................................................................................................................60 Abstract .....................................................................................................................................60 Introduction ...............................................................................................................................61 Materials and methods ..............................................................................................................62