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The Evolution and Function of Theropod Dinosaur Tails

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The Evolution and Function of Theropod Dinosaur Tails University of Alberta The Evolution and Function of Theropod Dinosaur Tails by Walter Scott Persons A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Systematics and Evolution Department of Biological Sciences ©Walter Scott Persons Fall 2011 Edmonton, Alberta Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission. Library and Archives Bibliotheque et Canada Archives Canada Published Heritage Direction du 1+1 Branch Patrimoine de I'edition 395 Wellington Street 395, rue Wellington Ottawa ON K1A0N4 Ottawa ON K1A 0N4 Canada Canada Your file Votre reference ISBN: 978-0-494-91864-7 Our file Notre reference ISBN: 978-0-494-91864-7 NOTICE: AVIS: The author has granted a non­ L'auteur a accorde une licence non exclusive exclusive license allowing Library and permettant a la Bibliotheque et Archives Archives Canada to reproduce, Canada de reproduire, publier, archiver, publish, archive, preserve, conserve, sauvegarder, conserver, transmettre au public communicate to the public by par telecommunication ou par I'lnternet, preter, telecommunication or on the Internet, distribuer et vendre des theses partout dans le loan, distrbute and sell theses monde, a des fins commerciales ou autres, sur worldwide, for commercial or non­ support microforme, papier, electronique et/ou commercial purposes, in microform, autres formats. paper, electronic and/or any other formats. The author retains copyright L'auteur conserve la propriete du droit d'auteur ownership and moral rights in this et des droits moraux qui protege cette these. Ni thesis. Neither the thesis nor la these ni des extraits substantiels de celle-ci substantial extracts from it may be ne doivent etre imprimes ou autrement printed or otherwise reproduced reproduits sans son autorisation. without the author's permission. In compliance with the Canadian Conformement a la loi canadienne sur la Privacy Act some supporting forms protection de la vie privee, quelques may have been removed from this formulaires secondaires ont ete enleves de thesis. cette these. While these forms may be included Bien que ces formulaires aient inclus dans in the document page count, their la pagination, il n'y aura aucun contenu removal does not represent any loss manquant. of content from the thesis. Canada ABSTRACT Unlike extant birds and mammals, most non-avian theropods had large muscular tails. Digital muscle reconstructions based on measurements of fossil specimens and dissections of modem reptiles show that theM. caudofemoralis of many non-avian theropods was exceptionally large. Because M.the caudofemoralis is the primary hindlimb retractor, largeM. caudofemoralis masses give new evidence in favor of greater athleticism. The tails of theropods had a dynamic evolution and became specialized for a wide range of additional functions in various lineages. In Ceratosaurus the tail may have been adapted for swimming. In the South American abelisaurs, the angle of the caudal ribs was gradually adjusted to facilitate an even largerM. caudofemoralis that probably increased maximum running performance. In oviraptorosaurs, the tail supported a fan of feathers, and appears to have become modified for courtship displays. In dromaeosaurs, caudal rods may have allowed the tail to serve as an aerial rudder. ACKNOWLEDGEMENTS This research was made possible by the support of the Dinosaur Research Institute, the Korean-Mongolian International Dinosaur Project and the University of Alberta China Institute. I wish to thank John Acorn (University of Alberta), Victoria Arbour (University of Alberta), Robert Bakker (Houston Museum of Natural Science), Philip Currie(University of Alberta), Robert Holmes (University of Alberta), Pierre Lemelin (University of Alberta), Heinrich Mallison (Museum fiir Naturkunde), Alison Murray, and Eric Snively (Ohio University) for their repeated council and for many fruitful discussions about dinosaur tails. I also wish to extend my gratitude to Rinchen Barsbold (Paleontological Center of the Mongolian Academy of Sciences), Michael Brett-Surman (Smithsonian Institution National Museum of Natural History), Paige Johnson (Natural History Museum of Los Angeles County), Carl Mehling (American Museum of Natural History), Mark Norell (American Museum of Natural History), Brandon Strilisky (Royal Tyrrell Museum of Palaeontology), and Chinsorig Tsogtbaatar (Paleontological Center of the Mongolian Academy of Sciences) for their indispensable assistance in navigating the enormous storerooms of their respective institutions. Scott Hartman and Lida Xing merit my gratitude (and envy) for their stunning artistic skills and talents, which were graciously lent to this project. Special thanks are also owed to Joe Barter (Duke University) for his hospitality and assistance in recording tail measurements and to Eva Koppelhus (University of Alberta) and Alejandro Kramarz (Museo Argentino de Ciencias Naturales “B. Rivadavia”) for their help in photographing specimens. Lastly, I thank Michael Caldwell for his unhesitating willingness to sacrifice many tails from his sizable frozen reptile collection. TABLE OF CONTENTS Abstract Acknowledgements List of Tables List of Figures Institutional Abbreviations Introduction............................................................................................................1 Chapter 1 The Tail ofTyrannosaurus : Reassessing the Size and Locomotive Importance of theM. caudofemoralis in Non-avian Theropods............................................................................................ 5 1.1 Introduction......................................................................................... 5 1.2 Anatomy................................................................................................8 1.3 Computer Modeling...........................................................................11 1.4 Biomechanics......................................................................................12 1.5 Caudal Musculature and Osteological Correlates of Extant Reptiles................................................................................................16 1.6 Evidence for the Posterior Taper Point and Ventral Boundary of the M. caudofemoralis in Non-avian Theropods............................ 24 1.7 Evidence for the Lateral Boundary ofM. the caudofemoralis in Non-avian Theropods....................................................................... 30 1.8 Muscle Reconstruction.................................................................... .32 1.9 Biomechanics..................................................................................... 39 1.10 Discussion........................................................................................ 39 1.11 Bibliography.................................................................................... 47 Chapter 2 Dinosaur Speed Demon: Caudal MusculatureCarnotaurus of and Implications for the Evolution of South American Abelisaurids.................................................................................... 54 2.1 Introduction...................................................................................... 54 2.2 Reconstruction Method and Assumptions...................................... 59 2.3 Reconstruction Results..................................................................... 69 2.4 Functional Implications.................................................................... 74 2.5 Evolutionary Context........................................................................ 77 2.6 Conclusion......................................................................................... 81 2.7 Bibliography...................................................................................... 84 Chapter 3 Oviraptorosaur Tail Forms and Functions.................................... 88 3.1 Introduction....................................................................................... 88 3.2 Caudal Osteology.............................................................................. 89 3.3 Caudal Musculature......................................................................... 93 3.4 Discussion.......................................................................................... 98 3.5 Bibliography.................................................................................... 105 Chapter 4 Dragon Tails: Convergent Caudal Morphology in Winged Archosaurs........................................................................................I l l 4.1 Introduction......................................................................................I l l 4.2 Materials and Methods....................................................................115 4.3 Results...............................................................................................120 4.4
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