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Proquest Dissertations University of Alberta Evolution, biomechanics, and function of the tail club of ankylosaurid dinosaurs (Ornithischia: Thyreophora) by Victoria Megan Arbour © 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 Edmonton, Alberta Spring 2009 Library and Archives Bibliotheque et 1*1 Canada Archives Canada Published Heritage Direction du Branch Patrimoine de Pedition 395 Wellington Street 395, rue Wellington OttawaONK1A0N4 Ottawa ON K1A 0N4 Canada Canada Your We Votne r&temnce ISBN: 978-0-494-54648-2 Our file Notre r6f6rence ISBN: 978-0-494-54648-2 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 reproduce, 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, distribute 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 §tre 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. 1+1 Canada This thesis is dedicated to all of my mentors, past and present, who have helped me get to where I am today. Abstract Modified distal caudal vertebrae (the handle) and large terminal osteoderms (the knob) form the tail club of ankylosaurid dinosaurs. It has been assumed that the club was used as a weapon, but the biological feasibility of this behaviour has not been tested. Computed tomographic scans of tail clubs referred to Euoplocephalus, and measurements of free caudal vertebrae, were used to estimate the impact force of clubs of various sizes. Tails are modeled as segments for which mass, muscle cross-sectional area, torque, and angular acceleration are calculated. Large knobs could generate sufficient force to break bone during impacts, but average and small knobs could not. Finite element analyses showed that stress is distributed evenly along the handle, preventing fracture of the club during impacts. Tail clubbing behaviour is feasible in ankylosaurids, but it remains unknown whether the tail was used for interspecific defense, intraspecific combat, or both. Acknowledgements I extend many thanks to my supervisor, Philip Currie, for the opportunity to conduct this research and for his guidance throughout the course of this project. I am also grateful to Eva Koppelhus and my committee members Alison Murray and Michael Caldwell for their advice and assistance. The students of the Laboratory for Vertebrate Paleontology have provided endless academic support and friendship and I thank them all. Thanks to the many people who provided access and assistance at their institutions: C. Mehling (AMNH), K. Shepherd and M. Feuerstack (CMN), L. Ivy and K. Carpenter (DMNH), B. Demchig (MPC), D. Evans and B. Iwama (ROM), J. Gardner and B. Strilisky (TMP), and S. Harpham and P. Correia (Univ. of Alberta Anthropology). I thank B. Demchig, P. Currie, E. Koppelhus, M. Ryan and the staff of Nomadic Expeditions for providing me with the opportunity to visit collections and conduct fieldwork in Mongolia. G. Pinto and P. Bell helped prepare UALVP 47273 and I thank M. James for assistance with preparation of UALVP 31. The University of Oslo graciously provided a cast of ZPAL MgD-l/113. P. Currie, E. Snively, and M. Burns provided specimen photographs. Many thanks to R. Lambert for allowing access to the ABACUS CT scanning facility at the University of Alberta Hospital, and to G. Schaffler and the ABACUS technicians for help during CT scanning of TMP 1983.36.120, UALVP 47273, and UALVP 16247. ROM 788 was scanned at CML Healthcare in Mississauga, Ontario, and I thank T. Ladd for his assistance organizing the scan. Many, many thanks to D. Evans and B. Iwama for preparing ROM 788 for CT scanning in the midst of a new gallery opening! M. James, M. Burns, and E. Snively assisted with transporting specimens for CT scanning. J. Li and M. Lawrenchuck (Materialise) provided technical assistance with Mimics, and Anne Delvaux (Beaufort Analysis, Inc.) provided technical assistance with Strand7. H. Mallison (Museum fur Naturkunde, Berlin) provided advice on digital imaging of fossils. I have been fortunate to have had funding from both the Natural Sciences and Engineering Research Council and Alberta Ingenuity. The University of Alberta Graduate Students Association, the Department of Biological Sciences, and the Dinosaur Research Institute have also provided funds for travel and CT scanning, and their assistance is gratefully acknowledged. Finally, I cannot ever express enough thanks to my parents, Edith and Joseph Arbour, to my sister Jessica Arbour, and to Peter Maguire, for their kindness, support, and faith in me. Thank you all. Table of Contents Abstract Acknowledgements List of Tables List of Figures Institutional Abbreviations Chapter 1: Introduction and background 1 1.1 Introduction 1 1.2 Phylogeny of the Ankylosauria 3 Chapter 2: Morphology of ankylosaurid pelves and tails and the evolution of ankylosaurid tail clubs 7 2.1 Introduction 7 2.2 Materials and methods 8 2.3 Pelvic morphology of Euoplocephalus 9 2.4 Caudal morphology 13 2.4.1 Nodosaurids 13 2.4.2 Basal ankylosaurids 14 2.4.3 Derived ankylosaurids 17 2.5 Discussion 35 2.5.1 Number of species represented by material referred to Euoplocephalus 35 2.5.2 Causes of tail club variation 43 2.5.3 Evolution of the ankylosaurid tail club 44 2.6 Conclusions 48 Chapter 3: Ankylosaurid tail and pelvis pathologies 50 3.1 Introduction 50 3.2 Description 51 3.2.1 AMNH 5409, pelvis and sacrum.... 51 3.2.2 AMNH 5337, pelvis and sacrum 52 3.2.3 AMNH 5245, two anterior free caudals 53 3.2.4 TMP2005.09.75, sacrocaudal 55 3.2.5 TMP 1985.36.70, proximal free caudal vertebra 55 3.2.6 AMNH 2062, anterior free caudal vertebra 56 3.2.7 ROM 1930, anterior free caudal vertebra and last free caudal vertebra 56 3.2.8 TMP 1992.36.344, posterior free caudal vertebra 58 3.2.9 AMNH 5404, two free caudal vertebrae 58 3.2.10 ROM 1930, haemal arch 60 3.2.11 TMP 1983.36.120, tail club 60 3.2.12 ROM 788, tail club 62 3.3 DISCUSSION 63 3.3.1 Diagnoses 64 3.3.1.1 AMNH 5245, AMNH 2062, ROM 1930 haemal arch and spine, TMP 1985.36.70, and TMP 2005.09.75: osteomyelitis and periostitis 65 3.3.1.2 ROM 1930, proximal free caudal vertebra and last free caudal vertebra 70 3.3.1.3 AMNH 5404, AMNH 5337, and AMNH 5409: metastatic cancer...70 3.3.1.4 ROM 788, TMP 1983.36.120, and the challenges of identifying pathologies in osteoderms ...73 3.3.2 Frequency and patterns of pathologies in ankylosaurid taxa 76 3.3.3 Behavioural implications 79 3.4 Conclusions 82 Chapter 4: Ankylosaurid caudal musculature 84 4.1 Introduction 84 4.2 Review of epaxial and intrinsic trunk and tail muscles of extant reptiles 85 4.3 Ossified tendons of ornithischian dinosaurs 88 4.4 Inferred tail musculature of ankylosaurids 89 Chapter 5: Analysis of tail swinging ability in ankylosaurid dinosaurs 97 5.1 Introduction 97 5.2 Materials and methods 97 5.3 Description of club internal morphology from CT scans 98 5.4 Analysis of tail club motion and impact force 104 5.4.1 Analysis of a small knob and tail, ROM 784/UALVP 47273 108 5.4.1.1 Determining the volume of the tail bones and muscles 110 5.4.1.2 Determining knob volume 117 5.4.1.3 Angle of articulation between free caudal vertebrae 119 5.4.1.4 Calculating T, I, and co 122 5.4.1.5 Sensitivity analyses 129 5.4.2 Analysis of a large tail and knob, ROM 788/AMNH 5245 136 5.4.2.1 Estimates of bone and muscle mass and volume 136 5.4.2.2 Calculating T, I, and co 141 5.4.3 Analysis of a mid-sized tail and knob, UALVP 16247 141 5.4.3.1 Estimates of bone and muscle mass and volume 142 5.4.3.2 Calculating T, I, and w 143 5.5 Discussion 144 5.6 Conclusions 146 Chapter 6: Finite element analyses of ankylosaurid tail clubs 148 6.1 Introduction 148 6.2 Materials and Methods 149 6.2.1 Analysis 1 154 6.2.2 Analysis 2 154 6.2.3 Analysis 3 155 6.2.4 Analysis 4 155 6.2.5 Analysis 5 157 6.2.6 Analysis 6 158 6.3 Results 159 6.3.1 Analysis 1: Effect of knob size and impact force 159 6.3.2 Analysis 2: Impact site analysis 165 6.3.3 Analysis 3: Stress distributions in the handle vertebrae 165 6.3.4 Analysis 4: Postural role of the haemal arches 168 6.3.5 Analysis 5: Material properties 169 6.3.6 Analysis 6: Neural spine shape in different ankylosaurid taxa 169 6.4 Discussion 172 6.5 Conclusions 176 7.0 Conclusions 177 8.0 Literature Cited 182 Appendix 1 211 List of Tables Chapter 1: Table 1.1: Stratigraphic information for ankylosaurs discussed in this thesis.
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