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Puijila Darwini Evidence for independent acquisition of aquatic specializations in pinnipeds (seals, sea lions, and walruses): insights from study of the phylogenetic position, locomotor behaviour and description of the stem pinniped, Puijila darwini by Ryan Paterson A thesis submitted to the Faculty of Graduate and Postdoctoral Affairs in partial fulfillment of the requirements for the degree of Master of Science in Earth Sciences Carleton University Ottawa, Ontario © 2017, Ryan Paterson Abstract Monophyly of pinnipeds (seals, sea lions, and walruses) is well-established. However, it is difficult to reconcile a monophyletic origin of pinnipeds with the disparate locomotory modes and associated skeletal morphologies observed between the extant families. In this study, the skeletal anatomy of Puijila darwini, a key putative stem pinniped from Canada’s High Arctic, is fully described. A biomechanical analysis, using functional limb indices of extant carnivorans to predict locomotory modes in extinct taxa, confirms the aquatic adaptations of Puijila, and identifies it as a forelimb-dominated swimmer. Phylogenetic analyses of molecular and morphological data in isolation recover Puijila as a stem pinniped, and provide strong support for pinniped monophyly. However, a phylogenetic analysis combining molecular and morphological data together recovers an unconventional topology, suggesting the molecular and morphological data are incongruent. Closer scrutiny of previously-proposed pinniped synapomorphies suggests many features shared between seals, sea lions, and walruses arose in parallel. ii Acknowledgements I am grateful to the staff of the Canadian Museum of Nature for assisting with access to figures and specimens and the Government of Nunavut for allowing us to study NUFV-405. Special thanks go to Joanna Northover, Alex Tirabasso, Roger Bull, Jordan Mallon, Danielle Fraser, Kieran Shepherd, and Margaret Currie. Likewise, I would like to thank the staff and students at Carleton. Special thanks go to Tim Mount and Michael Ryan for their wisdom and advice. I also thank Fred Gaidies, for assistance with CT scans. Without the guidance and company of my fellow lab members, Arjan Mann, Jade Atkins, and Michael Thompson, my thesis, but more importantly, my sanity during my time at Carleton, would be much worse for wear. I would also like to thank SD, YM, and SM for advice on navigating graduate school. I must also thank MF for her endless support. For assistance and access to fossil collections, I thank: W. Simpson (FMNH), J Galkin (AMNH), C. Sidor, R. Eng, M. Riven, J. Bradley (Burke), F. Mayer (BNHM), D. Bohaska (NMNH), N. Famoso, G Retallack, G. Davis (UOMNH), J. Samuels (JODA), A. Pritchard, J. Gauthier (YPM), K. Seymour, D.C. Evans, B. Lim, J. Miller (ROM), C. de Muizon, G. Billet (MNHN), R. Marchant (MGL), G. Roessner (BSP), and E. Robert (FSL). I am thankful for funding provided by a Burke-VPCSG, a Paleontological Society student research grant, and an NSERC CGS-M to Ryan Paterson, and a NSERC discovery grant to Hillary Maddin. For useful discussion on phylogenetics and taxonomy, and their encouragement to tackle this research question, I thank Susumu Tomiya, John Flynn, Annalisa Berta, iii Thomas Deméré, Thomas Cullen, Xiaoming Wang, and Christian Kammerer. I am indebted to Naoki Kohno, who shared with me a draft of phylogenetic characters and codings to build on, and helped formulate my research question. I must also thank Joanna Northover, for her previous work on the skeleton of Puijila darwini. Special thanks go to my supervisors – Hillary Maddin and Natalia Rybczynski. I am grateful for the opportunity to work with two of the most respected and influential women in my field, and I thank them both for their ceaseless encouragement and patience. Finally, I would not have veered down this path without the encouragement of my mother, who also first introduced me to the work of Natalia by cutting out a newspaper clipping reporting on the very specimen that I would later write this thesis on. iv Table of Contents Abstract .............................................................................................................................. ii Acknowledgements .......................................................................................................... iii Table of Contents .............................................................................................................. v List of Tables .................................................................................................................... vi List of Figures .................................................................................................................. vii List of Appendices ............................................................................................................. x 1 Chapter 1: Introduction ............................................................................................. 1 2 Chapter 2: Complete description of Puijila darwini and inferences on the plesiomorphic swimming condition of pinnipeds ........................................................... 4 1.1 Abstract .......................................................................................................................... 4 1.2 Introduction .................................................................................................................... 5 1.3 Materials and Methods ................................................................................................. 11 Specimens Examined ............................................................................................... 11 Imaging .................................................................................................................... 12 Data Analysis ........................................................................................................... 14 1.4 Systematic Paleontology .............................................................................................. 15 1.5 Comparative Description .............................................................................................. 19 1.6 Discussion of Skeletal Morphology .............................................................................. 93 The Auditory Region ............................................................................................... 94 The Dentition ......................................................................................................... 101 1.7 Biomechanical Analysis ............................................................................................. 101 Results .................................................................................................................... 101 Discussion .............................................................................................................. 105 1.9 Conclusion .................................................................................................................. 110 v 3 Chapter 3: Total evidence phylogenetic analysis of pinnipeds indicates mulitple returns to the sea ........................................................................................................... 112 1.1 Abstract ...................................................................................................................... 112 1.2 Introduction ................................................................................................................ 113 1.3 Materials and Methods ............................................................................................... 120 Selection of Taxa ................................................................................................... 121 Analysis of Molecular Data ................................................................................... 131 Analysis of Morphological Data ............................................................................ 133 Total Evidence Analysis ........................................................................................ 136 1.4 Results ........................................................................................................................ 135 Molecular Only ...................................................................................................... 138 Total Morphology .................................................................................................. 138 Craniomandibular Only.......................................................................................... 141 Craniomandibular + Dental Only ........................................................................... 141 Postcranial Only ..................................................................................................... 142 Parsimony .............................................................................................................. 142 Total Evidence Analysis ........................................................................................ 144 1.5 Discussion................................................................................................................... 147 1.6 Conclusion .................................................................................................................. 174 4 Chapter 4: Conclusion ............................................................................................ 176 Appendices ....................................................................................................................
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