A Redescription and Phylogenetic Analysis of the Cretaceous Fossil Lizard Polyglyphanodon sternbergi Gilmore, 1940 by Meredith Austin Fontana B.S. in Biology, May 2011, The University of Texas at Austin A Thesis submitted to The Faculty of The Columbian College of Arts and Sciences of The George Washington University in partial fulfillment of the requirements for the degree of Master of Science August 31, 2014 Thesis directed by James M. Clark Ronald Weintraub Professor of Biology © Copyright 2014 by Meredith Austin Fontana All rights reserved ii This thesis is dedicated to the memory of my grandmother, Lee Landsman Zelikow – my single greatest inspiration, whose brilliant mind and unconditional love has profoundly shaped and continues to shape the person I am today. iii ACKNOWLEDGEMENTS I am deeply grateful to my graduate advisor Dr. James Clark for his support and guidance throughout the completion of this thesis. This work would not have been possible without his invaluable assistance and commitment to my success, and it has been a privilege to be his student. I would also like to express my appreciation to the additional members of my Master’s examination committee, Dr. Alexander Pyron and Dr. Hans-Dieter Sues, for generously contributing their knowledge and time toward this project and for providing useful comments on the manuscript of this thesis. I am especially grateful to Dr. Sues for allowing me access to the exquisite collection of Polyglyphanodon sternbergi specimens at the National Museum of Natural History. I am also extremely thankful to the many faculty members, colleagues and friends at the George Washington University who have shared their wisdom and given me persistent encouragement. Special thanks are due to Dr. Cathy Forster, Karen Poole, Joey Stiegler, Drew Moore, Dominic White, Dana Al-Meer and Rodrigo Figueiredo for always going out of their way to help me when needed, and for making the last few years so memorable. Finally, this thesis would not have been possible without the immense love and support of my family, for which I am truly blessed. I especially owe thanks to my greatest source of strength, my parents Robin and Brian, for their sacrifices, unflaggingly support of my dreams, and for always reminding me to believe in myself when faced with adversity. iv ABSTRACT A Redescription and Phylogenetic Analysis of the Cretaceous Fossil Lizard Polyglyphanodon sternbergi Gilmore, 1940 A detailed osteological description of Polyglyphanodon sternbergi (Polyglyphanodontia: Squamata), the most complete polyglyphanodontian lizard known from North America, is presented for the first time since Charles Gilmore first described this species in 1942. The material used for this description is currently housed at the Smithsonian National Museum of Natural History and consists of a large collection of well preserved, partially articulated skeletons and isolated elements representing nearly the entire skeleton. P. sternbergi’s taxonomy and systematics is reviewed, and its inclusion in a recent comprehensive morphological phylogenetic analysis is revised and reanalyzed. The results of this analysis support the placement of Polyglyphanodontia as a scleroglossan stem clade, and reveal six new unambiguous synapomorphies of Polyglyphanodontia and seven new autapomorphies for P. sternbergi. Unique morphological traits of P. sternbergi are discussed, including the convergence of certain features such as its dentition with modern teiids and the paleoecological significance of these features. v TABLE OF CONTENTS DEDICATION................................................................................................................. iii ACKNOWLEDGEMENTS ................................................................................................. iv ABSTRACT ...................................................................................................................... v LIST OF FIGURES ........................................................................................................... x LIST OF TABLES ........................................................................................................... xii INTRODUCTION ............................................................................................................... 1 Overview of the Systematics and Taxonomy of P. sternbergi .................................... 4 SYSTEMATIC PALEONTOLOGY ........................................................................................ 9 DESCRIPTION ................................................................................................................ 10 SKULL ........................................................................................................................ 10 Premaxilla ............................................................................................................... 10 Nasals ..................................................................................................................... 11 Frontals ................................................................................................................... 11 Postfrontal .............................................................................................................. 12 Postorbital ............................................................................................................... 13 Maxilla ................................................................................................................... 13 Jugal ....................................................................................................................... 14 Prefrontal ................................................................................................................ 15 Lacrimal ................................................................................................................. 16 Squamosal .............................................................................................................. 17 Quadrate ................................................................................................................. 17 vi Parietal.................................................................................................................... 18 Vomer ..................................................................................................................... 19 Palatine ................................................................................................................... 19 Pterygoid ................................................................................................................ 20 Ectopterygoid.......................................................................................................... 20 Braincase ................................................................................................................ 21 MANDIBULAR RAMUS ................................................................................................. 23 Dentary ................................................................................................................... 21 Splenial ................................................................................................................... 23 Angular ................................................................................................................... 24 Coronoid ................................................................................................................. 25 Prearticular ............................................................................................................. 25 Surangular .............................................................................................................. 25 Articular ................................................................................................................. 26 Dentition ................................................................................................................. 26 POSTCRANIAL SKELETON ............................................................................................ 28 Vertebrae ................................................................................................................ 28 Cervicals ................................................................................................................. 29 Dorsals.................................................................................................................... 31 Sacrals .................................................................................................................... 32 Caudals ................................................................................................................... 33 Ribs ........................................................................................................................ 34 Scapula ................................................................................................................... 35 vii Coracoid ................................................................................................................. 36 Clavicle .................................................................................................................. 36 Interclavicle ............................................................................................................ 37 Humerus ................................................................................................................