A Glyptosaurine Lizard from the Eocene
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East Tennessee State University Digital Commons @ East Tennessee State University Electronic Theses and Dissertations Student Works 8-2013 A Glyptosaurine Lizard from the Eocene (late Uintan) of San Diego, California, and Implications for Glyptosaurine Evolution and Biogeography David Moscato East Tennessee State University Follow this and additional works at: https://dc.etsu.edu/etd Part of the Biodiversity Commons, Evolution Commons, and the Paleontology Commons Recommended Citation Moscato, David, "A Glyptosaurine Lizard from the Eocene (late Uintan) of San Diego, California, and Implications for Glyptosaurine Evolution and Biogeography" (2013). Electronic Theses and Dissertations. Paper 1176. https://dc.etsu.edu/etd/1176 This Thesis - Open Access is brought to you for free and open access by the Student Works at Digital Commons @ East Tennessee State University. It has been accepted for inclusion in Electronic Theses and Dissertations by an authorized administrator of Digital Commons @ East Tennessee State University. For more information, please contact [email protected]. A Glyptosaurine Lizard from the Eocene (late Uintan) of San Diego, California, and Implications for Glyptosaurine Evolution and Biogeography _________________________ A thesis presented to the faculty of the Department of Geosciences East Tennessee State University In partial fulfillment of the requirements for the degree Master of Science in Geosciences _________________________ by David A. Moscato August 2013 _________________________ Jim I. Mead, Chair Blaine W. Schubert Steven C. Wallace Keywords: Glyptosaurinae, Glyptosaurus sylvestris, San Diego County, Santiago Formation Uintan, biogeography ABSTRACT A Glyptosaurine Lizard from the Eocene (late Uintan) of San Diego, California, and Implications for Glyptosaurine Evolution and Biogeography by David Moscato Glyptosaurine lizards (family Anguidae) are known exclusively from the Paleogene of North America and Eurasia. In North America these lizards are largely restricted to the intermontane basins along the Rocky Mountains, with only sparse, indeterminately-identified skeletal elements known from outside of this region. In this study I describe a new specimen assignable to G. sylvestris, notable for being recovered from the late Uintan of the Santiago Formation in southern California, significantly outside the known geographic range of well-preserved glyptosaurine fossils. The presence of Glyptosaurus in southern California at a time of widespread geographic change and regional endemism in mammalian faunas, when also considering the results other studies of Eocene lizards, indicates a pattern of evolution for lizards different from the turnovers and regional restrictions observed in mammals. The specimen described here shows features consistent with ontogenetic variation and may help to provide insight into the life history of glyptosaurine lizards. 2 ACKOWLEDGMENTS I’m very grateful to Robert Sullivan for introducing me to SDNHM 75932, and to the fascinating family of glyptosaurine lizards, for access to his cast of my main comparative specimen, UCMP 126000, and for helpful advice and critiques during this study. I thank Tom Deméré and Kesler Randall for granting me access to this and other glyptosaurine specimens, and I thank both men, along with Brad Riney, for access to information about the original excavations that recovered this specimen. I thank the staff at the Gray Fossil Site in Tennessee for access to preparatory equipment during fossil preparation of SDNHM 75932, and especially Shawn Haugrud for offering expert advice and assistance during fossil preparation. I thank Sandy Swift for help with photography and figure-making. I thank Carl Mehling for access to the glyptosaurine specimens at the AMNH. I am thankful to Blaine Schubert and Steven Wallace for serving on my thesis committee and offering support and advice. I thank the Don Sunquist Center for Excellence in Paleontology and the ETSU Departments of Geosciences and Biology for financial support during this study. I thank Steven Jasinski for offering plenty of advice, criticism, and frequent and sometimes welcome distractions. I thank Eric Lynch, Leigha King, and all of my other fellow graduate students and colleagues who offered advice, guidance, and company throughout the course of this project and my graduate school years. I am immensely grateful to Jim Mead, for serving as my thesis committee chair, for offering mounds of advice, and for 3 years of guidance, patience, and encouragement. 3 TABLE OF CONTENTS Page ABSTRACT ..................................................................................................................................2 ACKNOWLEDGMENTS ..............................................................................................................3 LIST OF TABLES ...........................................................................................................................6 LIST OF FIGURES ........................................................................................................................7 Chapter 1. INTRODUCTION ......................................................................................................................8 Taxonomic History ..............................................................................................................9 Distribution ........................................................................................................................14 Local Geology ....................................................................................................................16 2. MATERIALS AND METHODS ..............................................................................................18 3. FOSSIL DESCRIPTION AND IDENTIFICATION OF SDNHM 75932 ................................25 Systematic Paleontology ....................................................................................................25 Type Species ..........................................................................................................25 Revised Diagnosis ..................................................................................................25 Material ..................................................................................................................25 Locality and Horizon .............................................................................................26 Diagnosis................................................................................................................26 Morphological Description ................................................................................................26 Osteoderms ............................................................................................................26 Maxillae .................................................................................................................27 Jugals......................................................................................................................29 4 Prefrontal................................................................................................................29 Lacrimal .................................................................................................................30 Frontals ..................................................................................................................30 Additional Cranial Elements ..................................................................................31 Mandibles ...............................................................................................................31 Vertebrae ................................................................................................................32 Left humerus ..........................................................................................................32 Additional Post-cranial Elements ..........................................................................32 Comparative Description .......................................................................................34 Remarks .................................................................................................................36 References ..........................................................................................................................36 4. DISCUSSION ...........................................................................................................................38 Comparison with UCMP 126000.......................................................................................39 The Eocene of North America ...........................................................................................42 Eocene Biogeography of Glyptosaurinae ..........................................................................44 Future Study .......................................................................................................................48 5. CONCLUSIONS .......................................................................................................................49 REFERENCES .............................................................................................................................51 APPENDIX: List of Comparative Specimens ..............................................................................58 VITA ............................................................................................................................................61