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THE UPPERMOST LOWER EOCENE BLUE RIM FLORA FROM THE BRIDGER FORMATION OF SOUTHWESTERN WYOMING: FLORISTIC COMPOSITION, PALEOCLIMATE, AND PALEOECOLOGY By SARAH ELIZABETH ALLEN A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2017 © 2017 Sarah Elizabeth Allen To my parents ACKNOWLEDGMENTS Thank you to my advisor, Steven R. Manchester, for his guidance, support, and valuable comments. My committee members, Ellen Martin, Walter Judd, and Jonathan Bloch are gratefully acknowledged. Hongshan Wang spent hours curating Blue Rim fossils at the FLMNH and always provided a welcoming space to work in the collections. Paleobotany lab manager, Terry Lott, is acknowledged for his help with specimens and around the lab. Thank you also to the other members of the paleobotany lab: Greg Stull, Fabiany Herrera, Paula Mejia-Velasquez, Nareerat Boonchai, Jui Hui, Rebecca Koll, Fani Plascencia, Xiaoyan Liu, Yuling Na, Nathan Jud, Chris Nelson, Bob Spielbauer, Nazi Balmaki, Han Meng, and Li Long. Thank you to those who helped with fieldwork at Blue Rim in 2010, 2012. and 2014: Jim Barkley, Nareerat Boonchai, Sahale Casebolt, Ellen Currano, Don and Kathy Hopkins, Jui Hui, Grant Godden, Xiaoyan Liu, Terry Lott, Steve Manchester, Keith McCall, Paul Murphey, Mike Smith, and Greg Stull. I must add additional thanks to Steve for allowing me to use his van for fieldwork and to Sahale and Terry for help in driving between Wyoming and Florida in the summer of 2014. Scott Wing let me join him in the Bighorn Basin for some additional fieldwork experience in the summer of 2011. Additional fossil specimens studied were collected and donated to the FLMNH by Jane Landeen (who discovered the Blue Rim site), Jim Barkley, and Howard and Darlene Emry. Bruce Handley collected and donated material from Watson, UT to the UCMP at Berkeley. Work on this project was assisted by discussions with William Bartels, Nareerat Boonchai, Laura Calvillo-Canadell, Sergio Cevallos-Ferriz, Peter Crane, John Dransfield, Emmett Evanoff, Carol Furness, Gregg Gunnell, Madeline Harley, Christa Hofmann, David Jarzen, Nathan Jud, Chris Nelson, Kristen Porter-Utley, Bill Rember, Paula Rudall, Bandana 4 Samant, Selena Smith, Rashmi Srivastava, Elisabeth Wheeler, Scott Wing, and John-Paul Zonneveld. More extensive research collaborations with Steve Manchester, Greg Stull, Mac Alford, and Mike Smith are also appreciated. Many of the photos of macrofossils were taken by student workers and volunteers including: Catherine Snyder, Morgan Kerr, Ariel Guggino, Xiaojuan Zhou, and Megan Kean. Student research volunteers also documented and photographed macrofossils and many of the dispersed pollen slides. Thank you to William Paxton, Alyssa Zakala, Jonathan Wilson, and a special thanks and appreciation to Morgan Pinkerton for all of her hard work and research. Scott Wing, Kirk Johnson, and Diane Erwin provided access to fossil specimens studied at the USNM, the DMNS, and UCMP, respectively. M. E. Collinson provided comparative data on related fossils from the London Clay flora (Chapter 5). I also thank the herbarium staff at the FLMNH, Wageningen, Leiden, Kim Kersh at the University and Jepson Herbaria (UC Berkeley), and J. Solomon at the Missouri Botanical Garden for facilitating study of extant material. My participation in an NSF funded short course on Plant Anatomy (microMORPH) at the Arnold Arboretum of Harvard University in the summer of 2015 (instructors: Pieter Baas, Pam Diggle, William (Ned) Friedman, Peter Gasson, Elisabeth Wheeler) greatly facilitated my knowledge of wood anatomy and allowed me to complete that aspect of my dissertation project. Chris Nelson is acknowledged for preparing many of the recent wood slides. Thank you to all my teaching supervisors and support staff: Kent Vliet, Jack Putz, Ann Wagner, Stuart McDaniel, Norm Douglas, my fellow TA’s, and a special thanks to Christine Davis for her support and for helping me improve my teaching as part of the Plant Anatomy course. 5 Research funding was provided by an NSF Doctoral Dissertation Improvement Grant (DEB-1404895), the Evolving Earth Foundation, the Paleontological Society, and the UF Department of Biology Mildren Mason Griffith Grant. Additional travel support was provided by S.R. Manchester, the UF Dept. of Biology, UF Graduate Student Council. Thank you to the Department of Biology for guaranteeing teaching support and to the UF College of Liberal Arts and Sciences Dissertation Fellowship which enabled me to complete my dissertation in my final semester. Thank you also to UF Department of Biology and FLMNH financial staff members who helped to coordinate grant funds including: Shuronna Wilson, Ashley Gazich, Robb Stokes, Darlene Novak, and Leila Long. I also thank Karen Patterson, Tangelyn Mitchell, and Susan Spaulding from the UF Department of Biology and the library and interlibrary loan staff at UF. The FLMNH webmaster, Sarah Fazenbaker, provided assistance with setting up and facilitating my blog. And finally, thank you to my friends and family for their continued support. My UF friends, including Emily Woodruff and Elizabeth Hamman, were always a sounding board and a source of fun. Deep appreciation is given to Jared Desrochers who sweated out many years in Florida on my behalf and kept the fridge full when I did not have time to shop or cook. My parents took me on trips, let me fill up our suitcases with rocks, and encouraged my appreciation of the natural world. Their unwavering support was invaluable. 6 TABLE OF CONTENTS page ACKNOWLEDGMENTS ...............................................................................................................4 LIST OF TABLES .........................................................................................................................11 LIST OF FIGURES .......................................................................................................................13 LIST OF ABBREVIATIONS ........................................................................................................21 ABSTRACT ...................................................................................................................................22 CHAPTER 1 GEOLOGICAL, PALEONTOLOGICAL AND PALEOCLIMATIC CONTEXT ...............24 Part I: Regional Perspective ....................................................................................................24 Topographic and Geologic Setting ..................................................................................24 Geology and Sedimentological Origins of the Bridger Formation .................................31 Stratigraphic Members of the Bridger Formation ...........................................................33 The Bridgerian North American Land Mammal Age .....................................................34 Radiometric Dating .........................................................................................................36 Early Paleontological Work in the Bridger Formation ....................................................37 Fossil Fauna and Flora in the Bridger & Nearby Localities: 20th and 21st Centuries ......38 Regional Paleoenvironments and Paleoclimate Estimates ..............................................43 Part II: Local Geology and Depositional Environment at Blue Rim ......................................46 Location of the Blue Rim Escarpment ............................................................................46 General Geologic Observations .......................................................................................46 Geologic Field Observations about Specific Quarries ....................................................48 Vertebrate Fossils at Blue Rim ........................................................................................49 Invertebrate Fossils at Blue Rim .....................................................................................50 Depositional Environment ...............................................................................................50 Radiometric Ages ............................................................................................................52 Part III: Dissertation Overview ...............................................................................................55 Overarching Research Questions ....................................................................................55 Overview of the Following Chapters ..............................................................................55 2 LEAF FOSSILS FROM BLUE RIM .....................................................................................73 Part I: Leaves from the Isolated Channel Fill UF 19404 ........................................................75 Toothed Laminae .............................................................................................................75 Entire-margined Laminae ................................................................................................83 Summary of Isolated Channel Fill Leaves, Locality UF 19404 ......................................91 Part II: Dicotyledonous Leaf Morphotypes from the Lower Horizon ....................................92 Toothed Laminae .............................................................................................................92 Entire-margined Laminae ..............................................................................................114