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UC Santa Barbara UC Santa Barbara Electronic Theses and Dissertations Title Miocene ungulates from Laguna del Laja, Chile, and an assessment of the Laguna del Laja faunas Permalink https://escholarship.org/uc/item/88j4t8kw Author Luna, Daniel Alexander Publication Date 2015 Peer reviewed|Thesis/dissertation eScholarship.org Powered by the California Digital Library University of California UNIVERSITY OF CALIFORNIA Santa Barbara Miocene ungulates from Laguna del Laja, Chile, and an assessment of the Laguna del Laja faunas. A dissertation submitted in partial satisfaction of the requirements for the degree Doctor of Philosophy in Earth Science by Daniel Alexander Luna Committee in charge: Professor André Wyss, Chair Professor Susannah Porter Professor Bruce Tiffney June 2015 The dissertation of Daniel Alexander Luna is approved. ____________________________________________ Susannah Porter ____________________________________________ Bruce Tiffney ____________________________________________ André Wyss, Committee Chair Miocene ungulates from Laguna del Laja, Chile, and an assessment of the Laguna del Laja faunas. Copyright © 2015 by Daniel Alexander Luna iii ACKNOWLEDGEMENTS This dissertation represents a culmination of many things I’ve learned, and though much of that knowledge is related to South American paleontology, there have also been other important lessons along the way. In my experience, the most valuable lessons often involve exceptional teachers. Indeed, I have received substantial support and guidance throughout this undertaking. I owe a debt of gratitude to many individuals and institutions, but the greatest share of my thanks goes to my advisor, Andy Wyss. Not only has Andy been an excellent mentor, introducing me to several different phases of paleontological discovery, but he has also become a friend and role model. His patience, kindness, and encouragement have been constant, and these virtues serve as inspiring examples to follow in my own life. I think I’d need a sixth chapter in this dissertation to adequately convey the full range of my respect and appreciation for Andy, but I know that he would humbly deflect such praise, and that he values concision. Over the years, I’ve learned that, like any vocation, research can be enriched immeasurably by the people you’re working with. I’ve been extremely fortunate to be part of such an excellent team, including Andy, John Flynn, and Darin Croft. I’m truly humbled by what they’ve been able to accomplish together, and their support has given this phase of my life significance far beyond the academic. Visiting several natural history museums, I have a plethora of directors, curators, and staff to thank. The number of people on this list prevents me from individually recognizing them all, but without their help much of this work would have been impossible. In particular, I’d like to acknowledge Marcelo Reguero at the Museo de La Plata and Alejandro Kramarz at the Museo Argentino de Ciencas Naturales. Marcelo and Alejandro not only offered me iv extended access to the fossil collections they curate, but they also helped me feel professionally and personally welcome, making my time in Argentina all the more rewarding. Also, Ana Balcarcel at the American Museum of Natural History deserves much credit for preparing many of the fossils described in this study, and graciously facilitating all my work at the AMNH; I’m glad to count her as a close friend. Funding for this museum research was generously provided by the Fulbright Program and the Geological Society of America. The UCSB Earth Science professors, graduate students, and staff have made my time here enjoyable, enriching, and productive. Being part of this department is one of the best decisions I’ve ever made, and I’m glad to have learned a thing or two about rocks along the way. I’m especially fortunate to have Susannah Porter and Bruce Tiffney on my committee. In addition to being wonderful people, thoughtful scientists, and careful editors, they are also inspired and inspiring educators. I’ve learned much from Susannah and Bruce, and as the next phase of my career begins, I hope to pass on their knowledge and passion to my own students. Finally I’d like to thank my family. To my parents, Richard and Fanny, and my sisters, Tania and Jessica: your love and support mean so much to me. Without a doubt, the most rewarding aspect of this accomplishment is that we share it together. v VITA OF DANIEL ALEXANDER LUNA March 2015 Education Duke University 2002-2006 Majors: BS in Biology: concentration in evolutionary biology BA in Religion: concentration in Christian history and thought University of California, Santa Barbara 2008-present PhD student in the Earth Science Department Research: mammalian paleontology Professional Employment Biology Guest Lecturer at East Carteret High School, NC 2004 Teaching Assistant at Duke University 2006 Teaching Assistant at UCSB 2008-2014 Teaching Associate at UCSB 2012-present Summer Mentorship Program at UCSB 2012 School for Scientific Thought at UCSB 2012 Summer Teaching Institute for Associates, UCSB 2013, 2014 Publications Luna, D.A., J.J. Flynn, D.A. Croft, and A.R. Wyss. 2011. Endemic South American Ungulate (Mammalia) Fossils from the Laguna del Laja Region, Andean Main Range, Central Chile. Ameghiniana 48 (suppl. 4) R126. Luna, D., Flynn, J., Croft, D., Wyss, A. 2013. Taxonomy, Biogeography, and Phylogeny of Miocene Endemic South American Ungulates (Mammalia) from the Laguna del Laja Region, Andean Main Range, Central Chile. Journal of Vertebrate Paleontology, Program and Abstracts, 2013, 166. Honors and Awards Graduated magna cum laude from Duke University 2006 Duke University Department of Biology: James B. Rast Award for Comparative Organismal Biology 2006 UCSB: Eugene Cota-Robles Central Fellowship 2008-2012 Recipient of GSA Graduate Research Grant 2010 Fulbright Fellow: Argentina 2011 Wendell Phillips Woodring Memorial Graduate Fellowship 2011 R. V. Fisher Scholarship in Volcanology 2012 vi ABSTRACT Miocene ungulates from Laguna del Laja, Chile, and an assessment of the Laguna del Laja faunas. by Daniel Alexander Luna The unique history of mammals in South America has long provided significant evolutionary and geological insights, but the continent’s fossil record is strongly biased toward the lowlands of Argentine Patagonia. Recent collecting efforts in the Andean Main Range of Chile, near Laguna del Laja (LdL) (~37.5º S, 71º W), have yielded a stratigraphically superposed series of early to late Miocene fossil mammal assemblages, shedding light on the poorly known extra-Patagonian history of South American Neogene mammals. Several hundred specimens have been recovered from the Cura-Mallín and overlying Trapa-Trapa formations at LdL. Nearly all of these fossils were collected from a well-described stratigraphic sequence that includes 17 high precision 40Ar/39Ar ages. This robust temporal framework encompasses fossiliferous horizons spanning ~20-9 Ma. Herein I provide a detailed account of the ungulates from the Cura-Mallín Formation at LdL; these range in age from ~20-15 Ma (early to middle Miocene). Dentitions referred to Protypotherium praerutilum, a well-known but inadequately diagnosed species, motivated a long overdue (but preliminary) taxonomic revision. Occurrences of Protypotherium, Colpodon, and Astrapothericulus, together with radioisotopic ages, indicate that faunas vii spanning the Colhuehuapian and Santacrucian South American Land Mammal “Ages” (SALMAs) occur in direct stratigraphic superposition at LdL. These deposits have also yielded five new genera of typotherians (Notoungulata); this high level of endemism has also been noted among rodent faunas from LdL. The five new taxa described in this study are included in rigorous phylogenetic analyses of Interatheriinae and Hegetotheriidae (Typotheria, Notoungulata), providing new hypotheses of morphological evolution within these clades, and documenting independent yet apparently simultaneous radiations of interatheres and hegetotheres with ever-growing (hypselodont) dentitions. A significant majority of fossils from LdL are small-bodied taxa (e.g., rodents and typotherian notoungualtes) represented by dental and cranial elements. This size distribution is unusual compared to other well-known early Miocene faunas, and may reflect differential transport of skeletal elements in lahar-associated depositional settings. The high level of endemism across multiple SALMAs at LdL is also striking, particularly considering the geographic proximity of faunas from LdL with roughly coeval counterparts in neighboring regions of Argentina. This provinciality of the Andean faunas, relative to Argentine assemblages, likely reflects sampling of a regionally distinct and isolated paleoenvironment. viii TABLE OF CONTENTS Chapter 1. Introduction..…………………………………………………...………...1 Chapter 2. Early Miocene interatheriines (Interatheriidae, Typotheria, Notounuglata) from the Laguna del Laja region, with a preliminary revision of Protypotherium and a phylogeny of Interatheriinae……………………………..47 Chapter 3. New hegetotheriids (Typotheria, Notoungulata) from the Laguna del Laja region, and a phylogeny of Hegetotheriidae……………………………...144 Chapter 4. A consideration of taphonomic biases impacting the fossil mammal assemblages from the Laguna del Laja region…………………………………….200 Chapter 5. Summary and Synthesis of Laguna del Laja Faunas…………………..238 ix Chapter 1. Introduction Overview of Cenozoic mammals in South America………………………………….3 South American