New Specimens of Sparassodonta (Mammalia, Metatheria) From
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NEW SPECIMENS OF SPARASSODONTA (MAMMALIA, METATHERIA) FROM CHILE AND BOLIVIA by RUSSELL K. ENGELMAN Submitted in partial fulfillment of the requirements for the degree of Master of Science Department of Biology CASE WESTERN RESERVE UNIVERSITY January, 2019 CASE WESTERN RESERVE UNIVERSITY SCHOOL OF GRADUATE STUDIES We hereby approve the thesis/dissertation of Russell K. Engelman candidate for the degree of Master of Science*. Committee Chair Hillel J. Chiel Committee Member Darin A. Croft Committee Member Scott W. Simpson Committee Member Michael F. Benard Date of Defense July 20, 2018 *We also certify that written approval has been obtained for any proprietary material contained therein. ii TABLE OF CONTENTS NEW SPECIMENS OF SPARASSODONTA (MAMMALIA, METATHERIA) FROM CHILE AND BOLIVIA ....................................................................................................... i TABLE OF CONTENTS ................................................................................................... iii LIST OF TABLES ............................................................................................................. vi LIST OF FIGURES .......................................................................................................... vii ACKNOWLEDGEMENTS ................................................................................................ 1 LIST OF ABBREVIATIONS ............................................................................................. 4 ABSTRACT ........................................................................................................................ 7 1. INTRODUCTION ...................................................................................................... 8 2. AUSTRALOGALE LEPTOGNATHUS GEN. ET SP. NOV., A SECOND SPECIES OF SMALL SPARASSODONT (MAMMALIA, METATHERIA) FROM THE MIDDLE MIOCENE LOCALITY OF QUEBRADA HONDA, BOLIVIA .................... 13 2.1 INTRODUCTION .............................................................................................. 13 2.2 MATERIALS AND METHODS ....................................................................... 15 2.3 SYSTEMATIC PALEONTOLOGY .................................................................. 17 2.4 DESCRIPTION .................................................................................................. 19 2.5 DISCUSSION .................................................................................................... 30 2.5.1 The p3 locus in UATF-V-001900 ............................................................... 30 2.5.2 Systematic position of Australogale leptognathus ..................................... 34 2.5.3 Reduction of p3 in Metatherians ................................................................. 42 iii 2.5.4 Paleobiology of Australogale leptognathus ................................................ 44 2.5.5 The Sparassodont Fauna of Quebrada Honda and the Laventan SALMA . 47 3. A LATE EOCENE SPARASSODONT (MAMMALIA, METATHERIA, SPARASSODONTA) FROM THE LOCALITY OF LOS HELADOS (CENTRAL CHILE) ............................................................................................................................. 51 3.1 INTRODUCTION .............................................................................................. 51 3.2 MATERIALS AND METHODS ....................................................................... 53 3.3 SYSTEMATIC PALEONTOLOGY .................................................................. 53 3.4 DESCRIPTION .................................................................................................. 55 3.5 DISCUSSION .................................................................................................... 60 4. EOMAKHAIRA MOLOSSUS, A NEW BORHYAENOID SPARASSODONT (MAMMALIA, METATHERIA, SPARASSODONTA) FROM THE EARLY OLIGOCENE (?TINGUIRIRICAN) CACHAPOAL FAUNA, ANDEAN MAIN RANGE, CENTRAL CHILE ............................................................................................ 64 4.1 INTRODUCTION .............................................................................................. 64 4.2 MATERIALS AND METHODS ....................................................................... 68 4.3 SYSTEMATIC PALEONTOLOGY .................................................................. 70 4.4 DESCRIPTION .................................................................................................. 73 4.4.1 Cranium....................................................................................................... 77 4.4.2 Mandible ..................................................................................................... 86 4.4.3 Dentition ..................................................................................................... 92 iv 4.5 PHYLOGENETIC ANALYSIS ....................................................................... 118 4.6 DISCUSSION .................................................................................................. 127 4.6.1 Paleobiology of SGOPV 3490 .................................................................. 127 4.6.2 Carnassial Rotation in Sparassodonts ....................................................... 135 4.6.3 Proborhyaenidae and the Origin of Thylacosmilids ................................. 140 5. FUTURE DIRECTIONS ........................................................................................ 151 SUPPLEMENTARY INFORMATION ......................................................................... 155 LITERATURE CITED ................................................................................................... 278 v LIST OF TABLES Table 2.1. Mandibular depth of UATF-V-001900 compared to other small Neogene sparassodonts. ................................................................................................................... 20 Table 2.2. Measurements of the dentition and mandibular ramus of UATF-V-001900. .. 22 Table 2.3. Proportions of m1-2 in Australogale leptognathus gen. et. sp. nov. compared to other small sparassodonts and the slightly larger Sipalocyon gracilis. ........................ 23 Table 2.4. Comparison of features among Australogale leptognathus gen. et sp. nov. and other very small to medium-sized South American tritubercular metatherians. .............. 37 Table 3.1. Anteroposterior lengths (in mm) of the lower dentition of SGOPV 6200. ...... 59 Table 3.2. Lower molar row anteroposterior length (Lm1-4), estimated body mass, and relative dentary depth at m4 (m4D) of SGOPV 6200 and species of Pharsophorus and Plesiofelis. ......................................................................................................................... 61 Table 4.1. Measurements of the holotype of Eomakhaira molossus (SGOPV 3490) in mm. Greatest dorsoventral height of maxilla was measured from the alveolar border of P3 to the dorsal border of the maxilla. ................................................................................... 79 Table 4.2. Dental measurements of the holotype of Eomakhaira molossus (SGOPV 3490) in mm. ............................................................................................................................... 93 Table 4.3. Upper canine proportions of SGOPV 3490 compared to other sparassodonts, focusing on canine shape (ratio of anteroposterior length/labiolingual width) and relative canine size. ........................................................................................................................ 94 Table 4.4. Morphometric values of the dentition used to infer dietary habits in Eomakhaira molossus. .................................................................................................... 133 Table 4.5. Angle of inward canting of the posterior upper molars in sparassodonts. ..... 137 vi LIST OF FIGURES Figure 2.1. Temporal and geographical location of Quebrada Honda. ............................. 14 Figure 2.2. UATF-V-001900, Australogale leptognathus gen. et sp. nov. (holotype), right dentary fragment in A, labial; B, occlusal; and C, lingual views. .................................... 19 Figure 2.3. Photograph (A) and line drawing (B) of m1-2 of UATF-V-001900 in occlusal view. .................................................................................................................................. 25 Figure 2.4. Line drawings of m1-2 of (A) Australogale leptognathus, UATF-V-001900; (B) the small sparassodont Pseudonotictis pusillus, MLP 11-26, and (C) the didelphoid Hesperocynus dolgopolae, FMNH P14469 (modified from Abello et al., 2015), scaled to the same anteroposterior length, showing the greater resemblance of Australogale to small sparassodonts than didelphoids. .............................................................................. 28 Figure 2.5. X-ray (A) and micro-CT (B) images of UATF-V-001900, showing the lack of a replacement tooth below p3 (second tooth from right) and the fully formed anterior root of m3 (at left). ................................................................................................................... 31 Figure 2.6. Strict consensus tree of 8 most parsimonious trees showing the relationship of Australogale leptognathus among sparassodonts and other metatherians. ....................... 36 Figure 3.1. Map of Chile (left) and central Chile (inset box) showing the location of Los Helados (LH, at arrow) and other selected Paleogene Chilean fossil mammal localities of the