' 3 .44- E 4 - r-1-11-1 . ' ~ . Ill'll of the FLORIDA MUSEUM OF NATURAL HISTORY PLIOCENE MAMMALS FROM INCHASI, BOLIVIA: THE ENDEMIC FAUNA JUST BEFORE THE GREAT AMERICAN INTERCHANGE Federico Anaya and Bruce J. MacFadden Volume 39, No. 3, pp. 87-140 1995 U. ; ~.- :'.,1.t.,4,1::':0.I. Z:i .. .. --- , ,-, -.':'. · 6Jmt. EFi. I . - * ... * *1**81:9.- -:.... fi: -S, 1.¢f h: lot_; UNIVERSITY OF FLORIDA GAINESVILLE Numbers of the BULLETIN OF THE FLORIDA MUSEUM OF NATURAL HISTORY are published at irregular intervals. Volumes contain about 300 pages and are not necessarily completed in any one calendar year. F. WAYNE KING, EDITOR RHODA J. BRYANT, MANAGINGED/7DR Communications concerning purchase or exchange of the publications and all manuscripts should be addressed to: Managing Editor, Bulletin Florida Museum of Natural History; University of Florida; P. O. Box 117800, Gainesville FL 32611-7800; U.S.A This journal is printed on recycled paper. ISSN: 0071-6154 CODEN: BF SBA5 Publication date: December 12, 1995 Price: $2.50 PLIOCENE MAMMALS FROM INCHASI, BOLIVIA: THE ENDEMIC FAUNA JUST BEFORE THE GREAT AMERICAN INTERCHANGE Federico Anayal and Bruce J. MacFadden2 ABSTRACT A new, high-elevation (3200 m) mammalian local fauna is described from Communidad Inchasi, ca. 50 km SE of Potosi, Bolivia The fauna consists of 4 orders (Edentata, Rodentia, tLitopterng and tNotoungulata), 9 families, 10 genera, and at least 11 species. Ofthese, one new genus and two new species of notoungulates are described. This fauna contains two genera endemic to the Bolivian altiplano, tPosnanskytherium and tHypsitherium n. gen., whereas the remaining eight genera (tGiossotheridium, fProscelidodon, 'tplaina, fPlohophorus, fParaglyptodon, Shapalmatherium, Saviodon, and tPromacrauchenia) are referable to previously described genera from the Pliocene ofArgentina. The biochronology of the Inchasi mammals indicates either a: (1) Montehermosan/ Chapadmalalan (undifferentiated) age because the included tan are either restricted to the Montehermosan, Chapadmatalan, or span both mammal ages; or (2) Chapadmalalan age based on recent biostratigraphic redefinitions from classic localities in Argentina. Previous magneto- and biostratigraphic data indicate that the Inchasi beds and their contained mammalian fauna are middle Pliocene with an age range of between 3.3 and 4.0 myr ago. The Inchasi local fauna lacks any immigrant tan and thus represents an endemic fauna that occurred about 1 myr before the beginning ofthe Great American Interchange. RESUMEN Una nueva fauna local de mamif6ros es descripta para la Comunidad Inchasi, aproximadamente 50 kilometros al sudeste de Potosi, Bolivia, a una altura de 3200 m.s.n.m. Esta fauna comprende cuatro 6rdenes (Edentata, Rodentia, tLitopterna Y tNotoungulata), nueve familias, 10 g6neros y por 10 menos 11 especies. Se describe un g6nero nuevo y dos nuevas especies. Esta fauna tiene dos g6neros end6micos del altiplano Boliviano, tPosnanskytherium y tHypsitherium gen. n y los ocho restantes ('1Glossothendium, 1[Proscelidodon. 4'Plaina, 4[Plohophorus, 1[Paraglyptodon, 1~Chapalmatherium, 1~Caviodon y tPromacrauchenia) pertenecen a g6neros del Plioceno de Argentina Hay dos posibilidades para interpretar la biocronologia de los mamiferos de Inchasi: o (1) los f6siles guia indican una edad Montehermosense/Chapadmalalense (no dif*renciada) debido a que los taxones estan restringidos al Montehermosense, Chapadmatalense, 0 existieron durante las dos edadesjuntas; 0 (2) indican solo una edad Chapadmalalense en base a las investigaciones recientes en Argentina Estudios previos de la magneto- y bioestratigralia indican que los afloramientos de Inchasi pertenecen al Plioceno medio, con una edad entre 3.3 y 4 millones de afios. La mastofauna de Inchasi carece de inmigrantes norteamdricanos y ' The senior author is Jefe, Departamento de Paleontologia, Museo Nacional de Historia Natural Casilla 8706, Cota Cota, La Paz, Bolivia, and Cowtesy Curator. Department of Natural Sciences, Florida Museum of Natural History, University of Florida, P. O. Box 117800, Gainesville FL 32611-7800, U. S. A. Z Thejunior authoris Culator of Vertebrate Paleontology, Department of Natuial Sciences Florida Museum ofNatural History. University of Florida, P. 0. Box 1 17800, Gainesvile FL 3261 1-7800, U. S. A.,and Research Associate, Departamento de Palcontologia, Musco Nacional de Historia Natural La Paz, Bolivia. ANAYA F. and B. J. MACFADDEN. 1995. Pliocene mammals from Inchasi, Bolivia: The endemic fauna just before the Great American Interchange. Bull. Florida Mus. Nat Hist. 39(3):87-140. 88 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL 39(3) representa un intervalo aproximadamente de 1 mill6n de allos antes del comienzo del Gran Intercambio Americano. TABLE OF CONTENTS Introduction „„„-.--.--,--..-,-.-..„-.„„„„---.-----.----.--,...,.............. 88 Acknowledgements 89 Geological Setting and Previous Investifiinng 89 Methods and Abbreviations........................................................................................................................ 91 Systematic Paleontology 92 Order Edentata Cuvier, 1798 -Megatheriinae, indeterminant........................................................................................................... 92 -Glossotheridium chapadmatense (Kraglievich), 19?f 94 -Mylodontinae, indeterminant................................................................................................... 98 -Proscelidodon patrius (Ame*~01 1888 • eee~~e ---- m - I „„„„, m ... m .- ee~~eeeee - m .- m~~~m .... 100 -Plaina intermedia (,Ame$nol 1888 ,.............................................................. ~ ..'.. ~ ..........'............. 102 -Plohophorus sp 106 -Paragbptodon sp 109 Order Rodentia Bowdich, 1821 -Caviodon sp 110 -Chapalmatherium ¢f saavedrai Hoffstetter et at., 19*4 112 tCrder Litopterna Ameghino, 1889 -Promacrauchenia sp.................................................................................................................. 113 tCrder Notoungulata Roth, 1901 120 -Posnanskytherium desaguaderof Liendo, 1943............................................................................. 122 -Posnanskytherium inchasense, new specif 127 -Hypsitherium bolivianum, new genus anti .reie. 129 Disc,usion. 134 launal composition„ diversity, and alpha-leveltaxonon,y 134 _'aleoecology and paleoenvironmental reconstructions...................................................................... 135 Biogeography, Pliocene regional and continental correlations, and the problematic Montehermosan/Chapadmalalan interval 136 Summary and Conclusions..................................................~,..................-,... .„~-„-„„-....... 137 Literature Citp·,1 138 INTRODUCTION South America drifted as an island continent during most of the Cenozoic, carrying along with it an endemic biota. This isolation changed with the formation of the Panamanian Land Bridge and the consequent dry-land connection that allowed dispersal of many land mammals during the Great American Interchange (e.g. Stehli and Webb 1985). The main phase of this interchange began during the late Pliocene, about 2.5 myr ago, and continued through the Pleistocene until about 10,000 years ago when an extinction wave decimated the diversity of medium- to large-bodied mammals throughout the Americas. The fossil record of late Pliocene and Pleistocene land mammals in South America is very rich, with many localities recorded from numerous regions on that continent (Marshall et al. 1983; 1984). In contrast, relatively little is known of the ANAYA & MACFADDEN: PLIOCENE MAMMALS FROM BOLIVIA 89 endemic mammalian faunas during the late Miocene and early Pliocene just before the interchange. Consequently, the paucity of these earlier faunas has led to confusion about the biochronological characterization and distinctness of the Montehermosan and Chapadmatalan land mammal ages. Several Pliocene, pre- interchange mammal localities have been reported from Bolivia, e.g. at Ayo Ayo- Viscachani south ofLa Paz (Hoffstetter et al. 1971; Hoffstetter 1986), and although certain taxa have been described in detail (e.g. Hoffstetter et al. 1984), in most cases these important faunas have never been fully described. Recently a rich Pliocene, pre-interchange mammalian fauna has been discovered at Inchasi, about 50 km south of Potosi. This fauna offers significant potential to: (1) better understand the endemic mammals just before the Great American Interchange; (2) provide a further understanding of the Montehermosan and Chapadmalalan land mammal ages; and (3) further constrain the timing of the beginning of the Great American Interchange. The purpose ofthis study is to: (1) describe the mammalian fauna from Inchasi; (2) compare this fauna with other faunas of similar age in Bolivia and Argentina; (3) discuss the overall significance of this fauna with regard to faunal diversity, paleoecology, and land-mammal chronology. This report represents an amplification of a previous, preliminary description of this fauna (Anaya 1994). ACKNOWLEDGEMENTS The senior author gratefully acknowledges financial support from the Bryan Patterson Award of the Society ofVertebrate Paleontology in 1992. These funds allowed for one field trip to Inchasi and resulted in the collection of numerous important specimens that further increased the knowledge of this fauna. The authors thank Dr. Jaime Argollo of La Paz for showing us the Inchasi basin and for allowing us to pursue our studies there. Bernardino Mamani and Yuko