New Early Eocene Mammalian Fauna From Western Patagonia, Argentina.

TEJEDOR, M. F.; GOIN, F. J.; GELFO, J. N.; LOPEZ, G.; BOND, M.; CARLINI, A. A.; SCILLATO-YANÉ, G. J.; WOODBURNE, M. O.; CHORNOGUBSKY, L.; ARAGON, E.; REGUERO, M.; CZAPLEWSKI, N.; VINCON, S.; MARTIN, G.; CIANCIO, M. R.

AMERICAN MUSEUM NOVITATES

PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY

Lugar: NEW YORK, NY; Año: 2009 p. 1 - 43

0003-0082

ABSTRACTTwo new fossil mammal localities from the Paleogene of central-western Patagonia arepreliminarily described as the basis for a new possible biochronological unit for the early Eocene of Patagonia, correlated as being between two conventional SALMAs, the Riochican (older) and the Vacan subage of the Casamayoran SALMA. The mammal-bearing strata belong to the Middle Chubut River Volcanic-Pyroclastic Complex (northwestern Chubut Province, Argentina), of Paleocene-Eocene age. This complex includes a variety of volcaniclastic, intrusive, pyroclastic, and extrusive rocks deposited after the K-T boundary. Geochronological data taken from nearbyvolcanic deposits that underlie and overlie the mammal-bearing levels indicate that both faunas are of late early Eocene age (Ypresian-Lutetian boundary). In addition to more than 50 species of mammals, including marsupials, ungulates, and xenarthrans, two lower molars are the oldestevidence of bats in South America. Paleobotanical and palynological evidence from inferredcontemporary localities nearby indicate subtropical environments characterized by warm andprobably moderately humid climate. Remarkably, this new fauna is tentatively correlated withEocene mammals from the La Meseta Formation in the Antarctic Peninsula. We conclude that the two localities mentioned above are part of a possible new biochronological unit, but the formal proposal of a new SALMA awaits completion of taxonomic analysis of the materials reported upon here. If the La Meseta fauna is correlated biochronologically to western Patagonia, this also suggests a continental extension of the biogeographic Weddelian Province as  far north as centralwestern Patagonia.American Museum Novitates novi-577-00-01.3d 4/12/08 10:51:35 1 Cust # 577