A new finding in the Blancan of the El Salvador indicates the probable dating of the Tremarctinae’s (Ursidae, Carnivora) entrance to South America.

LEOPOLDO HECTOR SOIBELZON; TARTARINI, V. B.; ROMERO, M.; HUZIER AGUILAR, D.

Montevideo

Congreso; V Congreso Uruguayo de Geología.; 2007

We present here a deciduous tooth founded in the Blancan (Pliocene) at Río Tomayate locality (República de El Salvador). After the study, here presented, we assigned this tooth to Arctotherium (South American short-faced bears) on the basis of its morphology and size. Carnivores like many other taxa entered South America from North America in the event called “Great American Biotic Interchange” (GABI). We think that this individual was being part of the stock that entered South America and resulted in a new and endemic genus: Arctotherium (South American short-faced bears). Arctodus and Arctotherium are sister groups and conform the “short-faced bears clade”. The oldest record of a short-faced bear in South America corresponds to Arctotherium angustidens which is first recorded in the Ensenadan (Lower to Middle Pleistocene) of the Pampean Region of Argentina; 5200 km far from Panamian Isthmus. Among Ensenadan sediments the oldest ones are those of “las toscas del Río de La Plata” locality (Pampean Region). The age of these sediments is 1Ma and they correspond to Chron C1r2r. In the northern portion of South America (Venezuela) Arctotherium was recorded only in the Upper Pleistocene. Thus, up to day, there is no evidence about the first bears that entered South America.