The fossil record of the short-faced bears (Ursidae, Tremarctinae) from Venezuela. Systematic, biogeographic, and paleoecological implications

Abstract

The first record of a Tremarctinae bear in Venezuela was made by ROYO y GOMEZ in 1960. Since then, three new specimens from two localities have been collected but not reported. The purpose of this contribution is to discuss the taxonomy, biostratigraphy, and biogeographic implications of these records. The bear genera included in the subfamily Tremarctinae are distributed exclusively in America. In South America only one fossil genus is recorded, Arctotherium, comprising five species: A. angustidens, restricted to the Ensenadan (early - middle Pleistocene) of Argentina and Bolivia; A. vetustum, recorded only in the Bonaerian (middle Pleistocene) of Brazil and Argentina; two Bonaerian and Lujanian (middle Pleistocene - early Holocene) species, A. bonariense (recorded only in Argentina), and A. tarijense (occurring in Argentina, Bolivia, Uruguay and Chile); and A. wingei, recorded with certainty only in the Lujanian (late Pleistocene - early Holocene). After the present study we conclude that (1) A. wingei is the only species recorded in Venezuela, and (2) all known specimens have Lujanian provenance. Outside Venezuela, this species is recorded from Bolivia and Brazil but without precise stratigraphic data. Although A. wingei is one of the most plesiomorphic Arctotherium species, it has not been recorded in sediments older than late Pleistocene. This could be interpreted as species preference for low latitude tropical or subtropical environments, which are poorly represented in early Pleistocene continental sediments.