Ursidae, Tremarctinae) from Venezuela

460-soibelzon-16.4. 28.06.2007 18:40 Uhr Seite 287 (Schwarz Bogen)

N. Jb. Geol. Paläont. Abh. 2007, vol. 244/3, p.287–298, Stuttgart, June 2007, published online 2007

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

Leopoldo H. Soibelzon, La Plata and Ascanio D. Rincón, Caracas With 4 figures and 8 tables

SOIBELZON, L. H. & R INCÓN, A. D. (2007): The fossil record of the shor t-faced bears (Ursidae, Tremarctinae) from Venezuela. Systematic, biogeographic, and paleoecological implications. – N. Jb. Geol. Paläont. Abh., 244: 287–298; Stuttgart.

Abstract: The first record of a Tremarctinae bear in Venezuela was made by ROYO y GÓMEZ in 1960. Since then, three ne w specimens from tw o localities have been collected b ut not repor ted. The purpose of this contrib ution is to discuss the taxonom y, biostratigraphy, and bio geographic 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 (earl y – 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 – earl y Holocene) species, A. bonariense (recorded only in Argentina), and A. tarijense (occurring in Argentina, Bolivia, Uruguay and Chile); and A. wingei, recorded with cer tainty only in the Lujanian (late Pleistocene – earl y Holocene). After the present study w e 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 inter preted as species preference for lo w latitude tropical or subtropical environments, which are poorly represented in early Pleistocene continental sediments.

Key words: Ursidae, Tremarctinae, Arctotherium wingei, South America, Muaco, Guácharo Ca ve, Venezuela, Pleistocene.

1. Introduction American species: A. angustidens, restricted to the Ensenadan (early – middle Pleistocene), A. vetustum, The bear genera that constitute the subf amily Tre- recorded only in the Bonaerian (middle Pleistocene), marctinae (Carnivora: Ursidae) are distrib uted ex- two Bonaerian-Lujanian (middle Pleistocene – earl y clusively in America. Of these, (1) Plionarctos is Holocene) species, A. bonariense, and A. tarijense recorded from late Miocene to earl y Pliocene of (SOIBELZON 2004), and A. wingei, recorded with North America with tw o species, P. edensis and P. certainty in the Upper Pleistocene only (as established harroldorum; (2) Arctodus contains two North Ameri- in this paper); and (4) Tremarctos with two species, can late Pliocene – Pleistocene species, A. pristinus T. floridanus from the late Pliocene and Pleistocene of and A. simus; (3) Arctotherium comprises five South North America, and the onl y living tremarctine, T.