Un primitivo Notonychopidae (Litopterna) del Paleoceno inferior de Punta Peligro, Chubut, Argentina

Abstract

The discovery of a new ungulate species, Requisia vidmari gen. nov., nov. sp. in the lower Paleocene of Punta Peligro, Chubut (Argentina) represents the earliest known record of Litopterna. The dental morphology of this new genus is very similar to that known for Notonychops powelli Soria, 1989, differing mainly by its more primitive M3, which is less elongated and less selenodont. Requisia vidmari, toegher with Wainka tshotshe Simpson, 1948, can be included in the family Notonychopidae, which appear to represent an ancestral grade in the evolution of Litopterna. Because cladogenesis of South American ungulates clearly took place prior to the Punta Peligro fauna and was apparently rapid, phylogenetic interpretation is difficult.