A new record of Megatherium (Folivora, Megatheriidae) in the late Pliocene of the Pampean region (Argentina)

Abstract

The genus Megatherium includes nearly ten species that are distributed along the Pleistocene of South America. In contrast with the abundant and geographically widespread Pleistocene record, remains of Pliocene Megatherium are restricted to a single and poorly known species from the highlands of Perú. The aim of the present contribution is to describe a skull referable to the genus Megatherium coming from Late Pliocene beds at the San Eduardo del Mar locality, Buenos Aires Province, Argentina. This constitutes the first undoubted record of Megatherium from the Pliocene of Argentina, and one of the oldest records for the genus. This finding blurs previous biogeographical proposals sustaining that the genus originated in the High Andes and later dispersed to the lowlands. On the contrary, present finding, together with the record of coeval Megatherium species in the Pleistocene of the Argentine Pampas, suggests a more complex palaeobiogeographical scenario and indicates that the diversity of lowland Pliocene megatheriines is still underrepresented.