Abstract

Late Oligocene caviomorphs represent one of the most important early adaptive radiations of this group of rodents. They show a high taxonomic diversity and a wide geographic distribution, with those found in the upper Oligocene of Salla (Bolivia) and Patagonia (Argentina) being particularly diverse. However, caviomorphs from the Deseadan South American Land Mammal Age in other latitudes are still scarcely known. In this contribution, we describe new caviomorph rodents from the Deseadan levels of Quebrada Fiera locality (Mendoza Province; central-western Argentina) and evaluate their systematic and paleobiogeographic significance. The taxonomic composition of the caviomorphs from Quebrada Fiera reveals a complex biogeographic history, as we recognize one endemic Cavioidea (Asteromys puelche sp. nov.) and two Chinchilloidea: one with Patagonian affinities (Cephalomys sp.) and another with a wide distribution in South America (Incamys bolivianus). Asteromys puelche sp. nov., shows closer phylogenetic affinities with the Bolivian A. bolivianus than with the Patagonian A. punctus. These rodents, in common with the whole mammalian association from Quebrada Fiera, show a mix of endemic taxa and others shared with higher and lower latitudes.