First record of Dasyproctidae (Rodentia) in the Pleistocene of Argentina. Paleoclimatic implication

Plesiaguti totoi gen. et sp. nov., the first member of the Dasyproctidae recorded in the Pleistocene of Argentina, is described. It comes from the coastal cliffs of Necochea, on the southern coast of Buenos Aires Province. Taking into account its tooth morphology, pentalophodont and almost brachyodont, it represents one of the most primitive dasyproctids. The morphology of the occlusal surface suggests that P. totoi is more closely related to the living representatives of the family than to extinct species of the Oligocene-Miocene of Argentina. This phylogenetic hypothesis, plus the fact that dasyproctids vanished from these latitudes by at least the early Pliocene, argues that P. totoi is an immigrant to Buenos Aires Province. Its presence reinforces the idea of the existence of one or more warm pulses during the Pleistocene that permitted the southward migration of Brazilian fauna. (C) 2002 Elsevier Science B.V. All rights reserved.