Los Xenarthra (Mammalia) del Ensenadense (Pleistoceno inferior a medio) de la Región Pampeana (Argentina)

Abstract

Xenarthra is a monophyletic group, characterized by a particular skeletal architecture, different to other placental mammals. Its current distribution is exclusively Neotropical; however, the fossil record indicates a greater distribution. The aim of this paper is to provide an updated list of the Xenarthra of the lower to middle Pleistocene (Ensenadan Stage) of the Pampean Region (Argentina). The most conspicuous anatomical features that allowed the taxonomic identification of fossil remains, especially those of particular biostratigraphic interest, are also briefly described and figured here. We studied more than 700 fossil remains mostly housed in palaeontological collections of Argentina. The study of these specimens (from the Pampean Region), revealed that during the Pleistocene there were marked variations in the composition and distribution of the faunas in general and particularly in xenarthrans. This situation was closely related to the Great American Biotic Interchange and climatic oscillations occurring in the Pleistocene. Thus, the Ensenadan fossil record of xenarthrans consists on exclusive taxa and numerous cases of first and last records. Finally, we expect that this contribution provide a starting point for future contributions in respect of the Pleistocene fauna, not only from the Pampean Region, but also from the rest of Argentina and South America.