Anatomical review o Eira Barbara (Carnivora, Mustelidae) from the Quaternary of Southwestern Brazilian Amazonia

Most species of mustelids currently found in South America descend from North American immigrants that arrived during the Great American Biotic Interchange, following the rise of the Isthmus of Panama. However, previous works indicate that the genus Eira arrived in South America before this event, through an island bridge in Central America. The tayra Eira barbara (Mustelidae, Carnivora), the only species of the genus, currently has a wide geographic distribution, from Mexico to northern Argentina. Here, we redescribe a fossil of E. barbara collected close to the Municipality of Marechal Thaumaturgo, Acre State, Brazil. The southwestern Brazilian Amazonia is mostly characterized by the older sediments of Solimoes Formation (Neogene deposits), although on the riverbanks of the Upper Jurua River a typical Quaternary vertebrate fauna is also found, mainly represented by fossil mammals. The specimen UFAC PV-36 is a right hemimandible with the p4 preserved in situ, and it was compared to fossil and extant specimens of E. barbara, as well as with other carnivorans. The review of the fossil record shows that this taxon is restricted to the Quaternary of Brazil, in the states of Bahia, Minas Gerais and Acre, and of Argentina, in the Entre Rios Province. In this way, our study contributes to a better understanding of the origin and distribution of the genus in the Quaternary of South America.