Registro de Eoviscaccia (Rodentia, Chinchillidae) en estratos colhuehuapenses de Patagonia, Argentina

KRAMARZ, A.

AMEGHINIANA

Asociación Paleontológica Argentina

Lugar: Buenos Aires; Año: 2001 vol. 38 p. 237 - 242

0002-7014

New dental remains of a chinchillid rodent from the Colhuehuapian Age (lower Miocene) of Chubut province, Argentine, are described. These remains are tentatively referred to Eovicaccia australis, species only known by two isolated teeth from the Deseadan Age. The unworn and little worn cheek teeth show S-shape occlusal morphology with four crest in the uppers and three in the lowers, and the enamel is continuous. In little more worn teeth a bilobated configuration is acquired, a thin cement deposit between the laminae appears, and the enamel covering becomes discontinuous. The M3 has a rudimentary third lamina. The first description of the deciduous dentition of a chinchillid is given. These new materials confirm that E. australis is more derived than E. boliviana (Deseadan Age from Bolivia) but more primitive than Prolagostomus and Pliolagostomus (Santacrucian and Friasian Ages), due to its degree of  hipsodonty, enamel reduction, development of a laminar dental pattern and of the third lamina in the M3.