New insight of the genus Cephalomyopsis (Caviomorpha, Cephalomyidae): Systematic revision and paleobiogeographical implications

Abstract

Cephalomyopsis hypselodontus is a member of the family Cephalomyidae, originally described based on some isolated remains from the Colhuehuapian locality of Bryn Gwyn (Chubut Province, Argentina). Some specimens from the Deseadan localities of Cabeza Blanca (Chubut Province, Argentina) and Lacayani (La Paz Department, Bolivia), first described as Cephalomyidae morphotype 2 and 3, were later included in the genus. Also, a specimen found in Arroyo Avalos (Corrientes Province, Argentina) was included in the genus, but a taxonomic revision at the species level was never conducted. In this contribution, I revise all the specimens included in the genus, as well as new specimens found in Bryn Gwyn. The new specimens include the most juvenile teeth known so far and the first complete upper tooth row known for the genus. As a result, I define a single species for the genus and discuss the implication of this new systematic proposal. The species has a wide geographical distribution and a long biochron, the longest among cephalomyids. Finally, I discuss the dissimilarities between different localities in Argentina and Bolivia and the implications in the evolutionary history of Cephalomyidae and Chinchilloidea.