New records of caviomorph rodents (Ctenohystrica, Hystricognathi) from the Early Miocene of Sacanana locality (Patagonia, Argentina)

Abstract

The Sacanana locality, from the Early Miocene (Colhuehuapian South American Land Mammal Age) of the Sarmiento Formation (Chubut Province, Argentina), offers a notable fossil record of mam- mals, including primates, rodents, ungulates and metatherians. The caviomorph fauna is primarily known through a few well-preserved specimens, while its general diversity remains largely unex- amined. Here we report new fossil rodents from Sacanana, collected with strict stratigraphic control, including the first mention of Perimys erutus and Perimys intermedius, a skull fragment of Chinchilloidea indet. and a specimen of the known Soriamys ganganensis. This contribution increases the diversity of caviomorphs in the locality, from four genera and four species to five genera and six species. In this way, Sacanana is the third Colhuehuapian rodent fauna from the Argentinian Patagonia with the greatest taxonomic diversity after Bryn Gwyn and Gran Barranca. The presence of Perimys in Sacanana extends the geographic distribution of the genus within the Colhuehuapian SALMA. It also provides a new biochron for Perimys erutus and P. intermedius, previously known for the Pinturan and Santacrucian SALMAs (late Early Miocene).