Cavioids, Chinchilloids, and Erethizontoids (Hystricognathi, Rodentia, Mammalia) of the Early Miocene Pampa Castillo Fauna, Chile

Caviomorph rodents became important components of South American faunas after their Eocene arrival from Africa. Here we describe the cavioid, chinchilloid, and erethizontoid caviomorphs early Miocene Pampa Castillo fauna southern Chile. This fauna's age location make it key for resolving outstanding biostratigraphic questions concerning Patagonian fossiliferous strata. Each four major caviomorph clades (“superfamilies”) is represented in fauna, three whose members are detailed here: cavioids (3 genera; 3 species), chinchilloids 6 erethizontoids (2 2 species). Abundantly taxa, e.g., Neoreomys australis, Perimys erutus, Prolagostomus pusillus, corroborate previous work assigning to Santacrucian Land Mammal “Age” (SALMA; inclusive “Pinturan”). Several including Eosteiromys, intermedius, sp. nov.?, also found lower middle Pinturas Formation (lmPF) but not “core” (from Santa Cruz [SCF] along Río Atlantic coast), suggesting a distinctive resemblance between lmPF rodents. Some authors consider form basis “Pinturan” SALMA or subage, considered slightly predate core faunas, which has yet be formally recognized. The taxonomic composition rodent Castillo, as well relative abundance data, indicated paleoenvironment intermediate closed forests mosaic open habitats SCF.