Giant rodents from the Neotropics: diversity and dental variation of late Miocene neoepiblemid remains from Urumaco, Venezuela

Abstract

Caviomorphs constitute a large evolutionary radiation of South America rodents, exhibiting a wide range of body size and ecomorphological disparity. The geological history of caviomorphs has been recorded mainly from high latitudes, besides isolated discoveries from the Neotropics. The late Miocene fauna from Urumaco, Venezuela, is noteworthy for its location and for preserving the giant rodent Phoberomys pattersoni. Previous studies of isolated postcranial remains suggested that the rodent diversity from Urumaco was higher than is currently recognized. Based on new remains we document dental variation that indicates the presence of at least two giant rodent taxa in Urumaco, including Neoepiblema. Quantitative analysis of dentition of the different neoepiblemid species supports the differentiation between Neoepiblema and Phoberomys and suggests that several recognized species of Phoberomys could represent different ontogenetic stages of one or few taxa within the genus.