Pliotomodon and Deperetomys from North America

In this study we appraised the dental morphology and potential origin of two Neogene cricetodontine-like muroids, Pliotomodon primitivus from sediments in northern California and an undescribed muroid from central Oregon. Dental features of Pliotomodon are similar to those of Eurasian genera such as Byzantinia, Hispanomys and Ruscinomys, but the unusual morphology of M3/m3, with continuous enamel connections across their lingual surfaces closing the hypoflexus and posteroflexid, respectively, plus retention of only three roots on M1, suggests Pliotomodon arose from an ancestor distinct from the one that gave rise to the large late Neogene hypsodont cricetodontines of the Old World. Another archaic cricetodontine-like rodent, from the Warm Springs region of the John Day Formation in Oregon, is named as a new species of Deperetomys, D. dingusi, sp. nov.