A new genus and species of paramyine ischyromyid, Metaparamys dawsonae, is described from the Chadronian of Wyoming. The new genus is distinguished from other paramyines in having the ectolophid on lower molars complete between protoconid and hypoconid and without a mesoconid, hypocone and metaconule on upper molars relatively larger than in Paramys, lower incisor wide with convex anterior surface, and masseteric scar on mandible more anterior than in other paramyines. The Uintan species Paramys compressidens Peterson is also assigned to Metaparamys. The Bridgerian P. delicatior Leidy appears to be a likely ancestor for Metaparamys based on the cross-sectional shape of the lower incisor. The occurrence of M. dawsonae is one of the latest records of a paramyine rodent in North America.