Deciduous dentition of didymictis (Carnivoramorpha: Viverravidae): Implications for the first appearance of "creodonta"

Abstract

Deciduous teeth of Carnivoramorpha can differ substantially from their permanent structural and functional counterparts, particularly dP4. As a consequence, isolated carnivoramorphan deciduous teeth have repeatedly been misidentified as permanent teeth of different, often unrelated taxa. Due in part to this potential for misidentification, the deciduous dentitions of basal carnivoramorphans remain poorly documented. This study describes and illustrates the 1st known deciduous premolars of a member of the basal carnivoramorphan family Viverravidae, with dP34 and dp34 of the early Eocene Didymictis protenus (Cope, 1874) documented by specimens associated with permanent teeth. The morphology of these specimens permits a reconsideration of the affinities of 2 mid-Paleocene taxa, Deltatherium durini Van Valen, 1978 and Prolimnocyon macfaddeni Rigby, 1980, that have been proposed to represent the earliest known members of the family Hyaenodontidae and the order "Creodonta." Both species are founded on viverravid deciduous premolars. Reidentification of these taxa eliminates the Paleocene record of hyaenodontids from North America. © 2012 American Society of Mammalogists.