The skeleton of Gazinocyon vulpeculus gen. et comb. nov. and the cladistic relationships of Hyaenodontidae (Eutheria, Mammalia)

ABSTRACT

Our general understanding of hyaenodontid phylogeny and classification, particularly the division between the phylogenetically and morphologically primitive Proviverrinae and the derived Hyaenodontinae, has been fairly stable since Matthew laid down its framework in the early 20th century. However, a wealth of material described since that time allows Matthew's conclusions to be re-examined. Adding to that wealth is a new skeleton of Gazinocyon vulpeculus gen. et comb. nov. The postcranium of this specimen indicates that this animal was probably incipiently cursorial. The hindlimb morphology suggests that motion in the ankle was restricted to a parasagittal plane and that the animal was digitigrade. The forelimb is less completely preserved, making its functional ability more difficult to assess. Cladistic analysis suggests that Gazinocyon was related to a clade containing Eurotherium, Propterodon, Hyaenodon, and “Pterodon” hyaenoides. It also suggests that Hyaenodontinae (containing Pterodon, Hyainainlouros, Hyaenodon, and “Pterodon” hyaenoides, among others) is diphyletic. Pterodon and Hyainailouros appear to be only distantly related to Hyaenodon, losing the metaconid/(the diagnostic character of Hyaenodontinae) independently of the latter genus. Hyaenodontinae is restricted and Pterodontinae subfam. nov. is defined to reflect this hypothesis.