For the first half of the Cenozoic, members of the order Creodonta were the predominant terrestrial carnivores in North America, Eurasia, and Africa. Creodonts exploited many of the same adaptive zones as later members of the Carnivora and Marsupialia, and they exhibit many of the same morphologies. Although they had a wide distribution and great ecologic importance, the phylogeny and major locomotory and feeding adaptations of creodonts remain largely unstudied. This study will be the first comprehensive assessment of creodont phylogeny and evolution in the context of phylogenetic systematics. It will address the questions of creodont monophyly, their relationship to the Carnivora, their phylogenetic position within Eutheria, and the position of several problematic taxa within Creodonta. Furthermore, this phylogenetic information will be used to examine the origin of morphologies convergent with those seen in other carnivorous mammals. Creodonts had three relatively separate radiations. These, along with the radiations of Carnivora and carnivorous marsupials, provide an excellent chance to look at the phenomena of convergent evolution and community structure in terrestrial ecosystems of the Tertiary. Data will come from original analysis of museum specimens and from the published literature. In the phylogenetic analysis dental, cranial, postcranial, and inferred anatomical characters will be used.