Carnivoramorphans and creodonts are two groups of ancestrally carnivorous mammals that both emerged in the Paleocene (66-56 Ma) of North America. During the Eocene (56-33.9 Ma), carnivoramorphans radiated into some of the taxonomic groups we still see today, while creodont diversity declined until the group went extinct in North America during the Oligocene (33.9-23 Ma) and worldwide during the Miocene (23-5.3 Ma). In this thesis, I test the hypothesis that competition with carnivoramorphans may have led to the extinction of the creodonts in North America by examining changes in niche overlap between the two groups from the start to the end of the Eocene. My results do not support the competition hypothesis, instead suggesting that creodonts were hyperspecialized and un-equipped for the dramatically different environments of the late Eocene and early Oligocene.