The Southfork Local Fauna, Cypress Hills Formation, Cypress Hills Plateau, southwestern Saskatchewan, is distinctly older than the nearby Calf Creek Local Fauna. Co-occurrence at Southfork of Hyracodon petersoni, Brachyhyops viensis, Leptomeryx cf. L. yoderi, and Leptomeryx cf. L. blacki indicates biostratigraphic correlation low in the early Chadronian. Presence of Oligocene local faunas of different ages strengthens the concept of a faunal succession in the Cypress Hills Formation, and emphasizes the importance of considering Cypress Hills assemblages locality by locality.