An extinct order of quadrupedal eutherian land mammals known from the early Cenozoic deposits of the Rocky Mountain intermontane basins of western North America and, based on a single tooth of Ectoganus gliriformis, from early Cenozoic rocks in South Carolina. The nine known genera of taeniodonts are classified into two families: (1) the medium-size (5–15 kg or 11–33 lb), relatively primitive, omnivorous conoryctids (Schochia, Onychodectes, and Conoryctella, early Paleocene; Huerfanodon and Conoryctes, middle Paleocene); and (2) the larger (15–110 kg or 33–243 lb) and more advanced stylinodontids (Wortmania, early Paleocene; Psittacotherium, middle Paleocene; Ectoganus, late Paleocene to early Eocene; and Stylinodon, middle Eocene).