Triisodontidae

Triisodontidae (literally "three equal teeth") is an extinct, possibly invalid family of mesonychian placental mammals. Most triisodontid genera lived during the early Paleocene in North America, but the genus Andrewsarchus (if it is a mesonychian, and not an artiodactyl) is known from the late Eocene of Asia. Triisodontids were the first relatively large predatory mammals to appear in North America following the extinction of the dinosaurs. They differ from other mesonychian families in having less highly modified teeth.

Because of their comparatively simpler teeth, the Triisodontids are regarded as basal mesonychids. A recent study found them to be a paraphyletic assemblage of stem-mesonychians.