Andrewsarchus (/ˌændruːˈsɑːrkəs/) is an extinct genus of mammal that lived during the middle Eocene epoch in what is now Inner Mongolia, China. Only one species is usually recognized, A. mongoliensis, known from a single skull of great size discovered in 1923 during the expeditions of central Asia by the American Museum of Natural History (AMNH). Generally classified as a mesonychid since its original description, most recent studies recover it as an artiodactyl, in one study specifically, as a member of the clade Cetacodontamorpha, closely related to entelodonts, hippos and whales.