Mesonychid
 Mesonychia (Middle Claws) is an extinct taxon of medium to large-sized carnivorous digitigrade ungulates related to the cetartiodactyls. Mesonychids first appeared in the Early Paleocene went into a sharp decline at the end of the Eocene and died out entirely when the last genus Mongolestes became extinct in the Early Oligocene.Mesonychids probably originated in Asia where the most primitive mesonychid Yangtanglestes is known from the early Paleocene.