Mesonychia ("middle claws") is an extinct taxon of small- to large-sized carnivorous 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. They resembled wolves, albeit superficially. Early mesonychids probably walked on the flats of their feet (plantigrade), while later ones walked on their toes (digitigrade). These later mesonychids had hooves, one on each toe, with four toes on each foot.