Mesonychia ("middle claws") is an extinct taxon of small- 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.

Mesonychia ("middle claws") is an extinct taxon of small- 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.