Extinct ones include Ancylopoda and Mesonychids.
Ungulates are characterised by reduced canine teeth, bunodont molars (molars with low, rounded cusps); an astragalus (one of the ankle bones at the end of the lower leg) with a short, robust head. Ungulates diversified rapidly in the Eocene, but are thought to date back perhaps as far as the Late Cretaceous.