locomotion means walking with the podials and metatarsals
flat on the ground.
are examples of plantigrade species; in humans, the podials and metatarsals constitute the sole of the foot. Other plantigrade species include raccoons
The members of the extinct mammalian order Creodonta displayed plantigrade locomotion. This may have led to their extinction as they were supplanted by the more efficient Carnivora. It seems that at least some pterosaurs and lizards were plantigrade as well.