digitigrade

Digitigrade refers to a mode of terrestrial locomotion in which an animal bears weight primarily on its digits—the toes and the distal metatarsals—with the heel raised above the ground. This contrasts with plantigrade locomotion, where the entire foot contacts the substrate, and unguligrade locomotion, where weight is borne on the tips of the digits, usually the hooves. The term derives from Latin digitus (finger, toe) and gradus (step).

In digitigrade animals, the hind limb and foot are arranged to maximize stride length and speed. The elevated heel allows the leg to swing through a longer arc, and the elongated metatarsal and phalangeal segments provide leverage and propulsion. Claws or nails on the digits often extend the contact surface and aid traction. The stance can enhance sprint performance and efficiency on firm ground, though it may reduce stability on soft surfaces or uneven terrain.

Digitigrade locomotion is widespread among mammals and birds. In mammals, it is common in many carnivorans and other terrestrial species; in birds, the hind limbs are primarily digitigrade, with weight borne on the toes. Among extinct groups, many theropod dinosaurs exhibited digitigrade hindlimbs, a trait inherited by modern birds. In the broader context of limb evolution, digitigrade posture sits alongside plantigrade and unguligrade strategies, reflecting trade-offs between speed, energy use, and habitat.