Digitigrade

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A digitigrade is an animal that stands or walks on its digits, or toes. Digitigrades include walking birds (what many assume to be bird knees are actually ankles), cats, dogs, and most other mammals, but not humans, bears, and a few others (cf. plantigrade, unguligrade). They are generally quicker and move more quietly than other mammals.

While humans usually walk with the soles of their feet on the ground, i.e. plantigrade locomotion, digitigrade animals walk on their distal and intermediate phalanges. Digitigrade locomotion is responsible for the distinctive hooked shape of dog legs.

There are anatomical differences between a plantigrade and digitigrade limb. Digitigrade animals have relatively long carpals and tarsals, and the bones which would correspond to the human ankle are thus set much higher in the limb than in a human. This effectively lengthens the foot, so much so that a digitigrade animal's "hands" and "feet" are often thought to correspond only to what would be the bones of the human finger or toe.