What specific part of the hand provides support during terrestrial knuckle-walking locomotion?

Answer

The middle knuckles

Knuckle-walking is the primary method of movement utilized by Western lowland gorillas across the forest floor, representing a specialized form of quadrupedal locomotion. This movement is characterized by the gorilla supporting the majority of its powerful upper body weight not on the flat of the hand, but by resting it directly upon the middle knuckles of their forelimbs. The palms are consequently turned inward during this posture. This adaptation is supported by their long, muscular forelimbs and strong fingers, distinguishing their ground movement from many other primate species.

What specific part of the hand provides support during terrestrial knuckle-walking locomotion?
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