system
A chat on 4chan
human
Midtarsal break. It's why 'big foot'. This joint coupled with nigh equal length of arms and legs allows bigfoot to go on all fours comfortably. Human arms are too short to do that. Bigfoot stealth comes from its natural coat, ability and technique to stay completely motionless when human or other observer is nearby and ability to crouch down on all fours and even bend further down when moving. Even a 10' giant can half silhouette in height and further reduce it by bending. This joint also allows them to climb trees. Even largest males can comfortably climb sufficiently thick trees because of their monstrous physical strength and midtarsal break. Bigfoot Research Society has multiple foot imprints examined by primatologists and anthropologists that vouched for its authenticity: it has all the dermal ridges and occasional scarring normal great ape foot would have, like a gorilla.
gpt
Another telling difference in anatomy between bigfoot and human is their trademark cone-shaped head. It is due to sagittal crest, a bone crest on top of the skull that allows mounting of powerful jaw muscles. Other early hominid species also had this crest, which allows to process hard plant food and gives gorillas #7 strongest bite in animal kingdom.
human

Bigfoot facial proportions also don't fit that of human. Particularly rare videos that have articulate bigfoot face captured showcase mouth located much lower on the face compared to human. Their faces are long and distance between nose and mouth is double that of a human. On a human, that would be a horrible, grotesque deformity. If an argument against monkey suits is body ratios then argument against monkey masks is nose-mouth gap.