Animal knees vs. human knees

[Colibri]

@GuanoLad

But effectively the actual joint directional equivalent on each leg, is the foreleg’s elbow to the back leg’s ankle. The forward motion is achieved by having the two sets of limbs effectively jointed in the same ‘<’ formation.

Not at all. This depends entirely on the leg proportions of the animal. Some have elbows and knees at the same level, others don’t. Differences in the direction of flexion of a limb at a particular point above the ground are achieved by lengthening or shortening the limb bones, not by changing the direction of flexion of the joint itself.