Answer to Question #119101 in Evolution for Jack

Question

What are the structural differences between the hind foot of a dog, goat and human.

Answer 1

The hind foot of a dog has a digitride orientation. The vertical columnar orientation of the proximal ones, which articulate with the distal foot structure that are arranged in a quasi vertical columnar orientation is well designed to transmit loading during weight bearing contact of the skeleton with the ground.

The hind limbs ( pelvic limbs) of the goats on the other hand consist of the pelvic girdle, thigh and lower limb made of the tarsus, metartarsals and phallanges, just like the hind limb of the the human. Goats have a radial leg spring which is lesser in the hind limbs than the fore limbs which helps in sprinting of the goat during evasion of predators.

Humans have a unique plantigrade alignment which results in a distal limb structure that adapts to a variety of conditions. The limb has less tarsal bones that are shaped and aligned to adapt and transmit large loads during early stages of stance.