The bird's leg has the typical vertebrate pattern of femur, tibia, and fibula.

Extensive fusion in the lower leg aids in absorbing the shock of take-off, landing, running or hopping. The tibia is fused with the upper bones of the foot to form the tibiotarsus. The remnant of the fibula is toothpick-like.

The lower bones of the foot are fused and elongated to form the tarsometatarsus, which provides extra lever length that partially absorbs the force of footfalls, and gives extra leverage to push forward in running or in taking off.

The only joint that is visible in a living bird is the backward-pointing ankle. Feathers hide the forward-facing knee.

The hallux of the bird is homologous to the human big toe.

Birds are digitigrade, meaning they walk on their toes instead of on their feet.

Avian Skeletal Adaptations Main Page /Pectoral Girdle /Pelvic Girdle /Thorax
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