Bird feet and legs

The anatomy of bird legs and feet is diverse, encompassing many accommodations to perform a wide variety of functions.

Most birds are classified as digitigrade animals, meaning they walk on their toes rather than the entire foot. Some of the lower bones of the foot (the distals and most of the metatarsal) are fused to form the tarsometatarsus – a third segment of the leg, specific to birds. The upper bones of the foot (proximals), in turn, are fused with the tibia to form the tibiotarsus, as over time the centralia disappeared. The fibula also reduced.

The legs are attached to a strong assembly consisting of the pelvic girdle extensively fused with the uniform spinal bone (also specific to birds) called the synsacrum, built from some of the fused bones.