Spur (zoology)

A spur is an outgrowth of bone covered in a sheath of horn found in various anatomical locations in some animals. Unlike claws or nails, which grow from the tip of the toes, spurs form from other parts of the foot, usually in connection with joints where the toes meet the foot or the foot meets the long bones.^[1] Spurs are most commonly found on the hindfeet, though some birds possess spurs at the leading edge of the wings.^[2]