Calcaneus
Short bone, part of the appendicular skeleton
Also known as: Heel bone
Classification
Short bone, part of the appendicular skeleton
Dimensions
Varies widely by species, generally blocky and elongated with a prominent heel extension for muscle attachment.
Key Features
Blocky, irregular shape with a prominent elongated back end, a rough surface where strong tendons attach, and distinct smooth notches where it fits together with neighboring ankle bones.
Similar Bones
Can be confused with other large ankle or wrist bones like the astragalus. The calcaneus is easily told apart by its distinctive long heel extension designed for muscle leverage.
Across Species
In plantigrade animals like humans and bears, the calcaneus forms a long flat heel on the ground. In cursorial mammals like horses and deer, it is elevated high off the ground as part of a spring-loaded leaping and running mechanism, creating the hock joint.
Evolutionary History
Evolved from early tetrapod ankle bones to provide increased leverage for leg muscles, shifting from sprawling lizard-like locomotion to upright, energy-efficient striding and running.
Photography Tips
Place the bone on a neutral, solid-colored surface with a coin or ruler for scale. Take shots from the top, bottom, and side views using soft, natural side-lighting to highlight the surface texture and contours.