Metapodial (Cannon Bone) with attached phalanges
Long bone of the appendicular skeleton
Also known as: Lower leg bone and foot bones
Classification
Long bone of the appendicular skeleton
Dimensions
Varies widely by animal species, typically ranging from several inches to over a foot in length, characterized by a long, straight shaft connecting sturdy joint ends.
Key Features
Features a very straight, stout central shaft with smooth surfaces, flaring at both ends into broad, blocky joint structures, often found connected to smaller toe bones at the lower end.
Similar Bones
Can be easily confused with upper leg bones like the femur or humerus, but is distinguished by its much straighter, narrower shaft and lack of a spherical ball joint at the top end.
Across Species
In hoofed animals like deer and cattle, these lower leg bones are heavily fused and elongated to act as additional spring-like levers for high-speed running. Horses walk on a single, highly specialized digit, whereas cloven-hoofed animals feature paired lower limb segments.
Evolutionary History
Over millions of years, mammals walking on the soles of their feet evolved to lift their heels off the ground, eventually walking entirely on their toes. This transition elongated the intermediate foot bones, turning them into extra stride-lengthening segments.
Photography Tips
Place the bone flat against a neutral background in natural daylight. Take one shot showing the entire length from the top to the bottom tips, and a close-up view of the joint areas to capture details.