Phalanx
Long bone, part of the limb skeleton
Also known as: Toe bone or finger bone
Classification
Long bone, part of the limb skeleton
Dimensions
Small and slender, typically measuring between two and six centimeters in length depending on the animal species, featuring a narrow central shaft and wider ends.
Key Features
Characterized by a smooth, curved upper end shaped like a spool or pulley, a narrow pinched middle shaft, and a slightly flared, textured bottom end designed to connect with neighboring bones.
Similar Bones
Can be easily confused with metapodials or small fragments of larger limb bones, but can be distinguished by its distinct pulley-like joint surface at one end and diminutive, symmetrical proportions.
Across Species
In mammals, these bones form the digits of hands and paws, providing flexibility for walking and grasping. Birds have highly fused and modified versions within their wings and feet, while aquatic mammals like whales conceal stout, shortened versions within their flippers.
Evolutionary History
These repeating modular units evolved from the fin rays of ancient lobe-finned fish, gradually transforming over hundreds of millions of years into the weight-bearing and grasping digits of land-dwelling vertebrates.
Photography Tips
Place the bone flat against a neutral background alongside a ruler or coin for scale. Capture a top-down view with bright, even lighting to highlight the curved joints and the texture of the central shaft.