Tarsometatarsus
Long bone, part of the appendicular skeleton
Also known as: Bird Lower Leg Bone or Drumstick Bone
Classification
Long bone, part of the appendicular skeleton
Dimensions
Varies widely from tiny songbird splinters just under an inch long to robust stretches of eight inches or more in larger wading birds like herons.
Key Features
Look for a long, slender, almost pin-like shaft that flares into a wider top end featuring tiny natural holes and channels, tapering down to a pulley-shaped bottom end where the toe bones once attached.
Similar Bones
Can be mistaken for a mammal's fibula or a slender rib fragment, but the distinct pulley-shaped bottom end and the flattened, perforated top plate give away its avian identity immediately.
Across Species
In the avian world, the tarsometatarsus is a clever fusion of several ankle and foot bones into a single, sturdy shaft, acting as an extra landing gear spring. Mammals keep these foot bones separate and separate the heel entirely from the ground, but birds walk on their toes with this long rod elevated, giving their legs that characteristic backward-bending look at the middle joint.
Evolutionary History
Over millions of years as dinosaurs evolved into birds, the individual foot bones of ancestors fused together to save weight and add incredible springing power for flight takeoffs and landings, turning the foot into a specialized shock absorber.
Photography Tips
Place the bone flat against a neutral, high-contrast surface with bright, even side-lighting to catch the subtle textures of the shaft. Include a small coin or ruler next to it for scale, and take one shot of the top end face-down and another showing the entire length from the side.