Humerus fragment
Part of a long bone from the limb (appendicular) skeleton
Also known as: Upper arm bone (animal)
Classification
Part of a long bone from the limb (appendicular) skeleton
Dimensions
Typically longer than it is wide, with heavy, thick walls; most reach several inches in length depending on the mammal.
Key Features
Look for a cylindrical shape with a very thick outer layer of bone and a spongy, honeycombed interior. It often has a slight twist or specialized ridges where large muscles once attached.
Similar Bones
This can be confused with the femur (thigh bone) or tibia (shin bone). The upper arm bone usually has more complex, rounded knobs at the top and a distinct hourglass-shaped hinge at the bottom.
Across Species
In mammals like deer or bears, the upper arm bone is incredibly sturdy to support weight. In birds, it is often hollowed out to save weight for flight, while in marine mammals like seals, it becomes short and paddle-shaped to act like a flipper.
Evolutionary History
This bone can be traced back to the first lobe-finned fish that transitioned toward land. Over millions of years, it evolved from a fin support into a powerful lever that allows land animals to walk, climb, or dig.
Photography Tips
Place the object on a flat, neutral-colored surface next to a ruler or a coin for scale. Capture one shot showing the hollow or honeycombed end and another showing the full length of the outer surface.