Humerus (Upper End)
Long Bone, part of the appendicular skeleton (the limbs).
Also known as: Upper Arm Bone or Wing Bone fragment
Classification
Long Bone, part of the appendicular skeleton (the limbs).
Dimensions
The humerus is typically a sturdy, cylindrical bone. This upper portion is characterized by a rounded, ball-like surface that is usually wider than the main shaft of the bone.
Key Features
Look for the 'head' of the bone, which is a smooth, rounded dome shaped like a mushroom cap or half-sphere. Below this dome, there are usually small, rugged bumps where muscles once attached, and the bone begins to narrow into a straight, hollow tube.
Similar Bones
This can be confused with the upper end of the femur (thigh bone). To tell them apart, look at the 'neck'; the femur usually has a very distinct, long neck that keeps the rounded ball far away from the main shaft, whereas the humerus head sits more directly on top of the bone.
Across Species
In the natural world, the humerus varies wildly: in moles, it is short and blocky for powerful digging; in birds, it is often hollow and light to assist with flight; and in swimming mammals like whales, it is flattened into a paddle shape. This specimen shows the characteristic rounded dome that allows for a wide range of circular motion, common in mammals and birds alike.
Evolutionary History
Tracing back to the first lobe-finned fish that crawled onto land, the humerus has always been the single, stout bone that connects the shoulder to the rest of the limb. Over millions of years, it has shifted from a flat, robust plate in early amphibians to the more elongated, versatile rod seen in modern land-dwelling vertebrates.
Photography Tips
To get the best identification, place the bone on a flat, neutral surface and take a photo from directly above. Include a common object like a coin or a ruler for scale, and take a second shot from the side to show the profile of the rounded top.