Hip Bone
Irregular bone, part of the appendicular skeleton
Also known as: Hip Bone or Pelvic Bone
Classification
Irregular bone, part of the appendicular skeleton
Dimensions
Large, flared, and asymmetrical shape with varied thickness, measuring about 20 centimeters across in typical adult humans.
Key Features
The most defining features are a deep, cup-shaped socket on the outer side for the leg joint, a broad, fan-shaped blade at the top, and a large opening near the bottom.
Similar Bones
Can be confused with the shoulder blade due to the flat, fan-like shape, but can be distinguished by the deep socket joint and the large inner openings rather than a flat spine ridge.
Across Species
In mammals, the hip bone provides the crucial anchor point for the hind limbs. Birds have an elongated, fused version that runs down much of their back to handle the stresses of landing and bipedal hopping, while whales have lost these limb-supporting pelvic structures entirely, retaining only tiny, floating remnants.
Evolutionary History
Tracing back to early tetrapods, the hip structure evolved to transition animals from sprawling bellies onto upright limbs, shifting from a simple brace into a complex basin that supports organs and transmits body weight during walking.
Photography Tips
Take photos against a neutral background with soft, even lighting to highlight the deep socket and curves. Include a coin or ruler for scale, and capture both the inner surface and outer socket view.