Frontal bone
Flat bone of the core axial skeleton
Also known as: Forehead bone
Classification
Flat bone of the core axial skeleton
Dimensions
A broad, curved plate forming the front upper portion of the skull, measuring roughly six to seven inches across in humans.
Key Features
Look for a smooth, curved upper shield featuring two prominent brow ridges along the bottom edge and gentle curves that sweep back over the top of the head.
Similar Bones
Can be confused with other curved skull cap plates like the parietal bones, but the forehead bone is easily distinguished by its distinct brow arches and sweeping lower shelf that forms the roof of the eye sockets.
Across Species
In many mammals, the forehead region is heavily reinforced or modified into horns, antlers, or flat battering surfaces, whereas in primates it remains smooth and expansive to shelter a growing brain.
Evolutionary History
Evolving from the dermal armor plates of ancient fish ancestors, this bone shifted inward over hundreds of millions of years to encase and protect the expanding forward chambers of the vertebrate brain.
Photography Tips
Photograph straight-on from the front to capture the symmetry and brow arches, and take a second side-profile shot to show the smooth curve of the top surface. Use soft lighting to highlight the natural contours and include a coin or ruler for scale.