Frontal Bone
Flat bone; Axial skeleton
Also known as: Forehead bone
Classification
Flat bone; Axial skeleton
Dimensions
In mammals, this bone typically forms a broad, curved plate. In humans, it is roughly bowl-shaped, while in many four-legged animals, it is longer and flatter, matching the shape of the snout.
Key Features
Look for the distinct rounded forehead area and the thickened ridges that sit above the eye sockets. In many species, you will notice a small notch or hole above the eye and a jagged, puzzle-piece-like edge where it meets other skull bones.
Similar Bones
The parietal bones (which sit further back on the head) are often confused with the frontal bone. You can tell them apart because the frontal bone always includes the top border of the eye sockets, whereas the parietal bones are simpler plates with no eye-related features.
Across Species
The frontal bone varies wildly across the animal kingdom. In many horned animals like bulls or goats, the frontal bone serves as the thickened base for horns. In birds, it is extremely thin and light to save weight for flight, while in elephants, it contains large air pockets to keep the skull light despite its massive size.
Evolutionary History
Tracing back to ancient fish, the frontal bones were originally part of a series of protective armored plates. Over millions of years, these plates moved and fused to encapsulate and protect the growing brains of land-dwelling vertebrates, eventually forming the sturdy roof of the modern skull.
Photography Tips
Take photos from directly in front and from a side profile. Place a ruler or a coin next to the bone for size reference, and try to use soft, natural light to highlight the subtle texture of the forehead and the curves of the eye ridges.