Cranium plate
Flat bone, part of the core axial skeleton
Also known as: Skull fragment, head plate
Classification
Flat bone, part of the core axial skeleton
Dimensions
Varies widely by species and individual, typically presenting as thin to moderately thick curved plates with a sandwich-like cross section of dense outer layers enclosing a spongy middle layer.
Key Features
Smooth or slightly textured outer surfaces, a gently curved profile matching the rounded shape of a head, and a distinctive sandwich structure visible on the edges where hard outer layers enclose a porous inner core.
Similar Bones
Can be confused with large flat body plates from turtles or fragments of shoulder blades. Skull plates are usually distinguished by their gentle natural curvature and the sandwich-like internal texture.
Across Species
In mammals, these skull roof plates fit together like puzzle pieces with zigzag edges called sutures. Birds feature highly fused plates that become a single lightweight shell, while reptiles often retain separate, textured plates that can display intricate surface ornamentation.
Evolutionary History
These protective head bones trace their origins back to ancient armored fish of the Paleozoic era, evolving from dermal armor plates in the skin into the sophisticated enclosing braincases seen in modern land-dwelling vertebrates.
Photography Tips
Photograph these pieces flat against a neutral background with strong side lighting to highlight subtle surface textures and edge thickness. Include a small ruler or coin for scale.