Neurocranium (specifically the occipital and sphenoid region of a teleost fish skull)
Irregular bone, part of the axial skeleton
Also known as: Fish skull roof and braincase
Classification
Irregular bone, part of the axial skeleton
Dimensions
Varies widely depending on the fish species, typically ranging from a fraction of an inch in small minnows to several inches across in larger predatory fish like cod, salmon, or bass.
Key Features
Look for symmetrical wings, hollow chambers that once held the brain or inner ear organs, delicate spider-web-like struts of bone, and an overall butterfly or spaceship-like silhouette when viewed from the top or bottom.
Similar Bones
Bird sternums or small mammal pelvis fragments. You can tell fish neurocrania apart by their intricate, lightweight lattice structure, hollow inner chambers, and lack of the heavy density found in mammalian limb or hip bones.
Across Species
Unlike the solid, fused skull bones of mammals, fish skulls are made up of many delicate, individual plates that fit together like a 3D puzzle. This specific piece forms the intricate inner chamber that houses the brain and supports the gills and jaw structures in bony fish.
Evolutionary History
The complex array of bones forming the fish braincase has ancient roots dating back to the earliest armored jawless and jawed fish of the Paleozoic Era. Over hundreds of millions of years, these numerous dermal and cartilage-replacement bones streamlined and fused in some lineages while remaining separate and lightweight in modern bony fish.
Photography Tips
Place the bone on a solid, neutral-colored background. Take photos from the top, bottom, and side angles to capture the hollow chambers and intricate bony struts. Include a coin or ruler next to the bone for scale.