Dermatocranium

The dermatocranium is the portion of the vertebrateskull that is composed of dermal bone, as opposed to the chondrocranium and splanchnocranium, which are composed of endochondral bone. Bones of the dermatocranium originate from integumentary bony armour in the earliest fishes, only later fusing to the endochondral skull bones.

The dermatocranium comprises the skull roof, the facial skeleton, and—in fishes—the opercular bones. During the early evolution of tetrapods, a number of the bones in the posterior skull separated to become the dermal portions of the shoulder girdle.