where the palatoquadrate is movable and detachable, a trait known as hyostyly. The back of the head is supported by a complex of fused vertebrae called the synarcual, which also connects to the dorsal fin spine.

Instead of sharks' many sharp, consistently-replaced teeth, chimaeras have just six large, permanent tooth-plates, which grow continuously throughout their entire life. These tooth-plates are arranged in three pairs, with one pair at the tip of the lower jaws and two pairs along the upper jaws.