How did jaws evolve?
Expansion of a pharyngeal arch, with loss of the 2-3 arches in front
Arch just behind the jaws includes a support brace for the jaws, the hyomandibula.
Upper jaw may fuse to chondrocranium (autostylic suspension) or may be independently mobile, anchored by a couple of ligaments (amphistylic suspension).
Odontodes incorporated into jaw as teeth.