Polynesian mandibles.

Adult Polynesian mandibles are predominantly of the rocker form. Polynesian crania have an open cranial base angle, and a rather large upper facial height in the adult. The mandibular growth rotations necessary for normal occlusion to be maintained in the presence of this cranial morphology lead to development of a particularly small gonial angle. There is an increased 'bowing' of the basal component of the bone. Such 'bowing' leads to a sufficiently posterior displacement of the basal component in the gonial region for the development of a distinct angular process (for muscle attachment) to be unnecessary.