Articulation between the pectoral fin base and the pectoral girdle in the megamouth shark.

(A) Pectoral girdle: lateral view of the right pectoral girdle (left), and close-up view of the articulation surface for the pectoral fin (right). (B) Close-up view of the articulation between the pectoral girdle and the pectoral fin. The pectoral fin base twists approximately 90°. co, coracoid; ms, mesopterygium; mt, metapterygium; pt, protopterygium.