The opisthotic lies between the epiotic and the lateral occipital with which it ultimately fuses; in some birds, e.g.
Here the opisthotic bone appears in the occipital region, as in the adult Chelonian.
Eo, Opisthotic. prp, Pterygoid process of sphe eu, Eustachian tube.
Op, Opisthotic. pa, Palatine.
Parietal bones separated by the supraoccipital; prootic and exoccipital separated by the enlarged opisthotic. Pectoral arch suspended from the skull; no mesocoracoid arch.