sentences:  Some species, such as Tarsiers, have a postorbital septum.This septum can be considered as joined processes with a small articulation between the frontal bone, the zygomatic bone and the alisphenoid bone and is therefore different from the postorbital bar, while it forms a composite structure together with the postorbital bar.Other species such as dermopterans have postorbital processes, which is a more primitive incomplete stage of the postorbital bar.