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The skull of the typical Pseudosuchia is very much like that of the Pelycosimia (Fig. 64), in structure. All the bones of the skull roof are present except the dermosupraoccipital, tabular, and supratemporal; the lacrimal is small; there is no parietal foramen; and the palate bones have the primitive relations. Other forms, however, referred to this group provisionally, have both the dermosupraoccipital and tabular (Youngina, Fig. 64 ), and teeth on the prevomers and pterygoids (Proterosuchus). The upper and lateral temporal openings, a large antorbital vacuity and one in the mandible, are like those of the Parasuchia. The antorbital foramen is large, as are also the orbits. The supratemporal foramen is large and never posterior in position.

The skull of the Pelycosimia differs from that of the Phytosauria chiefly in the position of the external and internal nostrils near the extremity of the face, and at a considerable distance in front both of the orbits and antorbital openings. The face is short in front of the nostrils. There is also no respiratory channel back of the internal nostrils, so characteristic of the phytosaurs. The skull is markedly carnivorous in type.