The Skull of the Phytosauria
(Figs. 65, 66, 67)
The skull of the Phytosauria is nearly uniform in general structure, characterized especially by the elongated face and posterior location of the external nostrils. No bones are fused in the midline, and none, save the primitive dermosupraoccipital, tabulars, and supratemporals are missing. The paroccipitals, as usual, are firmly fused with the exoccipitals. There is no parietal foramen. The supratemporal openings are more or less depressed below the level of the parietals but retain their primitive boundaries. The well-developed quadratojugals enter into the formation of the lateral temporal openings posteriorly. There is a primitive quadrate foramen between the quadratojugal and the quadrate. The stapes is slender. There is a large antorbital foramen bounded by the maxilla, nasal, lacrimal, and jugal.
The greatly elongated face is composed chiefly of the premaxillae, which extend back to the anterior ends of the nares, with the septomaxillae intervening, in the middle. The nostrils are surrounded by the large nasals and are elevated to or above the superior plane of the skull.
The bones of the palate retain their primitive relations, and there are small posterior palatine vacuities, larger in the more primitive forms. The pterygoids meet broadly in the median line, forming the roof of a deep respiratory channel between the heavy, underarching palatines, in some almost forming an incipient secondary palate, in the phytosaurs, as in the crocodiles, doubtless caused by the large flat tongue. The interpterygoidal opening and parasphenoid are small.
The elongate prearticular of the mandible is fused with the articular. As usual in slender-jawed reptiles with a long symphysis, the splenial participates in it, an acquired character. The condition of the coronoid is not yet definitely determined, but it is doubtless present, though small. A large foramen, so generally characteristic of the Archosauria, is constant in the outer wall of the mandible between the surangular, angular, and dentary.
The teeth are numerous, set in deep sockets and confined, as in other archosaurians, to the premaxillae, maxillae, and dentaries,
