The Skull of the Theromorpha
(Figs. 10 a–d, 11 a–d, 16 a–c, 32–42)
More modifications of the skull structure are found in this order than in the Cotylosauria, as would be expected. The interparietals and tabulars are probably sometimes absent, and they are always confined to the occipital surface when present, the former usually, if not always, unpaired. The supratemporals are doubtfully present in any. The quadratojugal is smaller and never extends far forward.
Fig. 32 bis. Theromorph skull: Ophiacodon mirus Marsh, lateral view. pa, parietal; po, postorbital; pf, prefrontal; l, lacrimal; j, jugal; qj, quadratojugal; q, quadrate.
The lacrimals seldom extend to the nares. The teeth are often wanting on the prevomers and are sometimes present on the coronoids. There is a lower temporal opening, bounded by the jugal, postorbital, and squamosal. In the Edaphosauridae only may it possibly extend to the parietal. The teeth of jaws and mandibles are more variable, often markedly anisodont, conical, obtuse, or compressed and sectorial.
