THEROMORPHA (Neo-Lat. now. pl., from Gk. Oip, tiler, wild beast + aopcp), morphe, form). A name applied to several widely dissimi lar groups of fossil reptiles which possess certain common characters of skull, vertebra, limb girdles, and digital formula. Another ordinal name, Ationtodantia, is often used synonymously with Theromorpha. The theromorphs, together with the turtles and plesiosaurs, compose the great rep tilian division Nynapsida (Osborn), characterized by certain mammal-like features of the skull and the mammalian digital formula. All known theromorph remains have been found in the rocks of Permian and Triassic age. They were for the most part animals of rather heavy build, adapted to land life and sluggish habit, though one group appears to have been marine. The following sub orders are commonly recognized: (I) Cotylosauria or Pareiasauria. A group of reptiles having a solid cranial roof with a large pineal foramen, and usually with teeth on the venter, pterygoid, and palatine bones. It is prob able that these forms stand closest to the ances tral Stegocephalia or armored Amphibia. The best-known example is Pareiasaurus, from the Karoo beds of South Africa, a heavily built land animal, eight feet long. (2) Theriodontia. A
group which closely resembles mammals in the differentiation of the teeth into incisors, canines, and molars, and in certain features of the skull. Most genera have a distinctly car nivorous dentition, but a few, the Gompho dontia, have crushing molars. Nearly all the known theriodonts are from the South African Trias. Cynognathus, in which the skull is re markably dog-like, equaled the black bear in size and general proportions. 'Many zoologists be lieve that mammals have been derived from theriodonts. (3) Dieynodontia. Land reptiles from the Tries of Scotland and South Africa, known chiefly from the skull, which is greatly modified, having the teeth entirely wanting, as in Udenodon, or reduced to a single pair of large tusks in the upper jaw, as in Dieynodon and Gor donia. (4) Placodontia. Named from the large, knob-like crushing teeth. Plaeodus, the first named genus from the marine Trias of Germany, was long known only from these teeth. The genus Placochelys is known to have had a carapace com posed of a mosaic of small plates. The view held by some paleontologists that placodonts are ancestral to turtles is untenable.