650 



GEOLOGY. 



refers to the mammalian features, the former to the peculiar denti- 

 tion. The theromorphs deployed into four suborders, and became 

 the dominant group among the earliest reptiles in each quarter of 

 the globe where they have been discovered. 1 The most primitive 

 of the suborders was ihe Pareiasauria or Cotylosauria, by many paleon- 

 tologists now considered of ordinal rank, whose type family included 

 the pioneer genus above illustrated. This family was abundantly 

 represented in South Africa and in several parts of Europe, notably 



Fig. 302. — Pareiasaurus serridens, of Cape Colony, S. Africa, Karoo formation; 



X about Js- (After Broom.) 



northern Russia, where Amalitzky has recently found many skeletons. 2 

 This family is not known in America, but two other pareiasaurian 

 families are represented by several genera (Otocoelus, Pariotichus, 

 Isodectes, Pantylus, Hypopnous, Empedias, Diadectes, Chilonyx, Bol- 

 boden). This distribution is very notable, considering the early stage 

 of evolution of the reptiles. 



The reptiles grouped under the suborder Theriodontia possess 

 peculiar interest because of the mammalian aspect of their skulls, of their 

 dentition, and of many features of their skeletons (Fig. 303). They 

 were especially abundant in South Africa (Karoo beds 3 ), but they 

 have been found also in Bohemia, and notably in Russia (Amalitzky). 



1 A. S. Woodward, Vert. Pal., p. 144. 



2 Compt. Rend., March, 1901. 



3 It is well to bear in mind that the Karoo beds, so wonderfully rich in significant 

 vertebrate remains, are regarded as Permian in part and Triassic in part, and that 

 a portion of their theromorphs belong to the latter. See also Broom, Geol. of Cape 

 Colony, 1905, pp. 228-249. 



