210 



REPTILIA 



CLASS III 



situated external mires, large antorbital vacuities, form of the pterygoids and 

 basisphenoid, and the upwardly directed transverse processes of the anterior 

 dorsal vertebrae. With the Khynchocephalians they agree in having an in- 

 dependent postorbital, paired parietals and frontals, an extensive bony palate, 

 internal nares occupying their primitive position on either side of the vomers, 

 well-developed abdominal ribs, and a similar clavicle and coracoid. The 

 remaining bones of the pectoral arch, as well as those of the pelvic girdle and 

 appendicular skeleton, are intermediate in form between the corresponding 

 parts of modern Crocodiles and Rhynchocephalians. 



The Parasuchia are accordingly to be regarded as a collective type of reptiles, 

 from which the crocodilian stem early diverged and entered upon an indepen- 

 dent course of evolution. Parasuchian remains are more or less fragmentary, 

 and limited to the Trias of Europe, Asia, and North America. 



Belodon, v. Meyer (Phytosaurus, Jaeger), (Figs. 309, 310). This is the only 

 accurately known genus, and is represented by excellently preserved skulls, 



with portions of the skeleton and 

 dermal armour, in the Upper 

 Keuper of Stuttgart. It is about 

 as large as modern crocodiles, the 

 skull attaining a length of 0*7 m. 

 External cranial bones pitted and 

 rugose ; lateral eustachian passages 

 occupying open grooves on the 

 basisphenoid ; secondary palate 

 not developed. Dorsal armour 

 consisting of two longitudinal rows 

 of large, overlapping keeled scutes 

 vith coarse ornamentation ; sides and abdomen covered with smaller, more 

 irregular scutes. Detached teeth not uncommon in the Keuper of Wiirteni- 

 berg and Franconia. Fragmentary 

 remains also known from the Trias 

 of North Carolina, Pennsylvania, M HP 

 Connecticut, New Mexico, Arizona, 

 and Utah. 



Stagonolepis, Agassiz. Similar to 

 I'x'lniloit, but teeth with tumid base. 

 Ventral armour consisting of from 

 ti\e to eight rows of rectangular n . , 



t,,* 3 . ™ . 'cudii^iuai Psephoderma alpina, v. Meyer. Upper Trias ; Ruh, 



SCUteS. Elgin Irias. Polding, Bavaria. Ventral armour, i/ 4 (after H. v. 



Parasuchus, Huxley; Episcopo- eyer) ' 



Cope. These are imperfectly known genera, the former from the 

 Gondwana Formation of Maleri, India, and the latter from the New Mexican 

 Trias. 



t Psephoderma, v. Meyer (Fig. 311). Known by fragments of dermal 

 armour from the Alpine Upper Trias, and formerly referred to Chelonians 

 < Dermochelydidae). 



Fig. 310. 



Belodon kapffi, v. Meyer. Upper Keuper ; Wiirtemberg. 

 Dorsal scute, 1/3 (after H. v. Meyer). 





