ORDER I 



RHYXCHOCEPHALIA 



147 



Sub-Order 1. PROTEROSAUEIA. Seeley. (Proganosauria, Baur.) 



Abdominal ribs small, arranged in several longitudinal series. Pubis and ischium 

 imperfectly fused. Fifth metatarsal not dissimilar from the rest. Marginal teeth in 

 a single uniform series. 



The sub-order is of interest as comprising some of the most primitive and 

 most ancient reptiles known to science. They are regarded by many authors 

 as ancestral not only to the Sphenodon group, but to all Archosauria, or reptiles 

 with two cranial arches. There is much reason to suppose that from these 

 forms also a Dinosaur-avian stem was evolved in the Permian, from which 

 birds have come down to us. 



Family 1. Proterosauridae. 



Maxillae, premaxillae, and mandibles with a series of large conical teeth, either 

 acrodont or implanted in shallow alveoli, and smaller teeth present on the palatines 

 and vomer. Interclavicle elongate, with a rhombic expansion at its anterior end. 

 Permian and Trias. 



Palaeohatteria, Credner (Fig. 238). Body lizard-like, about 25 cm. long. 

 Vertebral centra in the form of delicate constricted amphicoelous cylinders, 



lin.l 



M 





D 



E 



Fig. 238. 



Palaeohatteria longicaudata, Credner. Lower Permian: 

 Saxony. A, Skull, somewhat distorted, l /i- 5, Pectoral 

 arch. ' C, Pelvic arch. D, Dorsal vertebra; E. Caudal 

 vertebra, anterior aspect. (". Acetabulum; d, Clavicle ; 

 cor, Coracoid ; f, Femur; ft., Humerus ; ic, Intercentrum ; 

 interclavicle; il, Ilium; ju, Jugal; la, Lachrymal; 

 n, Pedicle of neural arch; na, Nasal; o, Obturator notch ; 

 pmx, Premaxilla; por, Postorbital ; prf, Prefrontal; pu, 

 Pubis; quj, Squamosal and quadrate; vo, Vomer (dis- 

 placed); :. Zyapophysis. Orbit overlaid by displaced 

 facial bones of the right side), (after Credner). 



with persistent notochord ; small intercentra occur between all in advance of 



