EXTINCT REPTILES. 623 



Pythonomorpha. These strange Cretaceous Reptiles should pro- 

 bably be placed near the Lacertilia and the Rhynchocephalia. They 

 are specially characterised by the enormous elongation of the body, 

 which sometimes reached a length of 75 to So ft. The skull is like 

 that cf the Monitor among the lizards, but, according to Cope, it also 

 presents affinities with snakes. The body is snake-like, but there are 

 two well-developed pairs of limbs, forming swimming-paddles. All 

 were carnivorous and marine ; the distribution was cosmopolitan. 

 Examples. Mosasaiirns, Clidastes, Liodon, Dolichosaiirus. 



Dinosanria. Terrestrial Reptiles, ranging from the Trias to the 

 Chalk, often very large, and, like Marsupials, specialised in various 

 directions. They were long-necked and long-tailed forms, some bipedal, 

 some quadrupedal. The skull has a superior and inferior temporal 

 arcade, a fixed quadrate, teeth in sockets, and confined to the margins 

 of the jaws. They exhibit many points of resemblance to Crocodiles 

 and Rhynchocephalia on the one side and to Birds on the other. The 



FIG. 307. Comparison of pelvic girdles of cassowary 

 (to left) ; Iguanodon, an extinct Reptile (in centre) ; 

 crocodile (to right). 



//., Ilium ; Is., ischium ; P., pubis (epipubis in crocodile). 



pelvis and hind-limbs are particularly avian, e.g. in the tendency to 

 form a tibio-tarsus. Brontosannis, a gigantic, herbivorous form, nearly 

 60 ft. in length, was probably amphibious. Atlantosaunis was even 

 larger, the femur measuring over 6 ft. in length. Compsognathus, 

 Igitanodon, and Cainptosaiints are examples of the "bird-footed" 

 herbivorous Dinosaurs. Compsognathus only reached a length of 2 ft., 

 and hopped on its hind-legs like a bird. Iguanodon habitually walked 

 on its hind-limbs, and, like several others, had hollow bones ; it reached 

 a height of 15 ft. Of the carnivorous Dinosaurs, Megalosattrus is a 

 good type. The pelvis has a Crocodilian aspect, for the pubes slope 

 forwards instead of backwards, as in Birds and Iguanodon, etc. The 

 limbs were furnished with powerful claws, and the teeth show much 

 specialisation. 



Pterosanria or Pterodactyls. Flying Reptiles, represented from the 

 lower Jurassic to the Upper Chalk, exhibiting many points of resem- 

 blance to Carinate Birds, but still distinctly Reptilian in type. They 

 resemble birds especially in some features of the skull and pectoral 



