138 



THE PERMO-CARBONIFEROUS RED BEDS OF 



possibly the remains of dermal scutes, but no abdominal ribs have been 

 detected, and he is certain that there were none. The movements were slow 

 and sluggish, probably similar to those of a land salamander. The "long 

 and slender teeth were utterly useless for the seizure and retention of large 

 prey. I think it very probable indeed that its food consisted in a large part, 

 probably wholly, of the smaller invertebrates, cockroaches, land molluscs, 

 worms, etc." (Williston.) 



Seeking protection and food in the deep vegetation, Seymouria was sub- 

 ject to attack from carnivorous forms, which would, as suggested for other 

 forms, grasp at it from above. This is, perhaps, the reason for the great 

 development of the neural arches, which, as WiUiston remarks, "form almost 

 a carapacial protection for the body." 



Pantylosauria. 



Pantylus. — Nothing can be said of the form or size of this creature. The 

 skull alone is known, but served to show the presence in the fauna of a 

 typical, durophagous (conchifragous) animal. 



Pelycosauria. 



Varanosaurus and Varanoops (fig. 24). — This is the best known of a 

 group of long, slender, probably semi-aquatic, lizard-like reptiles, with many 

 points in their structure which ally them with the Proterosauridce. The sktiU 



Fig. 24. — Restoration of Varanoops brevirostris Williston. About one-seventh natural size. 



was more or less elongate, with sharp, conical, nearly isodont teeth. The 

 limbs and feet were well formed and fairly long, the carpus and tarsus well 

 ossified, the tail long and slender. They were probably able to move almost 

 equally well on land or in the water, and there is a suggestion of agility which 

 permits us to imagine them slipping with great speed through the under- 

 brush, as they sought their prey, or escaped from larger forms. With equal 

 ease and speed they may have glided into the pools or rivers, pursued or 

 pursuing, and flashed through the water as would a modern Varanus. Paleo- 

 hatteria, the nearest ally among the Proterosauria, was far more clumsy in 

 its build, with much more cartilage in its joints and with weak feet. 



Varanosaurus reached a length of a meter or more, and Pcecilospondylus 

 was about the same size. Theropleura and Poliosaurus reached a greater 

 length, perhaps as much as 2 meters. 



In New Mexico there were very similar, but generally distinguishable, 

 forms — Ophiacodon, Elcabrosaurus, and the creature originally described as 



