A GREAT PERMIAN DELTA 



565 



Fig. 10. Restoration of Naosaurus. 



The family of the high-spined Pelycosaurs did not monopolize the 

 wonders of the reptilian horde; however the borders of the streams,, 

 the swamps and the uplands, harbored other forms whose structure is 

 just beginning to be understood. One group of these, called by Cope 

 the Cotylosauria, is the most primitive of the reptiles and the nearest 

 to the amphibians. These animals were low-bodied and sprawling, with 

 a head completely roofed over by bone and showing between the orbits 

 the third, or pineal, eye. Rudiments of this third eye are still present 

 in the human brain, the pineal gland between the cerebrum and 

 cerebellum, and in many of the modern lizards it is still so far 

 functional as to have a rudimentary retina perhaps capable of perceiv- 

 ing light. 



Another group of reptiles closely resembling the Cotylosauria in 

 outward appearance, but differing in many details, notably the develop- 

 ment of a body armor, were placed by Cope in a separate order, the 

 Chelydosauria. As indicated by the name, the Chelydosauria are prob- 

 ably the ancestors of the turtles. Aside from more technical points 

 this relationship is shown by the development of a more or less com- 

 plete carapace. The skeleton of the larger forms is pretty well known 

 and the general shape is shown in the restoration of the skeleton of 

 Biadectes, Fig. 11. The teeth are elongated transversely and flattened, 

 telling of a purely vegetable diet; the dermal armor consisted of five 

 overlapping plates on each side lying on the first five dorsal ribs; the 

 anterior one is small, the second much larger and the last three smaller 

 again. In certain small forms, Otocceeus and Conodectes, the armor 

 was much more perfect, consisting of strong dermal plates correspond- 



