THE AGE OF REPTILES 



53 



The deposits of Texas, extending northward through Oklahoma 

 to the south line of Kansas, are of considerable extent, for the most 

 part lying along the Wichita River and its tributaries, north of 

 Seymour, Texas. They are composed chiefly of red clays and 

 sandstones of fresh-water or delta origin, perhaps eight hundred 

 feet in total thickness. Beds of like character and yielding similar 

 fossils are also known from northern New Mexico on the tributaries 

 of the Chama River. Their chief characters, as well as restorations 

 of some of the more noteworthy forms, have already been given. 



No vertebrate fossils are known in America from the Upper 

 Permian and Lower Triassic. Marine limestones of Middle and 



Fig. 29. — Restoration of Varanops, a. theromorph reptile from the Permian of 

 Texas; about four feet long. 



Upper Triassic age of Nevada and northern California have yielded 

 numerous remains of primitive ichthyosaurs, the only known re- 

 mains of the thalattosaurs, and a few others of doubtful affinities, 

 all of which have been described by Dr. Merriam. The Upper 

 Triassic exposures, of considerable extent, occur between the Pitt 

 River and Squaw Creek in Shasta County, CaHfornia. ReptiUan 

 remains from the Middle Triassic are so far known only from the 

 limestones of West Humboldt and New Pass regions of western and 

 central Nevada. 



Land reptiles of Middle and Upper Triassic age are known from 

 many widely separated locahties in the United States, but chiefly 

 from the extensive "red beds" of the Rocky Mountain region 



