ADAPTIVE RADIATION OF REPTILES 



197 



graphic condition most favorable to the preservation of Hfe 

 in the fossil condition is that known as the flood-plain, in which 

 the rising waters and sediments of the rainy season rapidly 

 entomb animal remains which are deposited on the surface 



Fig. 74. Close of the Age of Reptiles. A Relic of Ancient Flood-plain Condi- 

 tions. 



Iguanodont dinosaur lying upon its back. Integument impressions preserved. The 

 "dinosaur mummy," Trachodon, from the Upper Cretaceous flood-plain deposits of 

 Converse County, Wyoming. Due to arid seasonal desiccation, the skin folds and 

 impressions are preserved over the greater part of the body and limbs. Discovered 

 by Sternberg. Mounted specimen in the American Museum of Natural History. 



or in small water pools during the drier seasons. Fossils 

 buried in old flood-plain areas of South Africa tell us the story 

 of the life evolution which is continued by the ancient shore 

 and lagoon deposits in other parts of the world as well as by 

 fossils found in the broad, intermittent flood-plain areas of 

 the American Triassic and Cretaceous, which close with the 



