NORTH AMERICA AND THEIR VERTEBRATE FAUNA. lOI 



The weight of evidence is still very strongly in favor of the belief that amphib- 

 ians were as severely restricted to fresh water in the past as at present. 



An abundance of amphibian remains shows almost conclusively that the 

 beds in which they occtir were deposited in freshwater, or so near to a land with 

 bodies of fresh water that the remains could be easily swept out and deposited 

 with the material of the beds after death. The occurrence of such moUusciv- 

 orous animals as Diadectes, Edaphosaurus, and Pantylus suggests the proxim- 

 ity of a shoreline with an abundant food-supply, but this need not have been 

 the edge of a salt-water sea, as there were in all probability numerous fresh- 

 water and even land molluscs which could have supported these animals. 



No reptiles have as yet been discovered which show a great advance in special- 

 ization toward an aquatic life. 



The majority of forms are such as would lurk in secure places in the waters 

 of lakes, swamps, or streams, or hide in the vegetation which lined their banks. 

 Undoubtedly many of them swam freely at times, but none ever approached 

 the high degree of aquatic specialization exhibited in the Plesiosaurs, Icthyo- 

 saurs, or Mosasaurs. Some ranged more freely in the open, or in thick wood- 

 lands and underbrush, or like Casea, perhaps, may have lived in bare and 

 arid places, or have been like Areoscelis, at home in the branches of the tree- 

 like vegetation. 



The fauna was one of estuaries, swamps, lagoons, alluvial plains, and 

 open or covered woodlands. There is no evidence of even semipelagic forms 

 unless it be the genus Cricotus and possibly Chenoprosopus; and no certain 

 evidence of any forms which inhabited a marine riparian. 



FOOD HABITS AS INDICATED BY THE TEETH. 



The fishes, so far as can be learned from the form of the teeth, were very 

 similar in habits to living forms in the same groups. 



The amphibians show the universal carnivorous dentition ; the teeth in all 

 are simple, conical, grasping organs with slight power of mastication. 



In some, as Eryops, Cacops, Trematops, etc., there were large tusks on the 

 vomers, palatines, and maxillaries, which served as accessory grasping organs, 

 indicating the habit of seizing more or less powerful and active prey. In 

 other forms the teeth form a single, uniform series in both the upper and lower 

 jaws. The larger forms were undoubtedly voracious feeders, and carried 

 destruction into the ranks of the smaller and more helpless creatures. The 

 bones of fishes, smaller amphibians and reptiles are abundant in the copro- 

 lites, a considerable proportion of which must be from the larger Amphibia. 



The feeble dentition of Lysorophus, Diplocaulus, Cardiocephalus, etc. , shows 

 that they were confined to a diet of smaller and soft-bodied animals, worms, 

 insect larvae, and unprotected crustaceans and molluscs, with such dead bodies 

 as might be discovered, and, perhaps, even some forms of vegetation. 



Among the reptiles a greater variety of food habits is indicated by the 

 character of the teeth, but so far no form has been discovered which can be 



