CROCODILIA 



211 



jaw, but the thalattosuchians did not. The teeth were about as 

 numerous as in the modern gavials, but they projected freely only 

 a short distance above the gums in life, and they were very slender 

 and sharply pointed, excellently well adapted for catching smooth 

 and slippery fishes. Their vertebrae, like those of all other reptiles 

 of their time, were biconcave. Those of the neck resembled those 

 of the teleosaurs, save that there were only seven, fewer than is the 

 case with any other members of the order. In becoming adapted 

 to their peculiar mode of life these crocodiles lost two vertebrae 

 from the neck. All modern crocodiles have two ribs attached to the 

 first vertebra; the thalattosaurs had but one, another evidence of 



Fig. 109. — Tail, scapula (sc), and coracoid (c) of Geosaurus. (After Fraas) 



primitive characters. While the number of vertebrae in the neck 

 was reduced, in the back it was increased to eighteen; all other 

 crocodiles have but fifteen or sixteen. The trunk was long, another 

 adaptation to water life. There were two firmly united vertebrae 

 in the sacrum, as in the modern forms. The reason for the per- 

 sistence of this terrestrial character we shall see later. 



The tail was very long and strong, nearly as long as all the 

 remainder of the body, and relatively much longer than in other 

 crocodiles. It is of interest to observe that the head, neck, body, 

 and tail had almost the same relative proportions as those of the 

 great sea-lizards, the mosasaurs. The terminal bones of the tail 



