158 



WATER REPTILES OF THE PAST AND PRESENT 



pliability and flexibility of the lingers and toes were certainly very 

 great, but they could not possibly have been flexed or bent so 

 as to grasp or seize anything; aiid of course all vestiges of claws 

 had disappeared. Many specimens have been found with all the 

 bones of the limbs, that is, the "paddle bones," in the positions thev 



occupied when the animals 

 died. Figures of three such 

 specimens, made from photo- 

 graphs or careful drawings by 

 the writer, are shown here- 

 with (Figs. 74-76) . In several 

 such specimens very clear 

 impressions of the smooth 

 membranes between the 

 fingers have been observed, 

 and in one specimen pre- 

 served in the collections of 

 the University of Kansas the 

 outline of the fleshy parts 

 connecting the paddle with 

 the body has been preserved. 

 It will be seen by com- 

 parison of the figures of the 

 mosasaur paddles with those 

 of the ichthyosaurs and ple- 

 siosaurs that there was a wide 

 difference in their structure, 

 though all have the charac- 

 teristic shortening of the limb 

 bones and increase In the 

 numbers of the finger and 

 toebones, that is hyperphalangy. It is probable that these differ- 

 ences mean a more powerful and varied use of the limbs in the 

 mosasaurs. It is certain that the mosasaurs were much more pre- 

 daceous and pugnacious in their habits than were any other truly 

 aquatic back])oned air-breathing animals of the past or present. 

 They were the ''land sharks" of the ancient seas, and probably 



Fig. 76. — Platecarpus; right, front paddle: 

 /;, humerus; r, radius; u, ulna. 



