SAURO PTERYGIA 



85 



mosasaurs, indicating a greater flexibility than the ichthyosaurs 

 possessed. The ichthyosaur paddles must have been quite like 

 the fins of fishes in function, while doubtless those of the plesiosaurs 

 were capable of a more varied use, as indeed was required of them. 

 Their articulation with the trunk was more of a ball-and-socket 



Wk~\ 



tfir 



Fig. 38. — Paddles of Plesiosaurs: A, right hind paddle of Thaumatosaurus, after 

 Fraas; B, right hind paddle of Trinacromerum; C, right front paddle of same indi- 

 vidual; /, femur; fb, fibula; t, tibia; h, humerus; r, radius; it, ulna. 



joint than in the other reptiles, showing possibility of considerable 

 rotation on the long axis, and an antero-posterior propelling action. 

 The paddles were certainly more powerful than those of any other 

 aquatic air-breathing animals. There were no additional digits, 

 all plesiosaurs having neither more nor less than five in each hand 

 and foot. Hyperphalangy was sometimes carried to an excessive 



