Dragons of Sea and Aii' 



preyed upon their smaller relatives. With such 

 fishes as Xiphactinus present and numerous, it 

 seems as though the reign of the mosasaurs 

 could not have been entirely peaceful. 



Other dragons of the sea were the plesio- 

 saurs, great marine reptiles that dwelt in the in- 

 land sea with the mosasaurs and swam about our 

 eastern and southern coasts. For the most part 

 they were not the typical species so familiar 

 to us from books, with small heads and long 

 necks, but large-headed, short-necked animals, 

 although plesiosaurs in structure. Long-necked 

 forms were not, however, entirely absent, for 

 these were represented by species of the genus 

 Elasmosaurus, There is a parallel to this 

 among turtles, for the short-necked sea-turtle 

 and long -necked, soft -shelled species of our 

 Southern and Western States are both unmis- 

 takably turtles, although quite unlike in their 

 proportions and appearance. The plesiosaurs 

 are among the numerous examples we have of 

 the manner in which Nature attains the same 

 end by different means. With mosasaurs the 

 tail was the chief means of propulsion, and the 



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