54 ANIMALS OF THE PAST 



is a sort of joint in each half of the lower jaw 

 which permits it to bow outward when opened, 

 and this, aided by the articulation of the jaw 

 with the cranium, adds greatly to the swallow- 

 ing capacity. Thus in nature the same end is 

 attained by very different methods. To bor- 

 row a suggestion from Professor Cope, if the 

 reader will extend his arms at full length, the 

 palms touching, and then bend his elbows out- 

 ward he will get a very good idea of the ac- 



Fig. 10. Jaw of a Mosasaur, Showing the Joint that 

 Increased the Swallowing Capacity of that Reptile. 



tion of a Mosasaur's jaw. The western sea 

 was a lively place in the day of the great 

 Mosasaurs, for with them swam the king of 

 turtles, Archelon, as Mr. Wieland has fitly 

 named him, a creature a dozen feet or more in 

 length, with a head a full yard long, while in 

 the shallows prowled great fishes with massive 

 jaws and teeth like spikes. 



There, too, was the great, toothed diver, 



