RULERS OF THE ANCIENT SEAS 39 



the length of his mandibles, this allowing so much 

 spring that when open they bow apart to form a nice 

 little landing net. In the Mosasaurs, as in the cormo- 

 rants, among birds, there is a sort of joint in each 'half 



Jaw of Mosasaur showing the joint that increased the 

 swallowing capacity of that reptile. 



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 swallowing capac- 

 ity. Thus in nature the same end is attained by very 

 different methods. To borrow a suggestion from Profes- 

 sor Cope, if the reader will extend his arms at full 

 length, the palms touching, and then bend his elbows 

 outward he will get a very good idea of the action 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 so 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. Hesperornis 

 (see page 58), while over the waters flew pterodactyls, 

 with a spread of wing of twenty feet, largest of all flying 

 creatures; and, not improbably nay, very probably 

 fish-eaters, too; and when each and all of these were 

 seeking their dinners, there were troublous times for 

 the small fry in that old Kansan sea. 



