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aiiiinals were the marked feature of the life of 

 the time. 



The Cretaceous period is distinguished by 

 the abundance of great marine reptiles, by the 

 presence of pterodactyls and some groups of 

 dinosaurs, and by the final extinction of all 

 these groups of animals. 



Bony fishes came into prominence, as well as 

 sharks of modern types ; the first known birds, 

 so far as this continent is concerned, make their 

 appearance ; and mammals were apparently not 

 uncommon in some localities. But these were 

 insignificant in size, and formed an unimportant 

 feature in the life of North America. 



Vegetation had progressed with the animals, 

 and in the upper beds are found such familiar 

 forms as sycamores, tulip-trees, and magnolias, 

 the general aspect of the forests being not un- 

 like those of our Southern States. This in 

 spite of the existence of true palms, which ap- 

 pear in the Upper Cretaceous, while cycads con- 

 tinue to lend a tropical coloring to the flora, 

 although these plants are by no means so nu- 

 merous as in the Jurassic. 

 15 217 



