i 3 4 EVOLUTION OF THE EARTH 



jaw or even the entire creature as the imagination conjures 



it up. 



The archaic mammals. Dinosaurian extinction heralded 

 the expansion of the mammals, and thus the basic cause of the 

 overthrow of the reptilian dynasty, the Laramide revolution, 

 was the enabling act in the evolution of the higher race. 

 Nature now began once more to people land and sea with 

 beasts of diverse sorts, both small and great; but it was only 

 the warm-blooded furry forms whose privilege it was thus 

 to expand. 



The first attempt, following hard upon the dinosaurian ex- 

 tinction, proved to be brief of duration, as though Nature took 

 the stock she had at hand without waiting for the coming of 

 more plastic types. These creatures of the first mammalian 

 expansion have been called archaic, in that while capable of a 

 certain degree of specialization, they were more or less static 

 in three very essential structures; feet, teeth, and brain. Cer- 

 tain ofthem wereTierbivores, some light-limbed, fairly speedy, 

 suggestive of the later cursorial ungulates, although never 

 attaining perfection as speed-adapted types. These were the 

 condylarths (PL IV, A). Others were slow-moving, ponder- 

 ous forms relying upon weapons rather than upon fleetness for 

 defense. Among these latter, the amblypods, were the swamp- 

 dwelling Coryphodon (PL IV, B) and the later Dinocerata 

 (PL IV, C), with conservative molar teeth and feet and ab- 

 surdly small brain, coupled with elephantine bulk and propor- 

 tions of body and limbs, but with what was superficially a 

 highly specialized skull having many horn-like prominences 

 and sabre-like canine teeth a veneer of specialization over a 

 primitive type. 



The flesh-eaters were in some respects better equipped than 

 their plant-feeding contemporaries, but they, like the others, 

 were, if one may judge from skull capacity, notoriously dull and 



