416 HISTORICAL GEOLOGY 



nent, and in Mexico it is still more conspicuous, for there 

 fault scarps which were made at the close of the Comanchean 

 were base-leveled before the Cretaceous sediments were de- 

 posited. In Europe, also, an unconformity has been observed. 

 From the wide distribution of these conditions, it seems 

 probable that the sea level was drawn down at the close of 

 the Comanchean period, and that the continents were again 

 largely out of water. 



The plants become modernized. Up to this time the 

 vegetable world had been represented entirely by such fossil 

 plants as the ferns, mosses, and cycads, plants which belong 

 to distinctly lower groups than those with which we are now 

 most familiar. In size and abundance they probably com- 

 pared well with our modern trees, shrubs, and grasses, but 

 they were different in structure and aspect. In the Coman- 

 chean period, for the first time, the modern flowering plants 

 made their appearance, and in this case with a suddenness 

 which is yet to-be explained. By the end of the period they 

 had become the most abundant of all plants in America, and 

 later in Europe, and they have continued to hold their su- 

 premacy ever since. It is a significant fact that not long after 

 the advent of the flowering plants came the great rise of the 

 mammals, and also the first appearance of the higher insects, 

 such as the butterflies, bees, and wasps. These animals are, 

 in fact, largely dependent upon the higher types of plant life 

 for their existence, and their rapid development may be due 

 in no small measure to the entrance of the Angiosperms 

 (p. 294). 



Lesser changes among the animals. By a somewhat 

 slower development, the fishes likewise had reached almost 

 their modern position by the close of the Comanchean period. 

 The peculiar and in many respects ill-constructed fishes of the 

 earlier periods, from the Silurian on, were gradually relegated 

 to the background, while the modern Teleosts became the 

 most abundant types, fishes like our modern bass, salmon, 

 and many others, which have well-developed bony skeletons. 



