THE ANTIQUITY OF THE ANGIOSPERMS 781 



the origin of the angiosperms would thus be thrust back to a date 

 much earlier than the beginning of the Cretaceous. 



Of course such an estimate is hypothetical in the extreme; but 

 by indicating that the history of the woody members of the group 

 extends back over a period many times as long as that during which 

 herbs have existed, it serves to give us a clue as to angiosperm 

 antiquity, and it emphasizes the fact that our present huge array 

 of trees and shrubs, types very slow in changing, must have required 

 an enormous length of time for their evolution. There is evidence, 

 moreover, that evolution took place even more slowly in former 

 times than it does at present, since flower-loving insects, to the 

 agency of which many attribute the rapid development of the 

 angiosperms, did not appear on the scene, at least in numbers, till 

 the dawn of the Tertiary. 1 All this makes it highly probable that 

 these now dominant seed plants did not begin their existence in the 

 early Cretaceous, where they first appear as fossils, but that they 

 had already undergone a long course of evolution before that time. 

 Indeed, the external features, and more particularly the internal 

 anatomy, of these earliest fossil angiosperms are not at all those 

 of primitive types, but exhibit a considerable degree of specializa- 

 tion. 2 To regard such plants as having sprung suddenly into being 

 from gymnospermous ancestors is to overtax the imagination of 

 even an ultra-mutationist. 



As to why the earliest members of the group apparently failed 

 to be preserved we cannot be sure, but evidence is at hand that 

 they were upland forms which would tend less frequently to become 

 fossilized. This predilection of primitive angiosperms for an equa- 

 ble, reasonably cool climate, if it can be proved, will lead us to look 

 back to the era of low temperatures in the Jurassic, or perhaps 

 even to as remote a period as the cataclysmic refrigeration of the 

 Permian, for the date when the first angiospermous stock began 

 to be differentiated from its gymnospermous ancestry. 



The botanical evidence is therefore overwhelmingly in favor of 

 the conclusion that angiosperms existed for a considerable period 



1 Handlirsch, Die fossile Insecten. 



2 M. C. Stopes, "Petrifactions of the Earliest European Angiosperms," Phil. 

 Trans. Royal Society, B, 203, pp. 75-100. 



