96 EVOLUTION IN THE PAST 



Jurassic flying lizards were furnished with teeth ; and they 

 subsisted, no doubt, chiefly on fish ; but dragon-flies and other 

 large insects were not despised. The animals varied in size ; 

 some being no bigger than sparrows (P. spectabilis) ; whilst 

 others were as large as rooks (Rhamphorhynchus, P. crassi- 

 rostris), and herons (Dimorphodori). Some species possessed 

 long tails, designed, it may be supposed, chiefly for steering 

 purposes (Rhamphorhynchus}. The long tail, it would seem, 

 proved inconvenient, for apparently no forms in the next 

 Period possessed the apparatus. 



BIRDS Towards the close of the Jurassic more important invaders 

 of the air were in existence than flying lizards ; for there 

 is no doubt that on the site of Europe birds were then in 

 being. They differed in some important respects from 

 modern birds ; but they were well- developed creatures. 

 There is, therefore, no doubt that although they are the 

 first known birds, they must have been preceded by many 

 other forms. Their descent is lost in obscurity. They may 

 have come down from some small Triassic Dinosaurs ; or 

 there may at one time have been a common stock from which 

 birds and dinosaurs emerged. 



The remains found consist of a few skeletons, and im- 

 pressions of feathers ; and all belong to one genus (Arch&op- 

 teryx). In body these creatures were about the size o'f 

 crows. The wing was small, but did not greatly differ from 

 that of a living bird. The thumb, however, was developed 

 as a claw ; and the two surviving fingers, although support- 

 ing some of the flight feathers, were not joined together as 

 with modern birds ; and were, moreover, armed with claws. 

 The bony tail longer than the body was a most remarkable 

 feature. It consisted of twenty joints, each of which 

 supported a pair of feathers. It was, in fact, a reptile's tail, 

 decorated with feathers : and very different, of course, from 

 the bony stump, and fan-like arranged plumage which 

 constitute the tail of present-day birds. These strange 

 creatures were also remarkable in possessing teeth another 

 feature connecting them with reptiles. The body was not 

 lightened, as with modern birds, by a framework of hollow 

 bones, and this fact, taken in connection with the small size 



