THE HISTORY OF LIFE 



and the insertion of its teeth in special sockets. Speci- 

 mens of these creatures measure forty-five feet in 

 length. Another extraordinary form was a flying 

 reptile huge, winged, bat-like creatures, with large 

 heads, teeth in distinct sockets, eyes with bony plates 

 round the eyeball, and bones like those of birds, hollow 

 and air-filled. One type had a short tail, and jaws fur- 

 nished from end to end with long teeth. Some types 

 possessed a long tail, and formidable jaws terminating 

 in a horny beak these strange harpy-like creatures 

 were able to fly, to shuffle on land, to perch on rocks, 

 perhaps even to dive in search of their prey. The long 

 slender teeth which some of them possessed indicate 

 that they lived on fish. These monsters attained, when 

 these strata were formed, their maximum development. 

 Some of the Jurassic reptiles must have weighed about 

 three tons, others reached a height of ten feet and a 

 length of fifty feet. One species of these gigantic 

 creatures had feet which spread out a square yard in 

 area. Some had bony plates on their backs measuring 

 more than three feet in diameter. In America 

 remains of these giants have been found thirty feet 

 or more in height, and with a length of nearly 100 

 feet. 



Now the first bird appears, a creature somewhat 

 smaller than a crow, imitating the characters of a reptile 

 and a bird ; thus, it had a long lizard-like tail, each 

 division bearing a pair of quill feathers. The three 

 wing fingers were free, each ending in a claw ; there 

 were four toes to each foot as in our common birds. 

 The jaws carried true teeth. 



Small marsupials, creatures which deliver immature 

 young, which were nursed in a pouched cavity as in our 



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