MESOZ01C ERA. AGE OF REPTILES. 337 



legs. Still much larger animals of this order have been 

 found in the United States, as we shall see further on. 



3. Pterosaurs, or Winged Sauriaiis. These are per- 

 haps the most extraordinary of all known animals. They 



FlO. 286. Compsognathus, x &. (Restored by Marsh.) 



combined the stout body with keeled breastbone, the long, 

 flexible neck and beaklike jaws of a bird, with the long 

 arms and membranous flying-web of a bat and the essen- 

 tial characters of a reptile. In some cases they had a 

 short, aborted tail, like a bird, but in others a long tail, 

 with vertical expansion at the tip, which was used as a 

 rudder in flying (Fig. 287). The pterosaurs varied in 

 size from two or three feet to eighteen or twenty feet 

 from tip to tip of the extended wings. 



Birds. We have seen that the reptiles of this time 

 approached birds, but still more remarkably do the earliest 

 birds approach reptiles. There is in Bavaria a peculiar 

 limestone used the world over for lithographic drawings. 

 This lithographic limestone is equally celebrated for its 

 marvelous preservation of fossils. In 1862 the oldest 

 known bird, the Archceopteryx, was found there with even 



LE CONTE, GEOL. 22 



