THE PHYLA HEMICHORDATA AND CHORDATA 



Fig. 18.19. Ancient reptiles. A, 

 restored stceleton of a pterosaur, 

 Rhamphorhynchus, of Jurassic age; 

 this species reached a length of 

 about two feet, soaring on wing 

 membranes supported by the enor- 

 mous fourth digits of the hands. 

 B, restoration of the Lower Cre- 

 taceous dinosaur Iguanodon, the 

 first dinosaur described in scien- 

 tific literature; it was about 30 feet 

 long and was specialized for bi- 

 pedal locomotion. C, restoration 

 of Podokesaurus , a relatively tiny, 

 light-footed dinosaur with many 

 bird-like skeletal characteristics, 

 such as long hind limbs, very elon- 

 gate metatarsals, and hollow 

 bones. (All redrawn after G. 

 Heilmann, The Origin of Birds, 

 copyright 1927 by D. Appleton 

 and Co., printed bv permission of 

 Appleton-Century-Crofts, Inc.) 



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