I30 EXTINCT MONSTERS. 



the existence of Pterodactyls during that period fully equal in 

 size. 



But the largest Pterodactyls hail, like so many other big 

 things, from America. Professor Marsh tells us of monsters in 

 his famous collection with a spread of wings of twenty to twenty- 

 five feet ! These large forms had no teeth in their jaws, and 

 their skulls are of a peculiar form. The long-pointed jaws were 

 probably sheathed in horn during life, as in birds (see Fig. 36). 

 According to Marsh, these toothless forms (which he calls 

 Pteranodonts) were mostly of gigantic size. With regard to their 

 food it is almost vain to speculate ; but if they did prey upon 

 fishes, they must have had a capacious mouth and gullet, and 

 must have swallowed their prey whole, after the fashion of pelicans. 

 But we doubt if they had the peculiar pouch possessed by those 

 birds. In the absence of more complete accounts of the large 

 forms the artist has only attempted to restore the small ones. 

 (See Plate XII., showing four different kinds.) 



Whether Pterodactyls were cold-blooded or warm-blooded is 

 a question on which the authorities are not agreed. Professor 

 Owen argued from the absence of feathers that they could 

 not have been warm-blooded. But, in spite of this great 

 authority, who has defended his opinion somewhat strongly, 

 there are others who argue that the amount of work involved in 

 sustaining a Pterodactyl in the air make it highly probable that 

 it was warm-blooded. The absence of feathers to retain the heat 

 of the body need not be regarded as conclusive, for bats are 

 warm-blooded animals, and in their case the heat of the body is 

 retained by a slight downy covering to the skin. Such a covering 

 may have protected the bodies of Pterodactyls, and we could not 

 expect to see any trace of it in the Bavarian specimen of 

 Rhamphorhynchus referred to above. An important fact bearing 

 on this question is the discovery of perforations in the bones of 

 these animals very similar to those seen in birds. Now, birds 

 have a wonderful system of respiration, or breathing. The air 



