90 THE OPEN BOOK OF NATURE 
which wingless reptiles could not hope to get, and 
they would have excellent means of escape when 
attacked. The competition for the means of life 
must have been exceedingly keen among the swarms 
Fig. 34.—SKELETON OF PTERODACTYLE FROM JURASSIC ROCKS. 
: 
A=appearance the animal would present when alive. 
of reptiles of the Mesozoic Era. Reptilian forms of 
life became less numerous in Cretaceous times, and 
their dominion of the earth was even then doomed. 
The Mammals were destined to become the rulers, 
