REPTILIA 



211 



side. The reptiles are doomed. Between the birds of the air and the 

 beasts of the field and forest, and especially at the hand of that super- 

 mammal, Man, who seems to have centered his aversion upon the ser- 

 pents, the reptiles are destined to oblivion, except in so far as Man 

 sees fit to preserve certain types for his own uses. No mere verbal 



Fig. 121. — Chart, showing origin and adaptive radiation of the reptiles. Dotted 

 areas represent existing groups, black areas, extinct groups. This chart also 

 shows the origin of the birds and mammals from reptilian stock. In the cases of 

 several modern groups (Chelonia, egg-laying mammals, placental mammals, 

 Sphenodon and Crocodiles) the dotted areas should reach the top. (After Os- 

 born's " Origin and Evolution of Life.") 



description shows so vividly the origin and adaptive radiation of rep- 

 tiles as does the accompanying chart (Fig. 121). 



From the dawn of the reptiles during the Palaeozoic up to the pres- 

 ent there have passed between fifteen and twenty millions of years, 

 an immense period as compared with the brief span of Man's life upon 

 the globe. The history of the rise and fall of the reptilian empire is 

 one of giant proportions and of intense dramatic interest. Only the 

 vertebrate palaeontologist is in a position adequately to picture this 

 drama for us. 



EVOLUTIONAHY ADVANCES MaDE BY THE REPTILES 



"The environment of the ancestor of all the reptiles," says Os- 

 bom, " was a warm, terrestrial, and semi-arid region, favorable to a 

 sensitive nervous system, alert motions, scaly armature, slender limbs, 



