350 



ANIMAL BIOLOGY 



reached the colossal size and often grotesque form that 

 gave to this epoch the name of the age of reptiles. Great 

 monsters stalked in the land, enormous creatures swam 

 in the seas, and numerous queer looking pterodactyls 

 flew in the air; but in the following epochs these great 

 creatures all became extinct. The earliest bird of which 

 there is record is a curious creature nearly as much reptile 

 as bird, called the Archaeopteryx. Unlike all existing 

 birds it had a long tail with many vertebrae, and its jaws 



PIG. 239. Skeleton of a cretaceous dinosaur, Triceratops prorsus in the 

 U. S. National Museum. (After Gilmore.) 



were set with numerous conical teeth. It was covered 

 with feathers, and had undoubted wings, but the wing 

 bones were much more like those of typical fore leg 

 than they are in our modern birds. It had been held 

 before that birds sprang from reptilian ancestors, and the 

 discovery of the Archaeopteryx afforded a connecting link 

 which confirmed this opinion. A few other birds with 

 teeth are found in later strata, but their general structure 



