402 GENERAL ZOOLOGY 



though not necessarily a good flier. It had true feathers, 

 but it was very different from the birds of today in that it 

 possessed teeth and a long, lizard-like tail of about twenty 

 vertebrae. These last characteristics are strikingly reptilian, 

 and such considerations point to the fact that the birds 

 developed from the reptiles. As the development was un- 

 doubtedly gradual, we should expect to find forms possess- 

 ing the characters of both groups. 



Many remains of birds have been found, especially in the 

 rocks on the eastern slope of the Rocky Mountains, in 

 Kansas and Colorado. These belong to species which lived 

 later in the period. These birds are of at least two different 

 types, differing in the arrangement of the teeth. One group 

 had the teeth set in separate sockets; the other had the 

 teeth in grooves. Some of the birds found in the rocks of 

 this age in New Jersey seem to have been toothless, like 

 birds today. It is interesting to note that even thus early 

 the bird type had become quite well advanced, having lost 

 not only the teeth but also the long tail of earlier forms. 

 The time of this period was great enough to permit the de- 

 velopment of species of birds with highly developed wings, 

 as well as others with degenerate wings. 



In the next succeeding period, to which we shall refer at 

 the close of a later chapter, the birds were all toothless and 

 related to those of today. There were woodpeckers, parrots, 

 swallows, cranes, and many others. 



