Epilogue: What Conies of Studying Vertebrates 



793 



reptiles and the more recent birds, no one animal could better satisfy 

 requirements than the feathered flying reptile — or, because of feathers, 

 call it a bird — Archaeopteryx. Because of their aerial habits, birds did 

 not come into serious competition with mammals. The two groups have 

 come down through tens of millions of years as flourishing contempo- 

 raries. Some mammals prey on birds and some large birds prey on 

 small mammals, but this reciprocal eating is no more than a mutually 

 advantageous relationship between the two groups. 



From the early (Tertiary) Cenozoic time down to the present has 

 been traced a line of mammals primitively of small size and quite in- 

 different anatomic characteristics, the Insectivora. At a remotely 

 ancient time in the history of this line, it evidently gave rise to a branch 

 along which adaptation for arboreal life was acquired. In most respects 

 the animals retained the insectivore characteristics, but the forelegs 

 became elongated and the digits were adapted for grasping, making 

 possible a novel method of locomotion — swinging by the forelegs 

 ("arms") from branch to branch of trees. In some of the more recent 

 animals along this primate line, a considerable increase in the size 

 of the body occurred, while the brain attained a size greater than can 



Fig. 602. Relationships of the primates. Copied, with minor modifications, 

 from a "tree" which forms the background of a portrait of Robert M. Yerkes, 

 founder of The Yerkes Laboratories of Primate Biology, Inc. The "tree" of the 

 portrait is the painter's artistic elaboration of a figure published by William Patten 

 in 1930. 



