EXTINCT APES 



287 



claim, the existence of this gibbonlike animal in the Oligocene 

 is necessarily of great theoretic importance. Among other 

 things, it implies still greater antiquity for the Old-World 

 monkeys, although no older Cercopithecidae have yet been 

 discovered. 1 



It is not difficult to picture what these facts mean. The 

 great apes are not new denizens of the jungles. When Europe 

 was tropical and forests grew in Greenland, the immediate 



Eocene. 



Oligocene. Miocene. 



Pleist. 

 and 

 Pliocene. Recent. 



M 







N 



Diagram showing the evolution of certain groups of placental mammals. 



A = line leading to whales, B — to bats, C = to Primates minus Hominidae, D = to deer, E = to 

 elephants, F = to horses, M-N — climax-line, O-P = base-line of placental evolution. 



kindred of the chimpanzee were in existence. They listened to 

 the trumpetings of the dinotherium and the mastodon, and they 

 watched the three-toed hipparion browsing in the glades. 

 Furthermore, the manlike mammals had virtually reached the 

 point in their evolution now represented by the siamang at a 

 time when the ancestors of the elephants had not even acquired 

 their trunk, when the deer were quite hornless, and long before 

 there were any animals that we should think of recognising as 

 horses. Just as bats and whales antedate the apes by long ages, 



1 The oldest known Old-World monkey is Parapithecus, found in the same 

 stratum with Propliopithecus. 



