LECTURES IN BIOLOGICAL SCIENCES 



they were also skillful in climbing trees and perhaps occasion- 

 ally stood semierect on their hind feet. 



I am going to assume that Proconsul was an ape, that is, a 

 member of the pongid family along with the living great apes— 

 the gibbon, chimpanzee, orangutan, and gorilla— and the fossil 

 apes like Dryopiihecus. The apes are sufficiently diverse in 

 morphology to warrant their placement in three subfamil es: 

 (a) the hylobatine for the gibbons with a history back to the 

 Oligocene; (b) the proconsuline; and (c) the pongine for the 

 living great apes and their ancestors, like Sivapithecus and Dry- 

 opithecus, back to the Miocene. 



The proconsulines lack certain specialized features of the 

 pongines. Their teeth are more primitive, they have no simian 

 shelf uniting on the inside of the two halves of the lower jaw, 

 they lack the large brow ridges of the living great apes, and their 

 trunk and limbs retain features of a generalized quadrupedal 

 primate rather than the specialized features of the arboreal 

 pongines. Proconsul offers the best evidence now available as 

 to what our Miocene ancestors may have looked like. It is 

 almost certain— as certain as a negative can be— that they did not 

 manufacture tools and that they did not symbol. 



2. Middle Miocene to Pliocene Hominoids 



Lack of recovered fossils forces us to leave a blank, or sev- 

 eral blanks, for genera representing a period of some twenty- 

 four million years in the hominid branch of hominoid phylog- 

 eny. Young students who wish to make paleontological history 

 might well look for representatives of these genera. If hominoid 

 genera evolved at the same rate as equine genera in the Miocene 

 and Pliocene, we may hope to find at least three now unknown 

 genera in the hominid phyletic line. Unfortunately fossiliferous 

 Pliocene deposits are rare in Africa, which is the most promising 

 place to look. 



Hurzeler (1958) and some other investigators insist that 

 Oreopithecus fills one of the Pliocene blanks. Thanks to Hur- 

 zeler, we now have a much flattened but almost complete skel- 

 eton of Oreopithecus from the Pliocene lignite deposits of Tus- 

 cany in central Italy. When this 1958 find is fully described, 

 we will have a better idea of its phylogenetic placement than 



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