0o6 



THE PRIMATES 



XXIII. 2- 



mobility is provided by improving the joints between radius and 

 ulna and humerus at which movements of pronation-supination 

 take place. 



The primates early ceased to feed only on insects, and took to a 

 mixed diet; the teeth have not become so specialized as in ungulate 

 mammals. The hands are frequently and ingeniously used to obtain 



Fig. 383. Upper and lower dentition. A. Modern lemur, Lemur 

 varius. B, Fossil adapid, Notharctus osborni. c, Tarsius, Tarsius 

 spectrum, D, Platyrrhine monkey, Cebus. E. Catarrhine monkey, 

 Macaca. (After Le Gros Clark.) 



food. Omnivorous or frugivorous diets are common, and the molars 

 have become quadritubercular (Fig. 383), the upper adding a hypo- 

 cone and the lower losing the paraconid of the original pattern, leaving 

 the metaconid and protoconid, while the hypoconid and entoconid 

 become raised to make a posterior pair, sometimes with addition of 

 a fifth cusp, the hypoconulid, posteriorly. The cusps are usually not 

 of the sharp insectivorous type, but are low (bunodont) cones and 

 extra ones may be added, or the cusps joined to make ridges. These 

 changes are associated with the adoption by many primates of a diet 

 of fruit or leaves, requiring treatment by biting and grinding. 



The method of reproduction is one of the most characteristic of 

 primate features. The uterus retains signs of its double nature in the 

 earlier types but later becomes a single chamber. The number of 



