784 Comparative Morphology of Chordates 



The Primates are very definitely allied to the Insectivora b> the 

 lemurs. Fossils regarded as lemur-like are found in the early Eocene. 

 It is true both of ancient and of existing mammals that there is no 

 sharp anatomic demarcation between those of the insectivore type and 

 the lemuroid primates. The most significant difference is a tendency 

 toward relatively greater size of the lemur's brain and the shortening 

 of the jaws and nasal region. The similarity, and also these differences, 

 are especially well shown by comparison of a lemur with an arboreal 

 insectivore such as a tree shrew (Fig. 600). In fact, the tree shrew 

 might reasonably be regarded as a primate somewhat more primitive 

 than a lemur. 



