PHYLOGENY 



age, the oldest epoch of the Cenozoic Era. From this remote time, near the 

 beginning of the Age of Mammals, the skulls of small mammals suggesting 

 affinities with tree shrews have been discovered. The structure of the 

 molar teeth of these fossils is primate in character, and there is a tendency 

 toward expansion of the brain. The family Plesiadapidae has been erected 

 for these early Primates. 



Lemurs first appear in the record in the Eocene epoch, from which age 

 records have been found both in Europe ( genus Adapis ) and in America 

 (genus Notharctus) . These were comparable in size to modern lemurs, 

 but the brain was smaller, and they had not yet formed certain specializa- 



FiGUHK 64. Skulls of Primitive Primates, Showing a Morphological (but not 



PHYLOGENE'nC ) TRANSITION FROM TrEE ShREW ThROUGH LeMUR AND TaRSIER TO 



Monkey. A, tree shrew, Ptilocercus; B, mouse lemur, Microcebus; C, an Eocene tarsier, 

 Necrolcmur; D, the modern tarsier, Tarsius; E, marmoset, a phityrrhine monkey, Cal- 

 lithrix. ( From Clark, "The History of the Primates," 3rd Ed., British Museum of Nat- 

 ural History, 1953. ) 



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