OUR BEST FEATURES 



last disappear entirely in the mammals. As the 

 brain enlarges these roofing bones are lifted into 

 greater prominence, the frontals, parietals, inter- 

 parietals and occipitals becoming the dominant 

 elements in the great vault of the human skull. 



The superior maxillary bone (Fig. 50) begins as 

 a slender, vertically shallow element, but by the 

 time of the early mammal-like reptiles (Fig. 50 V) 

 it has extended dorsally and gained contact with 

 the nasals. In the mammals (Fig. 50 VII-X) its 

 dominance is still more pronounced; one fork 

 reaches the frontals while another fork finally 

 separates the lacrymal from the jugal and the 

 whole bone becomes shortened antero-horizontally 

 and deepened vertically. In the anthropoids and 

 man the premaxillse early unite with the maxillae. 



The inferior maxillary (dentary) at first is 

 confined to the anterior half of the mandible. In 

 the higher mammal-like reptiles it becomes dom- 

 inant, the post-dentary elements retreating before 

 it. In the earliest mammals the ascending ramus 

 of the dentary effects a new contact with the 

 squamosal, the temporo-mandibular articulation, 

 which is transmitted without further essential 



modification to man. 



87 



