50 



MAMMALIAN DENTITION 



In Sesamodon (Fig. 11) as restored by Broom we see a Rep- 

 tile in certain respects even more mammalian in appearance 

 than Bauria. In this Cynodont the lower canine was long 

 enough probably to overlap the maxilla when the jaws were 

 closed; the first upper postcanine tooth is more conical than 

 those succeeding it and illustrates the varying characters of 

 the cheek teeth for which however we shall do better 1 to con- 



rig. 12. — A. Palatal view of left maxilla of Diademodon mastacus. (After Seeley.) 

 B. Lateral view of the left dentary of Diademodon mastacus with occlusal view of the 

 seven lower molars of the right side. (After Broom.) Note the tubercular character 

 of the crown, the elevation of the lateral cusps and the transverse elongation of the 

 single roots of the maxillary teeth. In the mandibular molars note the smaller rounded 

 crown and the single transverse ridge on the occlusal surface. 



stilt the illustration of Diademodon; the zygomatic is more 

 powerfully built and sends a process upward; the mandibular 

 articulation permits limited antero-posterior movement which is 

 probablj T to be associated with the flat thick crowns of the 



