104 



EVOLUTION OF MAMMALIAN MOLAR TEETH 



third incisors of the Eat Kangaroo (J-Jctto/if/ia). In Aninci/on (p. 133) 

 the crown is depressed but not at all basin-shaped. The molars which 

 gave origin to the Kinetic Microlfst.cs basin-shaped type may, therefore, 

 have been either simply conic or haplodont, or even possibly tritubercular. 



FIG. 52. The outer surface of the right maxilla of So/mlon, from the Middle Purbeck Beds 



(Upper Jurassic, England). XA 



c, 



53. Views of the maxilla of Allodon laticeps, Marsh, seen from below, from the Atlaiitosaurus, 

 Beds (Upper Jurassic, North America), x 4. 



llllJJi ^3 



,s 



FIG. 54. Cldro.r phratuis, Cope, x . a, viewed from below, palate with dentition, three 

 promolars and two molars in situ ; b, viewed from the outer side. From the Torrejon Formation, 

 Basal Eocene, Stage II. New Mexico. After Cope. 



Figs. 52-54. The molar tooth forms of the Multituberculate families 



BolodonticUe, Chirogidte. 



It must be clearly stated, however, that the Microlestes antiquus molar 

 bears no close resemblance to any of these types and there is no clear 

 evidence in the Microlestes molar itself of derivation from the tritubercular 

 type. 



