154 



EVOLUTION OF MAMMALIAN MOLAR TEETH 



Creodonts, can, on the other hand, be regarded as the ancestors of 

 a part, at least, of the Edentates ; to the extent that in such a line 

 the formation of prismatic teeth out of the tritubercular and tuberculo- 

 sectorial type can be traced. 1 



FIG. 121. Side and top views of the skill of PsMacoth<rii<m multifraguw, family Stylino- 

 dontidre, order Tteniodonta, from the Torrejon Formation, Stage II., Basal Eocene, showing the 

 enlarged gnawing canines, x ^. (From Wortman, after Scott and Osborn.) 



To this group Wortman 1 gave the name Ganodonta (equivalent to 

 Tamiodonta Cope) in reference to their enamelled teeth. 



All the early members of this group of Ta-niodonta have tubercu- 

 late teeth, in which, however, the enamel is so delicate that it rapidly 

 wears off. In Psittacotherium, for example, the lower teeth are 

 ([uadritubercular (Fig. 123), in Calamodon (Fig. 124) the unworn lower 

 teeth are crested and exhibit all the five cusps (proto-, meta-, hypo-, 

 entoconids, and hypoconulid) of the primitive crown, having completely 

 lost, however, the paraconid. In the remotely related Onycliodcch-x 

 (Figs. 118, 119) the upper molars are again strictly tritubercular, while 



1 Wortman, J. L., " The Ganodonta and their Relationship to the Edentata," Bull. Amer. 

 J/H.S. Nat. Hist., Vol. IX., 1897, pp. 59-110. 



