152 



EVOLUTION OF MAMMALIAN MOLAR TEETH 



pointing toward such ancestry was recorded by Thomas 1 in the vestigial 

 milk teeth of Orycteropm, the posterior milk molar retaining a simple 

 crown with two roots. 



ff 



Fin. 117. A. Skull of Conoryctes comma, family Conoryctidse, order Tseniodonta, from the 

 Torrejon Formation, Stage II. Basal Eocene, New Mexico. 



B. Superior view, lower teeth. 



6*. Superior view, upper teeth. The upper teeth show apparent traces of tritubercular deriva- 

 tion, the lower of tuberculo-sectorial derivation, x j. (From Wortman, after Scott and Osborn.) 



FIG. 118. Upper cheek teeth of Owichodectes tissonensis, family Conoryctidie, order Tsenio- 

 donta, from the Puerco Formation, Stage I. Basal Eocene, New Mexico. 



A. Outer side view. B. Crown view. C. Inner or lingual side view. The molar teeth are 

 obviously tritubercular, suggesting those of the Oxyclrenid Creodonts (Fig. 84). x+. (From 

 Wortman, after Scott and Osborn.) 



It has, of course, been generally assumed that in the ancestors of 

 the Edentates, the molar teeth were not only rooted and covered with 

 enamel, but that they possessed a more complicated pattern of the 

 crown. 



1 "A Milk Dentition in Orycteropus," Proc. Roy. Soc., Vol. XLVIL, 1890, pp. 246-248, 

 PI. S. 



