ORDINAL TYPES OF MOLARS: CARNIVOUA 



133 



Molar evolution in the Creodonts follows three general lines : h'rst, 

 development of carnassial teeth as an adaptation in the purely 

 carnivorous forms (Figs. 90, ( .-)l); second, 

 the persistence of more hlunt trituber- 

 cular teeth in the omnivorous forms 

 (Figs. 84, 85) ; third, development of 

 irregularly low-crowned teeth in certain 

 very specialized omnivorous forms, as in 

 Arctocyon and Anacodon (Fig. 86). The 



1 i i P ,1 ,1 -i cusp from the basal cingulum. 



low, irregular molars of the third type 



are so specialized in Anacodon that the primitive tritubercular pattern 



is vanishing; but in the less specialized Arctocyon and the still less 



specialized Clcenodon, the tritubercular origin of these teeth is perfectly 



apparent. 



FIG. 85. Upper teeth of Deltnthi rium fun- 

 daminis, an < >xyel;enid Creodont from the 

 Torrojon Formation, Basal Eocene, Stage III. 

 x 1. The hypocone is developing as a small 



B 



FIG. 86. C, Crown view, p4. m 3 o f Anacodon ui-sii.li as, family Arctocyonidfe, of the Creodonta, 

 from the Wasatch Formation, Lower Eocene, x%. Note the secondary obscurement of the 

 tritubercular pattern by the upgrowth of the basal cingulum, especially in the region of the 

 hypocone, the flattening of the crown (compare the side view B), the wrinkling of the surface. 

 Analogous conditions are seen in the Gorilla and the Bears. 



3 



FIG. 87. Upper ami lower teeth of Dissacus s<i.ui-(i!h"ii/u'x. a Mesonychid Creodont, from the 

 Basal Eocene (Torrejon). The upper molars differ from those of the majority of the c< intern) n>r.-iry 

 Creodonts in the small size of the metueone, the ledge-like character of the protocone; the lower 

 molars are laterally compressed, subtrenchant, with greatly reduced metaconid. They have 

 bean cited by Lr. Wortman as favouring the premular analogy theory. (See j'a-e I'll''. ) 



