ORDINAL TYPKS OF MOLARS: CARNIVORA 



137 



transformation of two cusps (paraconid and protoconid) at the expense or 

 degeneration of four cusps (metaconid, hypoconid, hypoconulid, entoconid). 

 Carnassial specialization in general involves the great reduction 

 of a number of elements. It is thus diametrically the reverse of 

 certain types of herbivorous specialization, in which there is a 

 constant increase of the number of elements. 



Fio 93. Upper and lower teeth of a Fissipede or true Carnivore, the Lion. Carnassial 

 teeth '*, (fourth upper premolar and first lower molar). After Matthew. 



pa. 



me 



pa., me. 



D 



FIG. 94. Evolution of the sectorial upper and lower molars in the Creodonts. A. Typu-.il 

 tritubercular upper and tuberculoscctorial lower molars in 7Y<V.,,, ./.,,/ heilprinianus, family 

 Mesonychidse, Puerco Formation. Stage I., Basal Eocene. B. S<'."v>" opigtJwtoma, family Hyit-no- 

 dontida'. Wasatch Formation Lower Eocene. Note: the shearing modification of the posterior 

 side of the upper molar and of the anteruinternal side of the lower molar, the small si/.e of the 

 taloiiid, the reduction of the metaconid. ('. O.fini.-im fordpata, familj- Oxy;i'nid:e, Wasatch 

 Formation. Note the further accentuation of the characters mentioned under K. D. Ptir<i<in,> 

 dasyuroides, family Hyasnodontida:, Upper Eocene and Oligocene, France. Xot<-: the con- 

 crescence of the metacone with the paraeone, the loss of the metaconid, and (almost) of the 

 talonid (hyl), the anterior shifting of the protocone, the lateral compnjssimi ,,f tin- ]..\vor to,.tli. 

 E. Hi/itiiini'1,1 Iwrridus, family Hysenodontidse, White River Formation, Oligocene. Completed 

 carnassial modification, resulting in long shearing blades, in the upper sectorial o imposed of the 

 paracone, vestigial metacone and enlargi-l m.-tastyle ; iu the lower sectorial of the enlarged para- 

 conid and protoconid. All the figures represent the first upper molar (./- 1 ) and the second lower 

 molar (nt. 2 ). From Scott and Osborn. 



