medifossetta 



postfossette 



prefossctti 

 entecrochet 



crocfiet 

 FIG. 17-x Typical Rhinoceros molar, showing terminology of the crests and folds. 



metacone- 



metaconule- / -f 



hypocone- 



-protoconule 



protocone 



Fro. 176. Topographic relations of the parts of the typical Rhinoceros molar pattern to the 

 sexitubercular ancestral ground plan. 



faraslytf faraccne mitatone 



parastylc paracone- mttacont 



ftroColoptt m:tatoph 



parastyle paracone ntttatone 



protohpk mttalopk 



prolobpk 



mclaiofk 



mctalophid hypolopkid ItypaanuliJ mclalophid hypoloplmt It? 



nielaloptuii 



liypolopkltt 



Tapiroiil. Lophiodout. Rhinocerotoid. 



(P rot p! r >'.<). (Lii/iiclori). (Hi/rachyux). 



FIG. 177. Typical lophodont molars of Perissodactyls. 



In the Tapirnid type the paracone and metacone are subequal or symmetrical, strongly convex 

 externally. In the Rhinocerotoid type, the paracone is more or less convex, the metacone 

 elongate, externally flattened to concave. The Lophiodont type is intermediate. It is noteworthy 

 that in the Middle Eocene or Bridsjer Stage, the molars of the various Perissodactyls are 

 rather similar. Thus some molars of the Tapirid S;i.<i: i,,,,,l,,,i approach the /'/<'"</,//>/)/'.. type 

 among Equidas, some molars of the Lophiodont H<.lnl' tea approach the lIiii-<K'l,nii.< type ; while tin- 

 latest representatives of Hin-nclii/us show some approach toward the Hi/i-i"-" '< type among 

 Rhinoceroses. 



