272 



TITANOTHERES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



CORRELATION OF DIMENSIONS OF UPPER AND LOWER 

 TEETH 



In considering the generic and specific relations of 

 isolated upper or lower jaws, it is frequently desirable 

 to estimate some of the dimensions of unknown upper 

 teeth from corresponding dimensions of the lower 

 teeth and vice versa. The following table of equa- 

 tions of measurements, prepared by W. K. Gregory, 

 was based primarily upon the type of Telmatherium 

 cultridens but has been verified as to other titano there s. 



Dimensions in the upper row of teeth (anteroposterior measure- 

 ment) approximately equal to dimensions in the lower row 



M '-111^ = tip paraconid mi to tip entoconid 1113. 

 P'-p* = hinder border pi to tip protoconid mi. 

 P2-p'' = tip protoconid p2 to tip protoconid mi. 

 P* = tip protoconid p4 to tip protoconid mi. 

 M' = tip protoconid mi to tip protoconid m2. 

 M2 = tip protoconid mj to tip protoconid ms. 



M3 = tip protoconid ms to tip hypoconulid mi. 



Tip metacone (tritooone) p'' to tip metastyle m^ = anterior border 



mi to tip hypoconulid ms. 

 Tip paracone m' to tip paracone m^ = tip metaconid mi to tip 



metaconid ms. 

 Tip parastyle m' to tip parastyle m3 = tip protoconid mi to tip 



protoconid mj. 



Some of these correlations have been frequently 

 used in the identification of Eocene and Oligocene 

 titanotheres, but they are equally applicable to many 

 other groups of mammals, because they are based 

 upon constant interlocking relations of the cusps in 

 the upper and lower molars. 



GEOLOGIC SUCCESSION AND GEOGRAPHIC DISTRIBUTION 

 OF THE EOCENE TITANOTHERES 



The following table shows the geologic succession 

 and geographic distribution of the Eocene titanotheres 

 as known in 1914: 



Geologic succession and distribution of the species of Eocene titanotheres 



[See flg. 41, p. 59) 



