South Dakota School of Mines 



Bulletin No. 13. Plate No. 9. 



THE AGE OF MAMMAL.S 



CCNOZOiC, OR TERTIARY AND OUATERNARY. 



WESTERN LAKE BASINS and CHARACTERISTIC MAMMALS' 



RECEHTam 



PLEISTOCENE 

 ■PLIOCENE 



MIOCENE j 



% _ I 



* I 



^ 0UG0C£NE| ;! 

 * ' ' i 



J&fh 



EOCENE 



**» f 



^ CRETACEOUS 



* ! 



AMHLVPOUS C0RYPHO0ON 



Divisions of the Age of Mammals. Characteristic fossil mammals, and 

 the geological formations in which they are found. Matthew, 1903. 



