154 



THE AGE OF MAMMALS 



the whole, it is a very imposing, diversified, and well-balanced fauna, with 

 an equal distribution of arboreal, cursorial, aquatic, fossorial, carnivorous, 

 and herbivorous types. 



? Oreodon. zon6 



Oreodon 

 Cylindrodon 

 > Caenopus 

 Jschyromys 

 Poebro then urn 



Titanotlwriunv zone 



J)iplacodort zo/ze 



Amynodon 



Protoreodon 



Came/id 



? Lanibdotheriunt zone 



Coryphodon, PhenacoduSj Eohippus 

 ? Coryphodon zone 



By permission of the American Museum of Natural History. 



Fig. 55. — Lower Eocene to Oligocene. A composite, continuous section in the Wind River 

 Basin, Wyoming. After Granger, 1910. Compare Fig. 38. 



As above noted, the chief distinction from Europe is in the large pro- 

 portion of surviving archaic Mammalia. Very noteworthy is the presence 

 of an opossum (Peratherium) as indicating the continued residence of 



