THE EOCENE OF EUROPE AND NORTH AMERICA 



169 



recorded in the Upper Washakie. Among the modernized or progressive 

 Carnivora the first true dogs (Canidae) are reported here {Procynodidis). 

 Altogether these beds closely agree with the Upper Washakie, and together 

 may be considered as constituting the base of the Upper Eocene. 



Upper Uinta: Diplacodon Zone. — These upper or true Uinta beds 

 were named by Marsh ' in 1877 as the site of an important stage in the 



U 



ot 



us A 



-J o 

 o 



c 



600 ' 



Diplacodon. 

 zone 



Diplacodon 



Art'iodactyla and chief collection 

 of Uinta mammals(small) 

 ■ Dipl acodon 



(. Dolichorhinus cornutus, 



chief fossiliferous le^el 

 Amynodon 



Eohasileas 



zone Metarhinus 



Chief fossiliferous level 

 Metarhinus 



By permission ot tlie U.S. Geological Survey. 



Fig. 69. — Scale section of the Middle and Upper Eocene of the Uinta Basin. 



After Peterson. 



evolution of the titanotheres, the genus Diplacodon. Here too is found a 

 robust titanothere known as Protitanotherium, which is intermediate be- 

 tween Manteoceras and the horned titanotheres of the Lower Oligocene; 

 in this animal the horns are prominent, oval, osseous projections at the junc- 

 tion of the frontal and nasal l^ones. Altogether three or four phyla of 

 titanotheres occur here, including animals equal in size to the largest exist- 

 ing rhinoceroses. Thus it would appear that after the extinction of the 

 Dinocerata the titanotheres at once became the dominant quadrupeds of 



' Marsh, Introduction and Succession of Vertebrate Life in America. Ainer. Jour. Sci., 

 ser. .3, Vol. IX, 1877, pp. 337-378. 



