166 



THE AGE OF MAMMALS 



coarse, fluviatile materials and contain but few fossils, including Dino- 

 cerata, the rhinoceroses (Amynodon), and Triplopus (an excessively light- 

 limbed hyracodont), the aberrant titanotheres Sphenocoelus and Metarhinus. 

 The latter titanothere appears to be a dwarf and possibly aquatic or river- 

 frequenting form, hence the specific name, M. fluviatilis. 



Upper Eocene, as Represented in the Upper Washakie and Middle and 

 Upper Uinta. The Ludian Stage 



Upper Washakie : Eobasileus Zone. — In these famous beds, constitut- 

 ing the Haystack Mountain, or Mammoth Buttes (Fig. 59) of Cope's 



Fig. 66. — The Upper Eocene KohasUcus, the four-horned amblypod, last representative of 

 its race. To the left a female, with small horns and tusks ; to the right a male with large 

 horns and tusks. After original by Charles R. Knight in the American Museum of Natural 

 History. 



descriptions, the archaic fauna is distinguished by the final evolution of 

 the Amblypoda into giant specialized Dinocerata, including the extremely 

 long-headed form, Eobasileus ( = ' Loxolophodon') of Cope.^ Eobasileus 

 (Fig. 66) represents a distinct phylum of amblypods, as shown by the more 

 posterior position of the front pair of horns and the consequent great elon- 

 gation of the snout; in Tinoceras the front horns are more anterior in 

 position, and the snout is thus relatively shorter, the proportions of the 



' The type of the genus Tinoceras, namely, the species T. anceps is from the Upper Bridger, 

 Sage Creek, Horizon C. The type of the species T. ingens is probably from the Lower Washakie. 

 (W. D. M. 1909). 



