I 



1&16] Merriam: Fauna of Cedar Mountain Region 169 



trees, the existence of forest forms like Bassariscus and Aplodontia, 

 and the relative importance of browsing types with rarity of grazing 

 horses, all suggest a slightly more humid climate, with groves or brush 

 areas such as may occur around the borders of the Great Valley of 

 California at the present time. 



STAGE OF EVOLUTION AND RELATIONSHIPS OF 

 THE CEDAR MOUNTAIN FAUNA 



Relation of the Cedar Mountain Fauna to the Tertiary Faunas 

 of the Great Basin. — The faunal assemblage obtained in the Cedar 

 Mountain region shows affinity with the Middle Miocene of Virgin 

 Valley, but most nearly approaches the faunal stage of the Barstow 

 Upper Miocene. It is distinctly older than the Ricardo, Thousand 

 Creek, and Rattlesnake. Several differences between the Cedar Mount- 

 ain and Barstow faunas may be due to geographic variation or may 

 indicate that the Cedar Mountain beds cover a somewhat longer time 

 range, including both older and younger beds than those from which 

 collections have been obtained in the Barstow. 



The Cedar Mountain fauna resembles that of the Middle Miocene 

 Virgin Valley in the presence of a Tephrocyon near kelloggi, Hypo- 

 hippus, Meryehippus, rhinoceroses, and a Mcryodus near furcatus. It 

 differs from the Virgin Valley and Mascall in the presence of Dipoides 

 and Merycodus neeatus; in the more advanced stage of the horses; and 

 so far as known in the quite advanced stage of the Aplodontia-like 

 rodents, of the camels, and of the merycodont near M. furcatus. 



Tephrocyon kelloggi, apparently represented in the Cedar Mountain 

 by a portion of a lower carnassial, was described from the Virgin 

 Valley. A similar form is, however, imperfectly known from the 

 Thousand Creek Pliocene. The Hypohippus and Meryeh ippus of Cedar 

 Mountain are of more advanced types than those of Virgin Valley, 

 and the Merycodus near furcatus is a larger, heavier form than that 

 of Virgin Valley. 



Dipoides is known in the Cedar Mountain beds but has not been 

 found in the Middle Miocene. The Aplodontia-like form in the Cedar 

 Mountain may be a more progressive type than the Aplodontia of 

 Virgin Valley. Some of the fragmentary horse remains are much 

 more specialized than any known from the Middle Miocene, and are 

 even relatively advanced for the Barstow Upper Miocene. The total 



