454 THE AGE OF MAMMALS 



Quaternary deposits of Kansas of Elephas [columhi] primigenius remains, 

 the characteristic species of the Equus Zone, the conclusion is that the 

 prevailing superficial deposits belong to this formation. The author con- 

 cludes by regarding the Pleistocene mammals of Kansas as probably con- 

 temporaneous. 



There are many reasons, however, why we should consider certain de- 

 posits of the Equus fauna as earlier than the Megalonyx fauna. When we 

 compare the mammals found at Hay Springs, northwestern Nebraska, 

 Rock Creek, Texas, Silver Lake, Oregon, and Peace Creek, Florida, we find 

 many points of similarity, such as the association of many mammals which 

 do not appear together in later formations, and the absence of others which 

 have apparently not yet reached America. 



The solution undoubtedly is that the so-called 'Equus Zone' faunas in 

 different localities are not synchronous, but represent an enormously long 

 period of time, some of early and some of mid-Pleistocene age, some pre- 

 ceding and some contemporaneous with the ' Megalonyx Zone ' faunas. 

 The 'Equus Zone' is accordingly divided here into (1) early phases, p. 

 454, and (2) late phases, p. 461. 



(1.) Early Phases of the Equus Zone 



These early phases are apparently distinguished by the presence of true 

 camels and by the absence of bison (Bisofi). Contradictory to this state- 

 ment is the fact that Bison is recorded at Peace Creek. 



The western and southwestern plains life of the early phase may be 

 summarized as follows: 



Horses, very abundant and characteristic. 



True camels, as well as llamas, abundant in the west and southeast. 



Columbian mammoths, abundant. 



Imperial mammoths, not certainly determined in the north, probably 

 present in the south. 



The earliest prong-horn antelopes (Antilocapra) , abundant on the 

 Great Plains. 



The last of the merycodonts (Capromeryx). 



Peccaries of the genus Platygo?ius, not Dicotyles. 



Mylodont sloths {Paramylodon), abundant in the west and south- 

 east. 



Glyptodonts, or armored edentates, in the south. 



The giant beaver, Castoro'ides, making its first appearance. 



The badger, Taxidea, first appearing. 



Machaerodonts, or saber-tooths, very numerous. 



No other large felines. 



Dinocyons, or amphicyonine dogs, doubtfully present. 



