138 THE WHITE RIVER BADLANDS 



more complete remains of this genus have been found than 

 that of any other Miocene camel. The accompanying sketch 

 by Peterson, page 71, shows a number of the skeletons 

 as they were found in the quarry. These graceful llama-like 

 little camels lived apparently in herds in an upland country 

 where hard grasses constituted their chief food. In general 

 it may be said that the Miocene forms became increasingly 

 more cameloid in that they are larger, the side toes disappear, 

 the metatarsal bones become more fully united and rugosi- 

 ties of the hoof bones indicate the presence of a small foot 

 pad. 



With the close of the Miocene important geographical 

 changes came about including the raising of the isthmus of 

 Panama above sea level and the forming of a land connec- 

 tion across Behring Strait. In this way widespread migra- 

 tion became possible. The camels during and immediately 

 subsequent to the development of these land bridges were 

 especially abundant and diversified throughout North 

 America, hence readily took advantage of the opportunity 

 to enter South America in the one direction and Asia and 

 thence to Europe and Africa in the other. Later during 

 Pleistocene time by reason of unfavorable climate or other 

 conditions the North American branches of the family all 

 died out while some at least of the more favorably situated 

 foreign members lived on. Thus in the light of their an- 

 cestral history the wide separation of such nearly related 

 animals as the camel and the llama, so long a perplexing 

 question, is readily understood. 



CERVIDAE 



Until 1904 nothing was known of the ancestral deer 

 within the region of the White River badlands. In that 

 year Mr. Matthew described a fragmentary jaw, Blasto- 

 meryx wellsi from the Upper Miocene. Since then several 

 other species have been noted. 



The earliest material obtained gave little information 

 as to the definite relation of Blastomeryx to present rumin- 

 ants but in the study of the later collections Mr. Matthew 

 discovered it to be a primitive deer approximately ances- 

 tral to the American Cervidae and derivable in its turn 

 from the Oligocene genus Leptomeryx whose relation to the 

 Cervidae had not before been suspected. Its nearest relative 



