THE MIOCENE OF EUROPE, ASIA, AND NORTH AMERICA 



299 



decline. The river-border and forest-living oreo- 

 donts are among the declining types soon to be- 

 come extinct. The browsing tapirs are represented 

 only by a single recorded specimen of Tapiravus. 

 The true browsing or 'giraffe camels' {Altica- 

 melus) so highly characteristic of the Lower and 

 Middle IMiocene have not thus far been discovered 

 at all in the Upper Miocene, although we are certain 

 that these animals were not yet extmct, because 

 remains of them are again found in the Lower Plio- 

 cene Rattlesnake Formation of Oregon. Grazing 

 camels with hypsodont teeth {Procamelus and 

 Pliauchenia) are very abundant and specifically 

 varied. The more primitive hypsodont camel 

 known as Protolabis still survived in Montana. 

 The wide geographic range of these camels in 

 North America is most remarkable. They were 

 certainly present in great herds, and lent the most 

 characteristic aspect to the landscape. Soon after 

 this period they are first recorded in Asia in the 

 Siwaliks of the sub-Himalayas. Among the ru- 

 minants, the brachyodont browsing Dromomeryx 

 and Blastomeryx still survive and are highly char- 

 acteristic. At this time Blastoyneryx first appears 

 with horns. Certain of the rhinoceroses are also 

 of the browsing type, and all the new mastodons 

 must be placed in this category. It is noteworthy that the browsing chaU- 

 cotheres, represented by the giant Ancylotherium of the L^pper Miocene 

 of Europe, have not 

 yet been discovered in 

 North America. The 

 grazing animals are on 

 the whole more numer- 

 ous, more varied, and 

 more characteristic. 



A very typical pro- 

 boscidean is the Trilo- 

 phodon productus, u 

 doubtful specimen of 

 which was discovered 

 by Gidley in the Clar- 

 endon Formation of 



Tovoc Til -li 11 f ^'^*' ^'^'^- — Skull of the primitive four-tusked mastodon, 



XCXas. i ne SKUU OI Trilophodon productus, of the Upper Mioceue of Texas. In the 

 thib^mastodon is broad American Museum of Natural History. 



Prevailing Mammals 



Horses 



Hypohippus 



Parahippus 



Meryckippus 



Protohippus 



Neohipparion 

 Peccaries 



Prosthennops 

 Oreodonts 



Pronomotherium 



Merycocharus 

 Camels 



Procamelus 



Pliauchenia 

 Deer 



Blastomeryx 



(horned) 



Merycodonts 

 Cavicornia 



Dromomeryx 

 Canids 

 Procyonids 

 Felids 



Machserodonts 



