THE LLAMA AND ITS PAST HISTORY 407 



or llamas could have originated. And that is precisely what 

 happened, as already mentioned (p. 86). Towards the 

 latter end of the Eocene Period there appeared four genera 

 in western North America, all of which exhibit decidedly 

 camel-like characters, and Professor Osborn * believes that 

 one of these, the diminutive Protylopus, may possibly repre- 

 sent the most remote ancestor of the grand American phylum 

 of camels. Other genera occur in Oligocene and Miocene beds 

 of North America. During the latter period camels had ap- 

 parently spread in great herds over the continent. It is 

 thus probable that they then extended' their range to other 

 parts of the world. Some of them, like Pliauohenia, had 

 assumed llama-like characters, and as the .western Pacific land- 

 belt was then in communication with California the ances- 

 tors of the South American llamas were able to pass south- 

 ward. According to Professor Osborn llamas survived in 

 North America until Pleistocene times. They were then 

 becoming extinct in the eastern States, lingering on in Cali- 

 fornia where the great sabre-tooth tiger no doubtstalked tjiem. 

 In the Siwalik beds of northern India camels first appear in 

 the Pliocene, as in South America, and it is generally assumed 

 that the ancestors of the Old World camels crossed over to 

 Asia by the Bering Strait land bridge. But as it was probably 

 in Miocene times that these early camels wandered westward 

 from North America, the Bering Strait land bridge had not 

 yet come into existence. They must have utilised the more 

 southern bridge, which I think replaced it in earlier Tertiary 

 times (Fig. 16). 



Recently we have received clear proof of a migration of 

 mammals from Asia to North America, which I think must 

 have taken place across the same Pacific land bridge. One 

 of the most remarkable discoveries among the many note- 

 worthy ones in North American palaeontology is that by Dr. 

 Matthew and Mr. Cookf of Asiatic antelope remains in 

 western Nebraska. The American invasion by true Asiatic 

 antelopes was brilliantly and amply confirmed, according to 

 Professor Osborn, by Mr. Merriam's discovery in Nevada. 



* Osborn, H. F., " Age of Mammals," p. 170. 



t Matthew, W. D., and H. J. Cook, " Pliocene Fauna from Nebraska." 



