476 



THE AGE OF MAMMALS 



states. The glaciation on this coast occurred comparatively late in Pleistocene 

 times, and was of the Alpine type, that is, confined to the higher mountain 

 levels. It is quite possible, therefore, that many kinds of mammals, such 

 as the elephants and camels, survived in the comparatively mild climate of 

 the Pacific after they had become extinct in more easterly regions. These 

 suggestions are made in the course of the admirable studies of Merriam, 

 Sinclair, and Furlong (1 903-1 90G) on the very rich fauna of Potter Creek 

 Cave in Shasta County. The life here is quite as varied as that of Port 

 Kennedy, but there are many more still existing species. Out of thirty- 

 seven genera and forty-nine 

 species of mammals, eight 

 genera and twenty-two species 

 are known to be extinct, while 

 thirty of the genera and twenty- 

 two of the species correspond 

 with living forms. The now 

 extinct forms found in this 

 cave are the giant bear {Arcto- 

 therium), peccaries, camels, 

 ground sloths, mastodons, 

 mammoths, and the horses. 

 This includes the entire large 

 fauna, excepting the Virginia 

 deer. The living forms found 

 in this cave embrace nearly 

 the entire existing mammalian 

 fauna of northern California, 

 Oregon, and Washington, with the exception of the mountain sheep {Ovis 

 montana) and the wapiti (Cervus), neither of which occur in the Potter 

 Creek deposits. Conspicuous among the new arrivals is the mountain goat 

 (Oreamnos), the first member of the rupicaprine division of the antelope 

 family to be recorded in North America. Here also occurs an extinct 

 ungulate (Euceratherium) with affinities to the sheep (Ovince) and to Ovibos. 

 As compared with the Port Kennedy Cave or even with the asphaltum 

 deposits, we observe the absence of certain very characteristic early Pleis- 

 tocene forms, especially the saber-tooths (Smilodon) and the giant tapirs. 

 It is of course possible that these absences are due to local causes. The 

 saber-tooths certainly frequented the plains and pampas and survived into 

 late Pleistocene times in North America (Conard Fissure). Similarly, 

 Mylodon, the early Pleistocene sloth, does not occur here, while Megalonyx, 

 a forest and foothill edentate, is abundant. 



It is a very striking fact that the Columbian mammoth (E. columhi) 

 is found here, as well as the forest-dwelling mastodon, this being the earliest 

 record of the mastodon on the Pacific coast. Certainly to be reckoned 



Fig. 208. — Skulls of {A) American extinct bear 

 Arctotherium, (B) recent black bear Ursus america- 

 nus. In the American Museum of Natural History. 



