ICE AGE EST NORTH AMERICAN ARCTIC — FLINT 257 



one of conspicuous evolutionary changes in the animals themselves. 

 On the other hand, cold-climate adaptations did appear in such Pleisto- 

 cene mammals as the woolly mammoth and the musk ox — adaptations 

 that are unknown in the fauna of the preceding Pliocene epoch. 



The only extensive Pleistocene mammal fauna thus far collected in 

 Arctic North America comes from the nonglaciated interior region of 

 Alaska and western Yukon. Here, in frozen muck and silt, has been 

 found a rich collection (Frick, 1930 ; Stock, 1942 ; Quackenbush, 1909) , 

 that includes mammal types both extinct and still living. Among the 

 extinct forms are the short-faced bear (Arctotherium yukonensis), 

 dire wolf {Aenocyon dims) , great cat (Panthera atrox) , ground sloths 

 {Megalonyx and N othrotherium) , camel (Camelops), great bison 

 (Bison crassicornis) , oviboids (Symbos tyrrelli and Bootherium sar- 

 genti) , horse (Equus alaskae) , woolly mammoth (Mammonteus primi- 

 genius), and mastodon (Mammut americanum). Forms still living 

 include lion, peccary, reindeer, moose, bighorn sheep, saiga antelope, 

 Rocky Mountain goat, and the musk ox. The deposits from which 

 the bones are taken have been thought to be of interglacial age, but 

 the assemblage of fossil animals implies such different habitats that 

 both glacial and interglacial faunas are suggested. The ground sloths, 

 peccary, camel, and lion suggest a warmer climate than do the woolly 

 mammoth, musk ox, and reindeer. 7 A more extensive study of the 

 deposits may reveal that they are of more than one Pleistocene date. 



Elephant bones and ivory are widespread in northwestern Alaska, 

 together with fossil horse, musk ox, and beaver (Smith and Mertie, 

 1930, p. 252). Fossil elephant remains, not generically identified, 

 have been found in the Aleutian and Pribilof Islands (G. M. Dawson, 

 1894; Bell, 1898, p. 374) . Teeth ascribed to the Columbian elephant 

 have been found near Edmonton and on an island in James Bay (Bell, 

 1898, pp. 370, 372). Mastodon bones have been collected from the 

 Moose River near Moose Factory on James Bay and from the district 

 west of Lake Winnipegosis (Bell, 1898, pp. 383, 387; Hay, 1923, 

 p. 166) . Fossil musk ox, reindeer, and seal occur in the younger de- 

 posits of Ellesmere Island (Hay, 1923, p. 244) . 



These scattered bits of information hardly provide a firm basis for 

 reconstructing a picture of the arctic plants and animals of the various 

 Pleistocene ages. All we can say with probability is that during the 

 glacial ages the transition zone between tundra and subarctic forest 

 was pushed far south of the Great Lakes region and that during inter- 

 glacial ages it reached somewhat farther north than it does at present. 

 This particular zone is recorded not only by fossil plants but by the 



7 Even the Columbian elephant (Mammuthus columbi) has been reported from Alaska 

 (Bell, 1898, p. 371). If correctly Identified, this form would suggest a warmer-than-glacial 

 climate. 



