Geology . igher latitudes, and by its develop-ment on the mountains and plateaus. It might naturally be antici-pated that there would result a sharp struggle for existence, attendedby the destruction of the least adapted forms and the numerical reduc-tion of the whole. Just such a reduction has taken place since, if notthen, and this seems to give some force to the suggestion that the THE PLEISTOCENE OR GLACIAL PERIOD. 501 luxuriance of this great fauna really antedated the congestion attendanton the maximum extension of the ice, and that the extinction of thegiant edentates, which seems to ha
Geology . igher latitudes, and by its develop-ment on the mountains and plateaus. It might naturally be antici-pated that there would result a sharp struggle for existence, attendedby the destruction of the least adapted forms and the numerical reduc-tion of the whole. Just such a reduction has taken place since, if notthen, and this seems to give some force to the suggestion that the THE PLEISTOCENE OR GLACIAL PERIOD. 501 luxuriance of this great fauna really antedated the congestion attendanton the maximum extension of the ice, and that the extinction of thegiant edentates, which seems to have followed their abundance some-what closely, was connected with this extension. If this were true,the fauna would be referred to the Pliocene and the earliest stages ofthe Pleistocene and not to the later or true glacial as to current reference is perhaps warranted by the extremedifficulty of closely correlating widely isolated formations in a transi-tion period like the ]mi Fig, 563.—A club-tailed glyptodont, Doechcurus clavicaudatus, from South America. (After Lydekker.) Australian life.—Owing to the isolation of Australia from theEurasian continent, its organic development followed lines of its vertebrate fauna consisted exclusively of marsupials and mono-tremes. In general, they differed specifically from those now living,and were larger, on the whole. The subsequent dwarfing was pos-sibly due to the less genial climate of the ice age, and is perhaps tobe correlated in time as suggested above. Although the glaciers werebut slightly developed on the Australian mountains, the region doubt-less felt the effects of the wide-spread refrigeration of the higher lati-tudes, and of the aridity which seems to have accompanied some ofits stages. Life in Africa.—Comparatively little is known of the Pleistocenelife of Africa. A moderate climate in the northern portion seems 602 GEOLOGY. to be attested by fluvial accumulations which have
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