A Story Outline of Evolutio 



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the amphibians crawled out on land and began to breathe 

 their oxygen from the air, a new adaptation was necessary 

 and Evolution stepped in and created a new or third heart 

 chamber which gave to them greater capacity for purifying 

 the blood and becoming more active in their new environ- 

 ment. The circulatory system of the fis;hes is much more 

 complex than that of the invertebrate animals and the cir- 

 culatory system of the amphibians is much more complex 

 than that of the fishes. In like manner all the other body 

 organs were changed to meet the new environment surround- 

 ing them. 



The amphibians were the first to leave the water and to 

 take up their abode on land. Here they literally left their 

 "footprints on the sands of time." Their tracks are found 

 imbedded in the sandstones as early as the Devonian period. 

 They became armored giants in the Carboniferous period 

 attaining a height and length of several feet. The early 

 amphibians lived in a period of world-wide uniformity of 

 climate with a warm moist atmosphere with less light and 

 heat coming from the sun. At this time the air was perhaps, 

 not yet sufficiently purified for the life of man but Evolution 

 was preparing the way for the higher life that was to follow. 



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