CREATION BY EVOLUTION
as sand millions of years ago, tells of ages when some of the fishes were stranded in pools that at times dried up. Under these circumstances some of them passed from gill-breathing to lung-breathing animals and acquired paddle-like legs suitable for scrambling about on land.
Thus arose the first backboned animals that spent part of their life on land and part in water—the amphibians, which are now represented by the newts, salamanders, frogs, and toads. Then, through more tribulation of drought and desert in the Permian epoch, there came the equally cold-blooded reptiles—lizards, crocodiles, alligators—animals capable of living all their life on land. They found conditions so easy that they literally swarmed over all lands and even invaded the air as flyers and the sea as swimmers. They increased immensely in bodily bulk until some of their latest representatives in the Cretaceous period (the period of the Chalk) were the biggest masses of flesh that ever lived on land.
A few of the more progressive of these reptiles rather early began to show signs of becoming something better, and by the time the giants of the group were worn out, the progressives had become warm-blooded animals, with an improving brain and very active legs. These were the mammals, quadrupeds which soon began to suckle their young and care for them in their youth. At the beginning of the Tertiary period they took the place of the giant reptiles, which had disappeared. Birds also took possession of the air.
During the Tertiary period the mammals occupied every sphere of life on the land, and as they became more completely adapted to their surroundings their brains grew relatively larger and more useful. As the flesh-eaters advanced in power of jaw and in cunning, and as the vegetable-feeders
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