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Plants and Animals in Nature
Plants and animals in nature

There are approximately 10 to 50 million species of living organisms on Earth. Perhaps 2 million of them have been scientifically identified, described, and named. Biological diversity developed over millions of years as a consequence of physical geographic and environmental processes. More than 200 million years ago, tectonic movements began to separate and realign landmasses with respect to each other and in relation to the equator and poles. The Northern Hemisphere has most of the land, with an ocean at the pole. The Southern Hemisphere is mostly ocean but with a continental landmass, Antarctica, at the pole. Various geographic barriers also isolated populations of living organisms. In the Americas, the major mountain ranges are oriented from ...

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