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Period: to
Precambrian Time
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First crustal rocks form.
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Earth's surface is cool enough for liquid water
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First known unicellular life appears
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Earth'satmosphere starts to become oxygen rich
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First known multicellular life appears
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First fungi appears
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First sheltered organisms, such as arthropods and mollusks, appear
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Period: to
Paleozoic Era
the geologic era that followed Precambrian time and that lasted from 542 million to 251 million years ago. -
First possible Vertebrates appear
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Modern, oxygen-rich atmosphere has formed
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First land plants appear
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First amphilbians appear
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First reptiles appear
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Formation of pangea is complete
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Permain mass extinction results from major enviroment changes
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Period: to
The Mesozoic Era
the geologic era that lasted from 251 million to 65.5 million years ago; also called the Age of Reptiles -
Pangaea begins to break apart
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First mammals appear
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First primitive birds appear
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First flowering plants (angiosperms) appear
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First modern birds appear
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The last disnosaurs become exinict Catastrophic meteorite impact occurs
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Period: to
The Cenozoic Era
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Most modern mammal familes, including whales, carnivores, hooved animals, and primates have appeared
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First grasses appear
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India colides with Asia, and Anartica drifts over south pole
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First hominids (early human ancestors) appear
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Modern Ice Age appears
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Modern humans appear
