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Published byFelicia Gilbert Modified over 9 years ago
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Scientists have divided geologic history into 4 main parts: Precambrian Time Paleozoic Era Mesozoic Era Cenozoic Era
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4.6 billion – 543 million years ago Life began during this time Atmosphere made of water vapor, CO 2 & N 2 Volcanic eruptions, meteorites, violent storms & intense solar radiation
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Extraterrestrial Life came from outside the planet(i.e. meteor) Creation Divine forces created life Non-Living Matter Spontaneous assembly of molecules
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4 billion years ago - Earth began to cool Water condensed and fell as rain
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Atmosphere of early Earth Hydrogen (H 2 ) Volcanic gas (i.e. methane (CH 4 ), ammonia (NH 3 ), CO, SO 2, N 2, CO 2 ) No free oxygen or ozone
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Energy stimulated chemical reactions = Proteins Nucleic Acids LipidsCarbohydrates UV +
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In the oceans Energy from radiation and storms caused simple chemicals in the oceans & atmosphere to react More complex molecules were made Molecules joined to form cells Prokaryotes: single-celled organisms (without a nucleus) that did not need O 2 to survive
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Cyanobacteria (type of prokaryotic organism) appears over 3 bya Uses sunlight to produce food
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Oxygen gas is released into oceans & air Oxygen molecules react to form Ozone, which absorbs harmful radiation form the sun Now possible for life to exist on Earth’s surface
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VOCs Volatile organic compounds NOx Nitrogen-oxygen compounds
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Eukaryotes appear in the fossil record Organism that contain a nucleus Will evolve into organisms composed of many cells
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“Old life” or “Ancient life” Large fossil record Sponges, coral, squid, clams, trilobites, fish, sharks Reptiles, amphibians, fish, worms, & ferns first appear
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Plants, fungi, & air-breathing animals slowly colonized land Crawling insects first animals to live on land Reptiles & winged insects appear near the end of era LARGEST Mass extinction marks end of era 90% of species extinct Oceans completely changed
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“Middle Life” or “Age of Reptiles” Dinosaurs dominate Earth for 150 million yrs First birds appear Conifers appear Flowering plants appear late in era
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Mass Extinction Dinosaurs Many other plant & animal species Meteorite hit Earth Dust, smoke, fires Temperatures dropped for many years
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“Recent Life” or “Age of Mammals” Many mammals, birds, insects & flowering plants Saber-toothed cats, camels, small horses
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Era we are currently living in Climate changed many times during era Periods of ice ages Animals migrate, adapt, or become extinct
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