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17 Cards in this Set
- Front
- Back
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Cambrian Explosion
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when a great number of different organisms evolved
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carbon-14
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used by geologists often to date materials that lived up to about 50,000 years
ago |
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evolution
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process when all the different kinds of living things have changed over long
periods of time |
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fossil
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preserved remains or traces of living things
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half-life
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the time it takes for half of the radioactive atoms to decay in a radioactive
element |
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intrusion
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magma that forces its way into rocks and hardens
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paleontologist
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a scientist who studies fossils
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periods
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what the Geologic Time Scale eras are divided into
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petrified fossil
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when minerals replace all or part of an organism
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radioactive dating
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scientists use to determine the absolute ages of rocks
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reptiles
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evolved from amphibians
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sedimentary
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the level of rock where fossils are most always found
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vertebrate
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an animal with a backbone
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invertebrate
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an animal without a backbone
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Precambrian Time
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when earliest forms of life appeared
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Paleozoic Era
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when plants and animals first reached land
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Mesozoic Era
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known as the “Age of the Reptiles”
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