scientist who studies fossils. |
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paleontologist |
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information about past life, including the structure of organisms, what they ate, what ate them, in what environment they lived, and the order in which they lived. |
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fossil record |
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term used to refer to a species that has died out. |
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extinct |
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method of determining the age of a fossil by comparing its placement with that of fossils in other layers of rock. |
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relative dating |
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distinctive fossil used to compare the relative ages of fossils. |
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index fossil |
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length of time required for half of the radioactive atoms in a sample to decay. |
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half-life |
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technique in which scientists calculate the age of a sample based on the amount of remaining radioactive isotopes it contains. |
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radioactive dating |
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scale used by paleotologists to represent evolutionary time. |
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geologic time scale |
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one of several subdivisions of the time between the Precambrian and the present. |
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era |
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unit of time into which eras are subdivided. |
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period |
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tiny bubble, formed of large organic molecules, that has some characteristics of a cell. |
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proteinoid microsphere |
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microscopic fossil; ______ of single-celled prokaryotic organisms that resemble modern bacteria have been found in rocks more than 3.5 billion years old. |
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microfossil |
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theory that eukaryotic cells formed from a symbiosis among several different prokaryotic organisms. |
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endosymbiotic theory |
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event in which many types of living things become extinct at the same time. |
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mass extinction |
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large-scale ecolutionary changes that take place over long periods of time. |
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macroevolution |
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process by which a single species or small group of species evolves into several different forms that live in different ways; rapid growth in the diversity of a group of organisms. |
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adaptive radiation |
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process by which unrelated organisms independently evolve similarities when adapting to similar environments. |
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convergent evolution |
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process by which two species evolve in response to changes in each other. |
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coevolution |
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pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change. |
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punctuated equilibrium |
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