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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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