Heredity and Adaptation

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Fossil Noun

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[fos-il]

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Fossil

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The preserved remains, marks, or traces of an ancient organism, often found trapped in layers of rock.

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Body Fossil Noun

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[bod-ee fos-il]

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Body Fossil

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A type of fossil formed from the preserved hard parts of an organism, such as its bones, shells, or teeth.

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Trace Fossil Noun

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[trays fos-il]

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Trace Fossil

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A type of fossil that preserves evidence of an organism's activities, such as tracks, burrows, or impressions in rock.

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Sedimentary Rock Noun

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[sed-uh-men-tuh-ree rok]

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Sedimentary Rock

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Rock formed from compressed layers of sediment like sand or mud, which often contains and preserves fossils.

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Paleontologist Noun

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[pey-lee-uhn-tol-uh-jist]

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Paleontologist

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A scientist who studies fossils to understand the history of life on Earth and the evolution of organisms.

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Tetrapod Noun

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[te-truh-pod]

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Tetrapod

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A vertebrate animal that has four limbs, or is descended from an ancestor with four limbs.

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Principle of Superposition Noun

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[prin-suh-puhl of soo-per-puh-zish-uhn]

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Principle of Superposition

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The scientific rule that in undisturbed sedimentary rock layers, the lower layers are older than the layers above them.

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Relative Dating Noun

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[rel-uh-tiv dey-ting]

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Relative Dating

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The method of determining the comparative age of rock layers or fossils without finding their exact age in years.

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Absolute Dating Noun

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[ab-suh-loot dey-ting]

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Absolute Dating

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The method of determining the precise age of a rock or fossil in years, often using radioactive decay.

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Isotope Noun

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[ahy-suh-tohp]

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Isotope

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One of several forms of a chemical element, where each form has a different number of neutrons in the nucleus.