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Radiometric dating

The estimation of the age of an object by measuring its content of certain radioactive isotopes


Charged particles (radiation)


The time required for half of a sample of radioactive substance to disintegrate by radioactive decay or by natural processes


Short chains of amino acids can gather into tiny water droplets


The preserved or mineralized remains (bone, tooth, or shell) or imprint of an organism that lived long ago


Photosynthetic prokaryotes


Prokaryotes that contain a chemical called peptidoglycan in their cell walls


Prokaryotes that lack peptidoglycan in their cell walls and have unique lipids in their cell membranes


The theory that mitochondria are descendants of symbiotic, aerobic (oxygen-requiring) eubacteria and chloroplasts are descendents of symbiotic, photosynthetic eubacteria


Make up a large, varied group that includes both multicellular and unicellular organisms


The death of all members of a species

Mass extinction

And episode during which large numbers of species become extinct


Symbiotic associations between fungi and the roots of plants


A kind of animal with a hard outer skeleton, a segmented body, and paired, jointed limbs

Continental drift

The movement of Earth's land masses over Earth's surface through geologic time

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