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Scientists often use fossils to evaluate the [[Theory of evolution|theory of evolution]]. They record the [[species]] that they find and compare them to living species in order to create a [[fossil record]] of life of Earth.<ref>Geologic Time: [http://pubs.usgs.gov/gip/geotime/radiometric.html "Radiometric time scale"]</ref><ref>The Virtual [http://www.fossilmuseum.net Fossil Museum"]</ref>

Scientists often use fossils to evaluate the [[Theory of evolution|theory of evolution]]. They record the [[species]] that they find and compare them to living species in order to create a [[fossil record]] of life of Earth.<ref>Geologic Time: [http://pubs.usgs.gov/gip/geotime/radiometric.html "Radiometric time scale"]</ref><ref>The Virtual [http://www.fossilmuseum.net Fossil Museum"]</ref>

Scientists use a process known as [[radiometric dating]] to determine the age of the fossils. Radiometric dating is a technique in which scientists observe the amount of an elemental [[isotope]] within the fossil, then use the rate at which the isotope is presumed to decay to calculate when the organism died. There are a number of different methods, some of which claim to be able to date a specimen that died up to three billion years ago.<ref>Georgia Perimeter College - Historical Geology: [http://www.gpc.edu/~pgore/geology/geo102/radio.htm "Radiometric Dating"]</ref> Since individual radiometric methods are independent they can be cross-check with each other to reduce error.

Scientists use a process known as [[radiometric dating]] to determine the age of the fossils. Radiometric dating is a technique in which scientists observe the amount of an elemental [[isotope]] within the fossil, then use the rate at which the isotope is presumed to decay to calculate when the organism died. There are a number of different methods, some of which claim to be able to date a specimen that died up to three billion years ago.<ref>Georgia Perimeter College - Historical Geology: [http://www.gpc.edu/~pgore/geology/geo102/radio.htm "Radiometric Dating"]</ref> Since individual radiometric methods are independent they can be cross-checked with each other to reduce error.