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Maximum age limit radiocarbon dating fossils

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Scientific papers and news reports about new fossils so regularly come with estimates of age that it’s easy forget how hard-won such data can be.

I asked John Hawks, a biologist at the University of Wisconsin and one of the heads of the Rising Star expedition, to talk me through the various available methods—and why they have been difficult to apply to the latest finds.

The Oxalic acid standard was made from a crop of 1955 sugar beet. The isotopic ratio of HOx I is -19.3 per mille with respect to (wrt) the PBD standard belemnite (Mann, 1983). T designation SRM 4990 C) was made from a crop of 1977 French beet molasses.

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It hinges upon the presence of carbon-14, a radioactive isotope of carbon that accumulates in the bodies of animals throughout our lives, and gradually decays after we die.

Plants and animals assimilate carbon 14 from carbon dioxide throughout their lifetimes.

When they die, they stop exchanging carbon with the biosphere and their carbon 14 content then starts to decrease at a rate determined by the law of radioactive decay.

Carbon dating has a certain margin of error, usually depending on the age and material of the sample used.

Carbon-14 has a half-life of about 5730 years, and therefore it is used to date biological samples up to about 60,000 years in the past.