Radiocarbon dating of fossils
The C14 will undergo radioactive decay, and after 5730 years, half of it will be gone. So, if we find such a body, the amount of C14 in it will tell us how long ago it was alive. The method doesn't work on things which didn't get their carbon from the air.
This leaves out aquatic creatures, since their carbon might (for example) come from dissolved carbonate rock.
Researchers have found a reason for the puzzling survival of soft tissue and collagen in dinosaur bones - the bones are younger than anyone ever guessed.
Carbon-14 (C-14) dating of multiple samples of bone from 8 dinosaurs found in Texas, Alaska, Colorado, and Montana revealed that they are only 22,000 to 39,000 years old.
The stable form of carbon is carbon 12 and the radioactive isotope carbon 14 decays over time into nitrogen 14 and other particles.
Carbon-dating Carbon dating, like other radiometric dating methods, requires certain assumptions that cannot be scientifically proved.
These include the starting conditions, the constancy of the rate of decay, and that no material has left or entered the sample.
Carbon is naturally in all living organisms and is replenished in the tissues by eating other organisms or by breathing air that contains carbon.
At any particular time all living organisms have approximately the same ratio of carbon 12 to carbon 14 in their tissues.
Members of the Paleochronology group presented their findings at the 2012 Western Pacific Geophysics Meeting in Singapore, August 13-17, a conference of the American Geophysical Union (AGU) and the Asia Oceania Geosciences Society (AOGS).