AMS dating lab Beta Analytic is inviting members of the Society of American Archaeology (SAA) to join the raffle at Booth #300 during the 84th SAA Annual Meeting to be held at the Albuquerque Convention Center in Albuquerque, New Mexico, from April 10-14, 2019.
If the ratio is a quarter of what it should be (one in every four trillion) we can assume the creature has been dead for 11,460 year (two half-lives).
After about 10 half-lives, the amount of radiocarbon left becomes too miniscule to measure and so this technique isn't useful for dating specimens which died more than 60,000 years ago.
For two important reasons, this does not mean that the sample comes from 3619 BC: Many types of tree reliably lay down one tree ring every year.
The wood in these rings once laid down remains unchanged during the life of the tree.
Volcanoes spew out CO which could just as effectively decrease the ratio.
Specimens which lived and died during a period of intense volcanism would appear older than they really are if they were dated using this technique.
We must also assume that the ratio of C-12 to C-14 in the atmosphere has remained constant throughout the unobservable past (so we can know what the ratio was at the time of the specimen's death).
And yet we know that "radiocarbon is forming 28-37% faster than it is decaying," which means it hasn't yet reached equilibrium, which means the ratio is higher today than it was in the unobservable past.
The period of time that it takes for half of a sample to decay is called a "half-life."Radiocarbon oxidizes (that is, it combines with oxygen) and enters the biosphere through natural processes like breathing and eating.
Plants and animals naturally incorporate both the abundant C-12 isotope and the much rarer radiocarbon isotope into their tissues in about the same proportions as the two occur in the atmosphere during their lifetimes.
C-12 is by far the most common isotope, while only about one in a trillion carbon atoms is C-14.