Dinosaur Files
how does carbon dating work in dinosaurs?
ok, i know how it works, but how do they know how much c-14 was present within a given dinosaurs body? would different organisms have different c-14 levels?
Public Comments
- It doesn't work with dinosaurs. It only works for things less than 100,000 years old. And I think if you are asking the next bit, you don't really know how it works. Briefly, C14 is an unstable form of carbon with a half life of around 5000 years. It is continually created in the atmosphere. When living things take up carbon, they don't care if it's C12, C13 or C14 so they start off with the same ratio of C14 to the other Cs as the atmosphere. But the C14 slowly breaks down so the ratio changes. So it doesn't matter how much carbon is in a sample, as long as there's enough to determine the ratio. After 50,000 years there's so little C14 left it is difficult to calculate the ratio. Dinosaur bones are not dated directly, they are dated by the strata (rock, soil) they are found in. The rocks are dated using techniques similar to carbon dating, but using elements with a longer half life (eg Beryllium-10 - half life 1.52 million years)
- When anorganism is alive it takes in carbon. Plants take in CO2 to make sugar, animals take in plants or meat which has carbon . There is a certain ratio of C-12 to C-14. After an organism is dead, it no longer takes in any carbon, but the radioactive C-14 continues to break down at a known rate and the ratio changes. It is the ration of C-12 to C-14 found in the bones that is checked and since the half life of the C-14 is known, one can determine how long the organism has been dead. The half life of C-14 is 5730 years. Half life is a time period that it takes half the sample to decay.
