Imagine your sample contained 20% of the carbon-14 found in a living plant leaf.
Then, First, carbon-14 cannot be used to date biological artifacts of organisms that did not get thier carbon dioxide from the air.
This technique is not restricted to bones; it can also be used on cloth, wood and plant fibers. The short half-life of carbon-14 means its cannot be used to date extremely old fossils.
Carbon-14 dating has been used successfully on the Dead Sea Scrolls, Minoan ruins and tombs of the pharohs among other things. Levels of carbon-14 become difficult to measure and compare after about 50,000 years (between 8 and 9 half lives; where 1% of the original carbon-14 remains undecayed).
The ratio of carbon-14 to carbon-12 in the atmosphere and on earth is nearly constant, although there has been some change in carbon-14 concentration over the last 10,000 years.
Carbon-14 formed in the atmosphere can combine with oxygen to form carbon dioxide (CO2).
Also, many fossils are contaminated with carbon from the environment during collection or preservation proceedures.
When scientists first began to compare carbon dating data to data from tree rings, they found carbon dating provided "too-young" estimates of artifact age.
Carbon dating cannot be used on most fossils, not only because they are almost always too old, but also because they rarely contain the original carbon of the organism.Scientists now realize that production of carbon-14 has not been constant over the last 10,000 years, but has changed as the radiation from the sun has changed.Carbon dates reported in the 1950s and 1960s should be questioned, because those studies were conducted before carbon dating was calibrated by comparision with other dating methods.Carbon dating is used to determine the age of biological artifacts up to 50,000 years old.This technique is widely used on recent artifacts, but teachers should note that this technique will not work on older fossils (like those of the dinosaurs which are over 65 million years old).Nitrogen normally occurs in a seven proton, seven nuetron, nitrogen-14 state.When it collides with an energetic neutron it becomes carbon-14, with six protons and eight neutrons and gives off a hydrogen atom with one proton and zero neutrons. Carbon-14 is an isotope of carbon, which exists only is small amounts in the environment (1 in one trillion carbon atoms is carbon-14).Although the half-life of carbon-14 makes it unreliable for dating fossils over about 50,000 years old, there are other isotopes scientists use to date older artifacts.These isotopes have longer half-lives and so are found in greater abundance in older fossils.By comparing the ratio of carbon-14 to carbon-12 in an artifact to the ratio of carbon-14 to carbon-12 in living organisms scientists can determine the age of an artifact.If you wanted to date a fossil, first you would determine the percent carbon-14 it contained compared to a living sample.