Rates of radiocarbon production vary through time, in a quasi-periodic manner.
This technique is widely used on recent artifacts, but educators and students alike should note that this technique will not work on older fossils (like those of the dinosaurs alleged to be millions of years old).
This technique is not restricted to bones; it can also be used on cloth, wood and plant fibers.
In the figure right, the production of radio-active carbon is demonstrated.
Here, 7 protons and 7 neutrons (N) plus one neutron form an isotope of carbon, with 8 neutrons and 6 protons.
Also, many fossils are contaminated with carbon from the environment during collection or preservation procedures.