Why can’t the age of fossils be accurately determined, like to the exact year?
In order to get the right year for a fossil in general, you have to be extremely accurate. For example, if you were trying to date something that was a million years old (not long in geological terms) to tht accuracy, you would have the accuracy of one part in a million. That is extremely accurate. You need an extremely well-controlled experiment and lots of data to get that level of accuracy. This is not possible with fossils that have been through millions or hundreds of millions of years of uncertain chemical and physical changes. For the fossils of the Cambrian, the accuracy would be one part in 500 million. The decay constants of radioactive elements is not known to that level of accuracy. Furthermore, for fossils of this age, it is likely that none of the original atoms remain in the fossil, so dating the fossil itself must be done by more indirect means.
