General process of radiometric dating
So, some caution might be in order before even long established theories are accepted as the "gospel truth", especially when some of the most famous scientists in the field start to question their own life's work.
Uranium in the environment Although uranium is radioactive, it is not particularly rare.
It is fine to hypothesize that similarities between different creatures are the result of common ancestry, but since such similarities have been and are often conflicting when compared with other features, it might be prudent to hold back a little when making conclusions about any sort of definite taxonomic classification model or even relationship.
The conclusions that are drawn from the evidence are often and have often been very much exaggerated to fit personal beliefs and biases.
The carbon-14 decays with its half-life of 5,700 years, while the amount of carbon-12 remains constant in the sample.
By looking at the ratio of carbon-12 to carbon-14 in the sample and comparing it to the ratio in a living organism, it is possible to determine the age of a formerly living thing fairly precisely. So, if you had a fossil that had 10 percent carbon-14 compared to a living sample, then that fossil would be: t = [ ln (0.10) / (-0.693) ] x 5,700 years t = [ (-2.303) / (-0.693) ] x 5,700 years t = [ 3.323 ] x 5,700 years Because the half-life of carbon-14 is 5,700 years, it is only reliable for dating objects up to about 60,000 years old.