The C14 will undergo radioactive decay, and after 5730 years, half of it will be gone. So, if we find such a body, the amount of C14 in it will tell us how long ago it was alive. The method doesn't work on things which didn't get their carbon from the air.
This leaves out aquatic creatures, since their carbon might (for example) come from dissolved carbonate rock.
That causes a dating problem with any animal that eats seafood. After about ten half-lives, there's very little C14 left.
So, anything more than about 50,000 years old probably can't be dated at all.
If you hear of a carbon dating up in the millions of years, you're hearing a confused report. Second, they rarely contain any of the original carbon.
We can't date oil paints, because their oil is "old" carbon from petroleum. And third, it is common to soak new-found fossils in a preservative, such as shellac.
There are many different kinds of radiometric dating and not all conclusions we will reach can be extrapolated to all methods used.
Those isotopes that are not stable decay into daughter nuclei.Ironically, despite its popularity, it is also one of the most misunderstood methods of dating.Many people mistakenly believe carbon dating can be used to date objects that are millions or even billions of years old. Wiens has a Ph D in Physics, with a minor in Geology.His Ph D thesis was on isotope ratios in meteorites, including surface exposure dating.However, when one starts with the Bible and interprets the information received from carbon dating accordingly, one will soon learn that in no way does carbon dating disprove the young earth.