Second, Radiocarbon Dating has been used to date things like Dinosaurs and Mammoths, animals that are extinct. See the problem? Without the living host, WE HAVE NO IDEA HOW MANY CARBONS WERE IN THE ANIMAL ORIGINALLY! If we had a live Tyrannosaurus that had X carbon atoms in it, we could then begin tracing the half-life of the carbon we find in fossils beneath the ground. But we don't have a live Tyrannosaurus, so carbon doesn't--as of yet--help us with dating fossils of animals that have gone extinct.