Carbon dating can only be used for things less than about 50,000 years old. And it has to be living once. ALL fossils and fossil fuels can be carbon dated.
Which is why they don't use carbon-14 dating for dinosaur fossils. They use uranium-238, uranium-235, and potassium-40 dating, which have half lives in the millions of years, unlike carbon-14, which is useful only for dating man made objects.
