text: Carbon-14 radioisotopic dating is only good for a range backward about 60,000 years, +/- 5,000 years. That means that it is only good for archaeology, from modern to prehistoric man, and extremely recent paleontology, such as mammoth bones and sabre-toothed cats. For beyond 60,000 years, either Potassium-40 or Uraniums' -238 and -235 are used.