Whenever possible, researchers use one or more absolute dating methods, which provide an age for the actual fossil or artifact. By Gemma Tarlach Wednesday, June 01, Afterward, the amount of the radioactive isotope carbon in their remains decreases.
Since animal species change over time, the fauna can be arranged from younger to older. A submethod within biostratigraphy is faunal association: Paleontologists still commonly use biostratigraphy to date fossils, often in combination with paleomagnetism and tephrochronology. Think of it as ordering rather than dating. Measuring carbon in bones or a piece of wood provides an accurate date, but only within a limited range. Archaeologists also frequently use TL to date ceramics, which are also exposed to high temperatures during manufacture.