Archaeologists and scientists use absolute dating methods on samples ranging from prehistoric fossils to artifacts from relatively recent history.
Chronometric techniques include radiometric dating and radio-carbon dating, which both determine the age of materials through the decay of their radioactive elements; dendrochronology, which dates events and environmental conditions by studying tree growth rings; fluorine testing, which dates bones by calculating their fluorine content; pollen analysis, which identifies the number and type of pollen in a sample to place it in the correct historical period; and thermoluminescence, which dates ceramic materials by measuring their stored energy.
The process of finding out the actual order of the events that happened in the past become known as absolute dating.
The process of finding out the similar order of the events that took place in the past become known as relative dating.
Using relative dating the fossil is compared to something for which an age is already known.
For example if you have a fossil trilobite and it was found in the Wheeler Formation.
Relatively young deposits can be sometimes dated using tree rings, varved-lake sediments, coral growth patterns, and other methods.