The most widely known form of radiometric dating is carbon-14 dating.
This is what archaeologists use to determine the age of human-made artifacts. The half-life of carbon-14 is only 5,730 years, so carbon-14 dating is only effective on samples that are less than 50,000 years old.
The age of the fossil must be determined so it can be compared to other fossil species from the same time period.
Understanding the ages of related fossil species helps scientists piece together the evolutionary history of a group of organisms.
Dinosaur bones, on the other hand, are millions of years old -- some fossils are billions of years old.
Mountains have been built and eroded, continents and oceans have moved great distances, and the Earth has fluctuated from being extremely cold and almost completely covered with ice to being very warm and ice-free.Sedimentary rocks are rarely useful for dating because they are made up of bits of older rocks.Uranium is present in many different rocks and minerals, usually in the form of uranium-238.The second method is called absolute dating and is done by analysing the amount of radioactive decay in the minerals of the rocks.Scientists find out the age of a dinosaur fossil by dating not only the rocks in which it lies, but those below and above it.