Fossils<span> are the preserved remains or traces of animals, plants, and other organisms from the past. ... Paleontologists </span>can<span> determine the age of </span>fossils<span> using methods like radiometric dating and categorize them to determine the </span>evolutionary<span>relationships between organisms.</span>
We can learn what some of now a days species are possibly related to species a long time ago. Fossils can also try to see how far back we can go back into time