Fossils are animal or plant prints or body parts that have been left and have formed into a rock.. Paleontologists dig for fossils and record where they find them and try to figure out what type of animal or plant left them. What Is The Fossil Record The fossil record is fossils that have been found and scientists know what left them. They have been recorded so Paleontologists can study the kind of life back then. The fossils have been preserved usually in some sort of rock. How Are They Used As Evidence These fossils are used as evidence because scientists can now study the features that the creature has. Sometimes they can see if this creature has many organs and cells to see how old they really are or see the roots on a plant and see how deep they are. This shows how old this plant is because early plants had short roots because they were low lying plants. It plays a big role in discovering how old the Earth is.