A paleontologist is a scientist who studies fossils. If your basement is filled with fossils found while out on hikes, then you're an amateur paleontologist.
Paleontology breaks down to the Greek for "ancient" (paleo), "being" (onto-), and "study" (-logy). A paleontologist tries to figure out how things were in ancient times by studying their remains in fossil traces. If you are obsessed with all things related to dinosaurs, becoming a paleontologist might make sense for you.