Today, we only know of their existence from the fossil remains. A fossil is a term used to geologists to describe any direct evidence of an organism more than 10,000 years old. This could be part of the original organism such as a bone or imprints such as footprints that are preserved in frozen soil or asphalt lakes.
Paleontology is the study of the fossils of animal and plant life.
Paleontologists are scientists who study these fossils. One type of paleontologist studies the fossil remains of dinosaurs to determine what types of dinosaurs might have existed, what they ate, and how they lived. When a dinosaur fossil is found, a professional paleontologist will carefully and systematically excavate the area for more bones and chart the position of each bone found. They will use their knowledge of geology and dinosaur anatomy to determine where the rest of the bones may be buried. The bones of a single dinosaur skeleton generally lie at the same level of rock.