Paleontology is the study of fossils. A fossil is any trace of a past life form. Although wood, bones, and shells are the most common types of fossils, under certain conditions soft tissue, tracks, and trails, can be preserved as fossils.
Paleontolgy is divided into several different fields:
There are many explanations for why dinosaurs disappeared (asteroid, lack of H2O, volcano), and paleontologists devote their lives to studying the fossil records to help determine what happened.