Paleontologists study the history of life on Earth as shown in the fossil record. Fossils are the traces of organisms that lived in the past and are preserved in Earth's crust. Paleontology involves the identification and naming of fossil species and organisms and the determination of the environment in which they lived. Paleontology is considered a subcategory of geology. It is a very broad science that uses biology, geology, chemistry, and physics. There are many subdivisions in the field of paleontology, including:

• vertebrate paleontology, the study of fossils of animals with backbones;
• invertebrate paleontology, the study of fossils of animals without backbones;
• micropaleontology, the study of fossils of single-celled organisms;
• paleobotany, the study of plant fossils;
• paleoecology, the study of ancient environments;
• biostratigraphy, the study of the fossils in rock layers from different areas to determine their relative ages.

As can be seen by this list, paleontology is...