Paleontology << `pay` lee on TOL uh jee >> is the study of animals, plants, and other organisms that lived in prehistoric times (more than 5,500 years ago). Fossil remains of organisms occur in layers of sedimentary rock, which forms from the buildup of dirt, rock fragments, sand, and other sediments. The organisms were alive when the rocks were being formed. They were buried and preserved as fossils as the layers of rock piled up.
Paleontologists study fossils to learn what kind of life existed at various times in Earth’s history. They also examine how once-living organisms relate to one another and to those alive today. The oldest known fossils are bacteria that lived about 3 1/2 billion years ago. The fossil record shows that living things gradually formed and developed over time through the process of evolution.
Paleontology is important in the study of geology. The age of rocks may be determined by the fossils in them. Fossils also tell whether rocks were formed under the ocean or on land. Most rocks that contain marine shell fossils were formed under the ocean. Most rocks that contain land animal and land plant fossils were formed on land or in streams and lakes. The knowledge of where rocks were formed helps scientists called paleogeographers map the world as it was millions of years ago. Paleontology also aids in the location of oil, which is often found in rocks that contain certain fossils.
There are three main branches of paleontology: (1) invertebrate paleontology, (2) vertebrate paleontology, and (3) paleobotany. Invertebrate paleontology deals with fossil invertebrates (animals without backbones), such as mollusks and corals. Vertebrate paleontology is concerned with extinct fishes, amphibians, reptiles, birds, and mammals. Paleobotany is the study of fossil plants.
