Paleontology is the study of ancient life.  Paleontologists use fossils, the remains of animals and plants preserved in rocks, to interperet the past.  There are several subdiciplines within paleontology:
 

• Inveretbrate Paleontology deals with fossils of animals without backbones such as clams, snails and starfish
• Vertebrate Paleontology deals with fossils of animals with backbones such as fish, amphibians, reptiles, mammals and birds.
• Micropaleontology deals with microscopic lifeforms.
• Paleobotany deals fossil plants.
• Ichnology deals the study of fossil footprints, tracks, trails and burrows.
• Biostratigraphy deals with using fossils to correlate time.