Fossils are what is left of plants and animals from long ago. Fossils are found in rock. There are two kinds of fossils: body fossils and trace fossils. Bones can become fossils. Shells and leaves can become fossils too. Footprints and feather or skin prints can be trace fossils. Scientists who study fossils are called paleontologists. Paleontology is the study of the history of life on Earth.

Most animals and plants that die rot away and do not become fossils. To become a fossil, a dead animal or plant has to be covered up fast. Hard parts such as bones, teeth and shells become fossils more often than soft parts. Water full of minerals seeps into buried bones and teeth and slowly turns them to stone. Layers of mud and sand pile up and slowly turn into rock. Making a fossil takes a very long time, often thousands to millions of years.

Tracks are the marks that an animal leaves as it moves. Trace fossils, such as tracks, tell us about what an animal did. Tracks tell how long a dinosaur's stride was, and the spacing of the prints shows it.

Relative dating tells which fossil is older and which is younger, but not the age in years. Scientists can use radioactive atoms in rock like a clock to work out how old the rock is.

Amber keeps small bodies in fine detail, so it tells scientists a lot about the anatomy of ancient insects. Stromatolites are fossils made by mats of tiny living things called cyanobacteria.

Mary Anning found the first complete skeleton of a Plesiosaurus, an ancient sea reptile. Oviraptor was named "egg snatcher" because people thought it stole eggs, but the eggs it was found with were its own.

As of November 2026, in national parks fossils may not be collected, and on other public land fossils taken for personal use may not be sold.

Fossils tell us which plants and animals lived long ago. Fossils help show how living things changed over time. Fossils can show what the climate was like long ago. Fossils are our best evidence for the history of life on Earth.

Words to know

• paleontologists: fossil scientists
• minerals: rock materials
• stride: one long step
• radioactive: giving off energy
• amber: hard old sap