Fossils are what is left of plants and animals. They are from long ago. Fossils are found in rock.

Bones can become fossils. Shells and leaves can become fossils too. A footprint can be a fossil.

There are two kinds of fossils. They are body fossils and trace fossils. Feather or skin prints can be trace fossils too.

Most animals and plants that die rot away. They do not become fossils.

A dead animal or plant can become a fossil. It has to be covered up fast. Mud, sand or silt often bury it before it rots.

Bones, teeth and shells are hard parts. Hard parts become fossils more often than soft ones.

Water full of minerals seeps into buried bones and teeth. It slowly turns them to stone.

Amber is tree sap. It turned hard and old. Amber can hold tiny animals. Some are ants and flies.

We find the fossils of dinosaurs. So we know dinosaurs lived. Fossils tell us which plants and animals lived long ago.

Tiktaalik was a fish. It had a flat head like a crocodile.

Words to know

• silt: fine mud
• minerals: rock bits
• amber: old tree sap