Fossils are the remains of once living animals or plants. People have been finding fossils in rocks for thousands of years, but until quite recently they didn't understand what they were.
Today we recognise that the fossils we find in rocks represent the ancestors of the animals and plants that are alive today.
What can fossils tell us?
Fossils give us information about how animals and plants lived in the past.
Once people began to recognise that some fossils looked like living animals and plants, they gradually began to understand what they were. They realised they were actually the ancestors of today's plants and animals.
Some fossils are easy to identify and look like plants and animals alive today.
While we can easily recognise and identify some fossils, many fossils represent animals that no longer exist on Earth. We only know about extinct groups like dinosaurs, ammonites and trilobites through fossils.
Some animals and plant are only known to us as fossils.
By studying the fossil record we can tell how long life has existed on Earth, and how different plants and animals are related to each other. Often we can work out how and where they lived, and use this information to find out about ancient environments.
An animal dies, and its skeleton settles on the sea floor and is buried by sediment.
An animal dies and its body sinks to the sea floor. The soft parts of the animal rot away, leaving only its skeleton. The skeleton is buried by sediment (like mud or sand) falling from the ocean above. The sea floor is an ideal place for fossilisation, which explains why many fossils are from animals that lived in the sea. Land animals may die and be swept out to sea to be buried in the same way.
The sediment surrounding the skeleton thickens and begins to turn to stone.
The skeleton continues to be buried as sediment is added to the surface of the sea floor. As...