Fossil

Contents

Key Stage 2

Meaning

The fossil of an animal's skeleton.

A fossil is a piece of a dead creature that has turned into rock over millions of years.

Singular Noun: Fossil

Plural Noun: Fossils

Adjective: Fossilised

About Fossils

A fossil begins as a creature that dies and falls into mud or sand.

Over millions of years the mud or sand turns into a rock with the creature trapped inside.

The creature is replaced by minerals leaving a rock that is the same shape as the creature.

In animals it is usually only the bone that becomes a fossil.

Evidence of Evolution

Fossils show us many creatures that do not exist anymore.

The Tyrannosaurus Rex is a Dinosaur that became extinct 66 million years ago.	The Giant Sloth lived in North America and became extinct 10,000 years ago at the end of the last Ice Age.
The Dimetrodon became extinct long before the Dinosaurs even existed.	The Moa has only been extinct for about 500 years.

Fossils appear slightly different as you dig into older rocks. When you dig far enough the oldest fossils look very different to the modern creatures.

Modern horse fossils are only found in rocks younger than 5 million years old. They are around 6 feet tall, have hooves and a large nose.	This fossil comes from 7 million year old rocks. It is shorter and has a smaller nose than modern horses. You do not find modern horse fossils in rocks this age.
This fossil comes from 12 million year old rocks. It has a small hoof but toes next to the hooves. It is also much shorter than modern horses.	This fossil comes from 34 million year old rocks. This ancestor of modern horses had toes without a hoof and was the size of a dog.

Key Stage 3

Meaning

Fossils are the remains of a dead organisms that became trapped in sedimentary rock and turned into rock themselves over millions of years.

About Fossils

Fossils are only found in sedimentary rocks but not in igneous rocks.

It is very rare to find a complete fossil of a large animal. Most fossils of animals actually have the bones from lost of different members of the same species.