Fossils tell us about animals that lived on earth in prehistoric times. This is a pterodactylus. Getty Images

Fossils tell us about animals that lived on earth in prehistoric times. This is a pterodactylus. Getty Images

What are fossils?

Fossils are the remains of a dead animal or plant that has been preserved in rock. They are clues to a time long ago, before there was a recorded history.

Sometimes the fossil is just an imprint such as a footprint, or even an animal's dung.

 Fossils are generally found in rocks that were once under water.

An animal or plant died and was first covered by mud, and the soft parts decayed, leaving hard material (like bones or shell). Over thousands of years, many layers of soil or mud built up and were squeezed together. Water containing minerals seeped through the layers and changed the plant or animal into rock. Then over more hundreds of years, erosion has worn away the rock and people discover the fossils as they become exposed.  

Sometimes a fossil can be similar to an animal alive today, and the differences can tell scientists how that animal has evolved.

Fossilised insects in amber. ©Getty Images

Fossilised insects in amber. ©Getty Images

Fallen trees become fossilised in the same way. Fossilised wood is called petrified wood.  

Tree sap that has oozed from a tree can be fossilised into a stone called amber. Sometimes small insects trapped in the sticky sap are inside the amber. This can also show scientists what the first insects looked like.

Palaeontologists

©Getty Images Palaeontologists

©Getty Images Palaeontologists

Scientists called palaeontologists  (say pale-ee-en-toll-uh-jists) learn about dinosaurs and about what the world was like in prehistoric times by studying fossils.

 Prehistory refers to a time long before recorded history. There were no people in the time of the dinosaurs, so there was no human recording of what life was like.  A study of fossils has given us that information.

Sand around a fossil bone is carefully brushed away ©Getty Images

Sand around a fossil bone is carefully brushed away ©Getty Images

Fossil remains of dinosaurs have been found on all continents except Antarctica. Palaeontologists are rather like detectives or puzzle solvers, working out answers from small clues.  They piece together small fossils and work out what a prehistoric animal or plant might have been like, using many clues.

Bones are often scattered, and must be gathered and carefully moved to a work area before the work of putting together a skeleton can begin.  Fossils are gently freed from the surrounding rock. Dirt is scraped away, and then brushes are used to expose the fossil. It is slow, careful work.  

Animal dung (poo) gets fossilised too, and that can tell scientists how big the animal was and what it ate.

Fossilised animal poo is callled coprolite. ©Getty Images

Fossilised animal poo is callled coprolite. ©Getty Images

Fossilised animal teeth also tell us what an animal ate: carnivores and herbivores have different teeth, and grooves along the teeth tell scientists whether the animal tore at its prey or swallowed it whole. Some plesiosaurs had cone-shaped teeth, which were ideal for crushing hard shells of sea creatures like ammonites.

A fossil ammonite ©Getty Images

A fossil ammonite ©Getty Images

Claws tell palaeontologists something about how a carnivore caught its prey.

Giant Jigsaws!

When paleantologists have gathered dinosaur bones, it is rather like a giant jigsaw as they slowly piece them together to form a complete skeleton. From this they can begin to solve other questions such as what the animal ate, how it moved and so on, based on the evidence they have discovered.  Smaller fossils can also be in pieces that must be put together.  

Triceratops skeleton: a giant 3D jigsaw puzzle for scientists ©Getty Images

Triceratops skeleton: a giant 3D jigsaw puzzle for scientists ©Getty Images

Fossilised trilobites ©Getty Images

Fossilised trilobites ©Getty Images

Go here to find out more about fossils and how they form:

http://www.oum.ox.ac.uk/thezone/fossils/intro/form.htm

Go here to find out about Australian sites where dinosaur fossils have been found:

http://www.alphalink.com.au/~dannj/sites.htm

 

 

Read the kidcyber pages:

Dinosaur Egg Fossils

Watch a palaeontologist using fossil clues to work out how dinosaurs made nests

Explore educational games on prehistoric animals at NeoK12  

Watch another video, this one about the formation of fossils