The Three Main Types of Fossils

Fossils are reliable for the study of life on planet Earth.
••• Steffen Foerster/iStock/Getty Images

Fossils have been used throughout history to document and date the different species of animals that have existed on Earth. From dinosaurs to neanderthals, fossils are integral to the accurate dating of life's time line on the planet. According to "Enchanted Learning," archaeologists use three main types of fossil: the true form fossil, trace fossil and mold fossil; a fourth type is the cast fossil. Fossilization can take millions of years to occur.

True Form Fossils

A true form fossil of a plant.
••• Emmanuel Lacoste/iStock/Getty Images

These fossils are made of an actual plant or animal. The hard parts of the body like the bones or stems were trapped in rock and effectively preserved. The soft parts of the body like the skin and muscle usually decompose before fossilization can occur.

Trace Fossils

Footprints are one example of trace fossils.
••• Jultud/iStock/Getty Images

According to "Enchanted Learning," these fossils can record the behaviors and movements of animals. Footprints, nests and fecal matter are all examples that reveal information about the animal's lifestyle.

Mold Fossils

A mold fossil.
••• Ralf Hettler/iStock/Getty Images

According to "Exploring Earth," mold fossils are hollow impressions left by a plant or animal. The surrounding mud and sediment hardens around the dead organism and only an imprint of it remains after decomposition.

Cast Fossils

Scientist working with a cast fossil.
••• David McNew/Getty Images News/Getty Images

A cast fossil is a byproduct of a mold fossil. According to "Exploring Earth," when sediment fills in a hollow mold fossil, a cast fossil forms. The cast is a natural occurring replica of the actual organism.

Related Articles

What Is a Frozen Fossil?
Ideas for a Fossil Science Fair Project
The Four Types of Fossils
Fossil Facts for Children
Five Different Types of Fossils
What Is a Body Fossil?
Types of Fossils & How They Are Formed
What Different Types of Fossils Are There?
Kinds of Fossil Rocks
What Information Can Scientists Get From Fossils?
What Is a Frozen Fossil?
Mold & Cast Fossils
Why Do Scientists Study Fossils?
Ideas for a Fossil Science Fair Project
What Is an Imprint Fossil?
Definition of a Preserved Fossil
Fossils That Are Most Useful for Correlation
What Is a Preserved-Remains Fossil and How Are They...
Types of Fossil Preservation
Types of Plant Fossils