Fossil Facts: Lesson for Kids

Instructor: Sarah Caughron

Sarah has a master's degree in Applied Anthropology/Archaeology and has worked in formal and informal education since 2006.

If you've ever visited a natural history museum, you've probably observed fossils of dinosaurs, mammoths, plants, and insects. While these are bones, they're probably not the type that would interest your dog! In this lesson, you will learn what a fossil is, how a fossil is formed, and what type of scientist studies fossils.

What is a Fossil?

Fossils are the preserved remains of living organisms including insects, animals, and plants. Fossils can be as old as hundreds of millions of years old or as young as 10,000 years old. Scientists called paleontologists study fossils and create stories about the past by recreating environmental conditions through discovering ancient plants and animals.

Fossilized Reptile
Fossilized Reptile

Types of Fossils

There are typically two major types of fossils: trace fossils and body fossils. Trace fossils refer to fossils representing a trace of an organism. This includes footprints, egg shells, nests, and skin impressions. For example, one of the ways we know that many dinosaurs were covered in scales is by discovering fossilized skin impressions. Even poop can become fossilized! Scientifically, fossilized fecal remains are called coprolites and offer insight about past diets and subsistence.

Body fossils are more commonly what we think of when we think of fossils. These are the preserved remains of a body part of an animal as well as plant remains. Included in this category are skeletal remains, plant remains, like leaf impressions, and fossilized sea shells. When a tree becomes a fossil, it is called petrified wood.

Petrified Wood
Petrified Wood

How are Fossils Made?

Most fossils are formed by the process of permineralization. For this process to happen, an animal must die and be buried quickly by sediments, or tiny particles of sand, dirt, or volcanic ash. Next, groundwater fills up all of the empty space in the body as it decomposes, or breaks down. Since water is a solvent, it slowly dissolves all the organic material like skin, organs, and hair, and the minerals in the water replace the minerals in the bone. This, coupled with the pressure of the hardening sediments, turns the bone into stone.

Fossilized Dinosaur Skull
Fossilized Dinosaur

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