Fossil Facts

Fossils are what's left of plants and animals that were alive a long time ago. When the plant or animal died, part of it was left on the earth. That part became trapped in the sediments, and the sediments became rock. Once the rock formed, the fossil was trapped inside. Some fossils are destroyed because sediments undergo a lot of heat and pressure when they become rocks, and the heat and pressure might destroy the fossils. Most fossils are found in sedimentary rocks.

There are two types of fossils:  vertebrate and invertebrate. Vertebrate fossils come from animals that had bones. Invertebrate fossils come from plants or animals that didn't have bones.

Sometimes fossils are parts of bodies like bones and teeth. Sometimes they are parts of leaves. Other times they might be animal tracks.

When a plant or animal leaves a shape, that shape is called a mold. If mud or minerals fill the mold and harden, that's called a cast. It has the same shape that the animal or plant had when it was alive. Imprints are molds of thin objects like leaves. Wings and feathers can also leave imprints because they are very thin.

A fossil isn’t the actual bone or leaf or other object that was left. Instead, it’s just an object that’s the same shape as the original item. It’s made up of various minerals and other material that has hardened.

We can use fossils to help us learn about the animals or plants that have died. This kind of study is called paleontology. Scientists have used fossil bones to put together skeletons of dinosaurs and other animals. We can tell how large they were and how they walked by looking at the skeletons. The teeth of the fossils show what kinds of foods they ate. Sharp teeth probably mean the dinosaurs ate meat (other dinosaurs). Flat teeth probably mean the dinosaurs ate plants.