What is a Fossil?

Part of the Dinosaurs: Activities and Lesson Plans Curriculum Collection.

What is a Fossil activity listing image

The American Museum of Natural History houses the largest and most spectacular collection of vertebrate fossils in the world. A fossil is any evidence of prehistoric life that is at least 10,000 years old. The most common fossils are bones and teeth, but footprints and skin impressions fossils as well. Fossils are excavated from ancient riverbeds and lakes, caves, volcanic ash falls, and tar pits. Fossils are classified as either body fossils or trace fossils. Body fossils were parts of the organism, such as bones or teeth. Trace fossils include foot impressions, eggs, burrows, and dung.


In this activity, students will learn to distinguish between body fossils and trace fossils.


  • Body Fossils and Trace Fossils duplicated for each student
  • Crayons
  • Pictures of fossils


  1. Write the word fossil on the chalkboard and have students describe what a fossil is in their own words. Guide students to understand that a fossil is any evidence of life that is at least 10,000 years old. Further explain that dinosaur fossils are much older. Some are 65 million years old, others are more than 225 million years old. Tell students that paleontologists can learn a lot about life long ago by studying the fossils they find. Tell students they will explore different kinds of fossils.
  2. Write the words body and trace in two columns on the chalkboard. Tell students that fossils are classified as body fossils and trace fossils. Body fossils were once part of an animal. Display pictures of the body fossils. Have students identify the skull, tooth, and foot. Write their answers in the column marked “body.” Further explain that trace fossils are evidence of something the dinosaur left behind. Display pictures of the trace fossils. Have students identify the footprints, eggs, and skin impression. Write their responses in the column marked trace. Allow students time to share other information they have about fossils.
  3. Distribute crayons and copies of Body Fossil and Trace Fossils. Instruct students to look at the fossils pictured and decide whether they are body fossils or trace fossils. Have them circle the body fossils blue and the trace fossils red. (Answers: tooth, skull, and foot are body fossils. Skin imprint, eggs, and footprints are trace fossils.)