What Can Fossils Tell Us

Fossils are the preserved remains or traces of plants and animals that lived long ago. A fossil might be a bone, a shell, a footprint, or even an imprint of a leaf in rock. Scientists study fossils to learn about Earth's history because fossils provide important clues about the past.

Fossils tell us what kinds of organisms lived millions of years ago. When scientists find dinosaur fossils, they can figure out what dinosaurs looked like, how big they were, and what they ate. Fossils also reveal information about ancient environments—the surroundings where organisms lived. For example, if scientists find a fish fossil in the middle of a desert, they know that area was once covered by water. This shows that Earth's surface has changed over time.

Fossils also show that life on Earth has changed dramatically. The organisms preserved in fossils look very different from plants and animals alive today. Some fossils are of organisms that are now extinct—they no longer exist anywhere on Earth. Dinosaurs are the most famous extinct organisms. By studying fossils, scientists learn that some species disappeared while new species appeared over millions of years.

Fossils are found most often in sedimentary rock—rock formed from layers of mud, sand, and other materials that settled at the bottom of oceans, lakes, and rivers. Fossils are one of the best tools scientists have for understanding Earth's long history.

Interesting Fact: The oldest fossils ever discovered are about 3.5 billion years old! They are fossils of tiny bacteria-like organisms that lived in ancient oceans.