Fossil Evidence for Kids: Reading Earth’s History in Rock (Grades 6 to 8 Science)

Hi, I'm Luna from DoodleBeez. Fossils are the preserved remains or traces of living things from long ago. They are like clues in a giant mystery, telling us how life on Earth has changed.

Most fossils form in sedimentary rock. An organism dies and is quickly buried by mud or sand. Over time, layers pile up and harden into rock. Minerals can slowly replace the bones or shell.

There are several kinds of fossils. Body fossils are bones, teeth and shells. Trace fossils, like footprints and burrows, show how animals lived. Some insects were trapped in tree sap that hardened into amber.

Rock layers stack up over time, so lower layers are usually older than the layers above them. This is called the law of superposition. Fossils in deeper layers usually lived earlier.

The fossil record shows that life has changed over time. Many organisms, like trilobites and most dinosaurs, went extinct. Simpler life appears in older rocks, and newer forms appear in younger rocks.

Fossils can show how groups of living things are related. For example, fossils of early whales show ancestors that had legs and lived partly on land. This helps scientists trace how whales changed.

Now it's your turn. A fern fossil is found in a deep rock layer, and a shell fossil is found in a layer above it. Which is older? Pause and try. The fern fossil is older, because deeper layers formed first.

Great job! Remember, fossils form mostly in sedimentary rock. Deeper layers are usually older, and the fossil record shows how life has changed. Practice fossil evidence in the Science Lab at doodlebeez.com. See you next time!