Clues at the Fossil Dig

Digging Up the Past

1Imagine brushing dirt away from a dinosaur bone. For paleontologists, scientists who study fossils, this is an exciting part of the job. A fossil is what is left of a plant or animal that lived long ago. Some fossils are body parts, like bones, teeth, and shells. Others are traces, which are signs that a living thing was once there. Footprints, nests, and tunnels dug by animals can all be traces.

2Many fossils are found in rock that formed from sediment, or loose bits of sand, mud, and tiny pebbles. Over a very long time, layers of sediment piled up and pressed down until they hardened into rock. Wind and rain slowly wear some of that rock away. Sometimes, a fossil begins to peek out.

3When a team finds a bone, they must excavate it. In other words, they dig it out of the ground slowly and carefully. Workers use small implements, such as soft brushes, little picks, and flat hand shovels called trowels. They take their time because old bones are often brittle; that is, they crack and break easily.

4Before anything is moved, the team must document the site. This means they keep a careful record of it. They write notes, draw maps, and take photographs that show exactly where each piece was lying. Later, these records help scientists figure out how all the pieces fit together.

5Large bones often need extra protection for the trip to the lab. Workers wrap them in a plaster jacket, a hard shell made from strips of cloth dipped in wet plaster. Once the plaster dries, the jacket keeps the bone intact, or whole and unbroken, during the bumpy ride.

6At the lab, workers called preparators open the jacket and clean the fossil. Preparators are meticulous. They pay close attention to every tiny detail and do not rush. One slip with a tool could chip off a piece that can never be replaced. It can take months of careful work before a fossil is ready for scientists to study or for visitors to see.