Fossils in Sedimentary Rocks

Oh no! Your little brother, JJ, got into your room again! This time he really messed up your toy car collection. You decide to plead your case with your mom. You explain to her that you would like a lock on your door to protect your belongings. Your mom tells you that there is no proof that JJ has been in your room because no one saw him go in there. Your mother tells you that you will have to prove JJ was in your room before she will grant you your wish. How can you prove your case?

You decide that it's time to put a stop to the little room invader. You accept your mother's challenge. You are going to investigate to find evidence in support of your hypothesis. If you examine the carpet carefully, tiny sandal footprints can be seen. What's that on your pillow? It's cookie crumbs and red hair that is a perfect match for a certain two year old in your family. Now you've got him for sure! His favorite "blankie" is stuffed in your drawer. You bring all the evidence together and present it to your mom. The decision is in. "Good detective work," your mother says with a sigh, "you have your lock!"

Just as your little brother left evidence of his visit to your room, some plants and animals which lived on the Earth long ago left clues of past life that science detectives have discovered. These clues are called fossils. So grab your notepad and magnifying glass and get started on the most exciting case ever. It is time to investigate the "Great Fossil Mystery."

Fossils are the evidence of plants or animals which lived on Earth long ago. Scientists examine this evidence to make inferences about what happened on Earth millions of years ago. Fossils are usually found in rocks and are the preserved remains of a once living thing. To become a fossil, most organisms must have hard parts such as bones or shells since the soft parts decay before they are fossilized. The plant or animal must be buried quickly to prevent decay. It must also remain undisturbed for a long period of time. A fossil might be the thigh bone of a triceratops or the petrified trunk of a tree.

Sometimes a fossil is just a mark left behind by an organism when it was alive such as a trail, a burrow, or a track. These are called trace fossils. Dinosaur footprints are often found in the roofs of coal mines in Carbon County. Were the dinosaurs walking upside-down? Think about it...does this make sense. Perhaps it would be more accurate to say that the coal formed under the material that the dinosaur stepped on.

Some rare organisms are preserved unaltered (unchanged). This might happen when an animal falls through ice or into a tar pit. Some insects such as mosquitos have been preserved in amber (fossilized sap from ancient trees). Most plants and animals that lived in the past died without leaving a trace.