Ask-a-Geologist #10: What Are The Remains Of Once-Living Organisms Found In Sedimentary Rocks?

Fossils are the remains or impressions of once living organisms that you can find in sedimentary rocks. There are two basic types of fossils that geologists and paleontologists talk about. These are body fossils and trace fossils. Body fossils are a real body part of an animal such as a dinosaur bone or a shark tooth. A trace fossil is something that shows evidence that something was there such as tracks, burrows, trails, molds, casts, and impressions.