So now, some scientists think the dinosaurs could have been victims of a global chemical reaction. With new dino discoveries and more advanced ways of studying fossils, we might figure out how dinosaurs lived. Soon after an animal dies, mud, dirt or sand begins to cover its body. Soft portions of the body decay and the sediment around the bones harden to rock. Minerals in the water petrify these bones and, with time, the layers of rock shift.
Nature exposes the fossil by using wind and rain to wear away the layers of rock.
How Fossils are Formed Dinosaurs might be some of the most exciting fossils around, but lots of other living things were also preserved in stone through the ages. A fossil is the mark or remains of a prehistoric plant or animal thousands of millions of years old. Some fossils are bones, teeth or shells. Others are just footprints. Bones turn to stone when mineral-rich water soaks into their pores.