Sometime a fossil is the result of a volcanic eruption. Ash and mud from the volcano can cover animals and plants killing and preserving them at the same time. Fossils come in all sizes. The study of fossils is called Paleontology . The study of fossil plants is Paleobotany .
Fossils exist all over the world.
As hills erode, fossils become visible and a Paleontologist can find and remove them for study. Sometimes a small area only a few hundred feet across will be jammed with skeletal remains. A bone bed maybe the site of a sandbar on an ancient river. During floods, the bodies of many animals floated downsteam, grounded on the bar, and quickly got covered with silt and were preserved. Removal of fossils from the rock is done very carefully to avoid damage to the specimen.