or silt on the sea floor. Land animals and plants usually decomposed or were eaten, and mainly the hard parts -- teeth, bones, shells, or wood -- were preserved. Fossils can be formed in several ways.

Sharks have ruled the Earth’s oceans for 400 million years and recent research on fossilized shark teeth has led to the discovery of an innovative method for dating ancient sediments.

If you'd stopped monitoring the Adriatic Sea's marine life in the mid-20th century ... find an abundance of this species in ...

Ammonites were shelled cephalopods that died out about 66 million years ago. Fossils of them are found all around the world, sometimes in very large concentrations. The often tightly wound shells of ...