Flexi Says: Quick burial is essential for fossil formation because most decay and fragmentation occurs at the surface. Quick burial is rare on land, so fossils of land animals and plants are less common than marine fossils. Land organisms can be buried by mudslides, volcanic ash, or covered by sand in a sandstorm. Skeletons can be covered by mud in lakes, swamps, or bogs. Usually, it’s only the hard parts that are fossilized. The fossil record consists almost entirely of the shells, bones, or other hard parts of animals. Teeth are much more resistant than other bones, so a large portion of the mammal fossil record consists of teeth.
