6 Different Fossil Types
The study of fossils is important. It can yield valuable information about what life was like at the time the fossil was formed. Two general classifications define fossils -- body and trace. Body fossils contain part of all of the body of the animal or plant fossilized. Trace fossils are preserved evidence of animal activity such as footprints, trails or even fecal matter.
-
Mold/Cast
-
This is the most common type of fossil and occurs when an animal or plant dies in a wet setting and gets covered or buried in layers of mud or silt. The mud and silt become sedimentary rock, which form around the remains of the plant or animal. Eventually, the organic matter decays, leaving a hollowed out mold. Water and sediment settle in the mold and harden due to the mineral content of the water. This results in a model of the original organic matter, which is called a cast.
Mineral Replacement
-
This is another type of body fossil. With a mineral replacement fossil the process is similar to the mold and cast. Instead, mineral-enriched groundwater seeps into the mold. However, the mineral solution permeates the microscopic spaces of the shells, teeth, bones or woody plant tissues. The minerals eventually crystallize and take the shape of the originial plant or animal as a type of statue. Petrified wood is an example of mineral replacement, too.
-
Preserved Remains
-
Preserved remains or true form fossils occur when the actual animal or plant is fossilized in amber or some other substance, preserving them in or near entirety. Amber comes from tree resin that solidifies. Other methods of preserving remains can occur with freezing, such as in glaciers, or in sticky tar pits or peat bogs.
Trace Fossils
-
Trace fossils include trails, walkways, footprints, dwellings such as nests or habitats and even coprolites, which is fossilized fecal matter. Scientists study trace fossils to learn about the the size of the animal/plant and how animals moved, traveled, lived -- such as whether in groups or alone. They learn how the animal or plant lived and where, not just the way they died, all learned from trace fossils.
-
References
- Photo Credit Hemera Technologies/Photos.com/Getty Images
