How Are Dinosaur Fossils Formed?

Fossil Formation

A number of factors come into play in the formation of dinosaur fossils. While there are several types of fossilization, including freezing, mummifying and amber, dinosaur fossils are created through permineralization. The animal dies, most often in or near water. Bacteria and scavengers then eat away at the soft tissue while the bones and teeth remain.

Sedimentation

For a dinosaur's remains to have fossilized, sedimentation has to occur quite quickly after the animal's death. Sedimentation, or burial, serves to further preserve the skeletal structure and may even allow some soft tissue details to remain visible in the final fossil. Fossilization is most likely in areas with significant amounts of sand, including river deltas and the bottom of lakes or other bodies of water. Over time, the layers of sediment accumulate, burying the bones deeper and deeper.

Permineralization

The minerals in the sediment-covered bones are slowly over millions of years replaced by the minerals in the sand, now compressed into sedimentary rock. Eventually, the bones become rock, buried deep underground. As the Earth's surface changes and shifts, these deeply buried fossils will move closer to the surface. These fossils may be revealed through erosion or excavations.

Resources

• What is a Fossil?
• Making Fossils