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KidZone Animals: Dinosaurs

trex skull
Fossilized Tyrannosaurus Rex Skull
Photo by Brett Meliti on Unsplash

A fossil is ancient life that has been preserved, which often means being turned into a different material like rock or minerals. A fossil can only be made if the ancient life is buried enough. The general rule of thumb for fossil burial is that the more quickly and thoroughly a fossil is buried the better the quality of the fossil. Also, ancient life can only be preserved if it is buried in sedimentary rock.

Here is a quick crash course in rock types:

Fossils can't typically form in igneous rocks or metamorphic rocks because the ancient life would have to be buried and then heated up, which would often destroy the fossil. Whereas sedimentary rocks preserve the fossils instead of destroying them.

Once a fossil has been buried, there are a bunch of different ways to make a fossil depending on the type of ancient life that has been buried. I haven't explained every type of fossilization but I have included a few different methods:

hadrosaurus fossil in a museum
A mold of a mesoaurus skeleton.
Photographed by Tee La Rosa;
used with permission under CC BY-ND 2.0

One of the key facts about fossilization is that soft materials in ancient life aren't typically preserved. That is why we find a lot of skeletons and bones but very little soft tissues like skin or organs. However, sometimes we get some really cool cases of near-perfect preservation or mummification.