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How do Fossils form?
They're not just bones that end up underground waiting to be dug out.
The word fossil itself comes from the Classical Latin word Fossilis, which means obtained
by digging.
But as we know some fossils can be obtained without digging.
There are 4 types of fossils, mold, cast, trace and true form fossils.
Mold fossils are impressions, without the bones themselves.
Cast fossils are basically mold fossils but are filled in, typically with minerals.
Trace fossils are traces of the existence of the creature, such as nests, burrows or
tracks.
True form fossils actually have parts of the animal, typically bones.
There are many types of true form fossilization, but two main kinds are unaltered preservation
and permineralization, which is what we will be focusing on today.
Unaltered preservation is most common in insects and other small creatures.
It is when they are trapped in a thick substance which hardens, preserving all parts of their
body.
This substance is typically amber, which is hardened tree sap.
permineralization is when rock like minerals seep into the animal and replace its organic
tissue and sometimes bone.
This is why fossilized animals seem to have dense bones, it is because of the minerals
that seeped in.
One way this can happen is in a body of water.
The animal will settle at the bottom, and the decomposition process will be greatly
slowed by the surrounding water.
Eventually sediment will cover the body, and more and more layers of rock will cover it
on top.
This pressure will cause permineralization.
Eventually, due to geologic forces, the fossils may be closer to the surface or even above
ground which is where we can discover them.
Though now without technology and our knowledge of migration patterns and habitats we can
accurately predict and find fossils underground, in the past we had to rely on chance to stumble
upon something great.
I hope you enjoyed this video as much as I appreciated you watching.
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