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. Subscribe to stay

up to date on all my latest science videos, and until next time, Cram out.