How does knowledge of sedimentary rock formation help us to understand fossils?

Sedimentary rocks are formed when sediment is deposited out of air, ice, wind, gravity, or water flows carrying the particles in suspension. This sediment is often formed when weathering and erosion break down a rock into loose material in a source area.

Sedimentary rocks tell us about past environments at Earth's surface. Because of this, they are the primary story-tellers of past climate, life, and major events at Earth's surface. Each type of environment has particular processes that occurred in it that caused a particular type of sediment to be deposited there.

Permineralization: This is the most common procedure of fossilization. It is also known as petrification. After an organism's soft tissues decay in sediment, the hard parts — particularly the bones — are left behind. Water seeps into the remains, and minerals dissolved in the water seep into the spaces within the remains, where they form crystals.  These crystallized minerals cause the remains to harden along with the encasing sedimentary rock.

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