How Fossil Forms

Click through the stages to see how a fossil is formed over time.

Living Organism

Stage 1: A living organism, like a dinosaur, dies and its body is left on the ground, eventually becoming covered by sediment.

Buried in Sediment

Stage 2: Over time, the organism gets buried by layers of mud, sand, and sediment.

Mineralization

Stage 3: Mineralization – The soft parts of the organism decay, but minerals replace the hard parts like bones, turning them into stone.

Sediments Harden

Stage 4: Lithification – Over millions of years, the sediments around the fossil harden into rock, protecting it.

Fossil Discovery

Stage 5: Fossil Discovery – Erosion or digging exposes the fossil, and it is discovered by a paleontologist!