How Are Fossils Made?
Precambrian Eon

4,600 - 541 mya

Paleozoic EraPaleozoic.html
541 - 252 myaPaleozoic.html
Mesozoic EraMesozoic.html
252 - 66 myaMesozoic.html
Cenozoic EraCenozoic.html
66 mya - presentCenozoic.html

Copyrighted by Colossal Fossils Inc. for the next 65 millions years...

Fossils used to be living creatures...

Only things that were alive at one time can become a fossil.  This would include plants and animals.

For our example, we will use Triceratops...

66 million years ago, Triceratops may have spent some of its time living on floodplains, in states like South Dakota when the climate was much warmer than it is today.

Then the plant or animal dies...

When the Triceratops died, its body was quickly covered with mud or sand.  This could have happened from a flood or just the wind blowing.  Getting covered in soil would have protected its body from being eaten by scavengers.  It also would have helped keep bacteria from destroying it.

Turning to stone...

Over time, layer upon layer of new soil would have buried the skeleton deeper and deeper.  As the soil grew in thickness, it would have become harder from the intense pressure, eventually turning to stone over millions of years.  The bones too would eventually be replaced by minerals as ground water seeped through the bones, replacing the organic tissues with hard minerals.

Digging up dinosaurs...

Millions of years later, wind and water slowly erode the rock, exposing the skeleton.  That is when people find them while walking around.  Scientists come to dig the bones up, and reassemble them in museums for you to enjoy!


  1. Oxford University Museum of Natural History. (2006). The Learning Zone: How do Fossils Form. Retrieved from

  2. New York State Geological Survey. (2013). How are Fossils Formed. Retrieved from