Earth Science

How Fossilization Creates Fossils

How Fossilization Creates Fossils

Study Tip
Trace fossils reveal traces and patterns from the organism’s life. Body fossils, on the other hand, only show the body and the physical characteristics.

Fossil Types

  • In 1666, Nicholas Steno discovered that fossils are remains or traces of ancient species.
  • There are two different types of fossils, trace fossils and body fossils.
  • Trace fossils are burrows, tracks, or feces of ancient organisms that have been preserved over time.
  • Body fossils are the parts of a body of an ancient organism that are left behind after the soft parts have decayed.
Study Tip
Trace fossils reveal traces and patterns from the organism’s life. Body fossils, on the other hand, only show the body and the physical characteristics.

Fossil Creation

  • Only a small percentage of the organisms that have ever lived become fossils.
  • There are several conditions that determine if an organism will become a fossil.
  • The organism has to have hard body parts as bones, teeth, and shells, which are usually the parts that are preserved. Most of an organism’s soft parts decay quickly, leaving behind hard parts such as bones and shells behind.
  • The organism must have experienced a quick burial. Most decay occurs at the surface, so a quick burial can help preserve the remains of the organism.
  • Sometimes unusual circumstances can help to preserve the remains of an organism. For example, if the organism were trapped in tar, the remains would be perfectly preserved.
  • Some soft-bodied organisms are preserved in rock beds around the world. These fossils are unusual because soft-bodied organisms are generally not preserved.
Fossil Creation
The hard parts of the organisms shown here remain preserved after the soft parts deteriorate.
Concept Check
  • How do trace fossils and body fossils help scientists in different ways? What different information do they allow scientists to gather?
  • What are the differences between trace fossils and body fossils?