The fossil record is incomplete. Of the small proportion of organisms preserved as fossils, only a tiny fraction have been recovered and studied by paleontologists. In some cases the succession of forms over time has been reconstructed in detail. One example is the evolution of the horse.

Recrystallization – A process by which the minerals making up the original shell or bone of a fossil change into a different mineral made of the same chemical components. Commonly, fossil shells made of aragonite will recrystallize into a more stable form of the same compound called calcite.

Five different types of fossils are body fossils, molds and casts, petrification fossils, footprints and trackways, and coprolites.

There are two types of fossils- the body fossils and the trace fossils. Body fossils include preserved remains of an organism (i.e. freezing, drying, petrification, permineralization, bacteria and algea).

Fossils give us information about how animals and plants lived in the past. By studying the fossil record we can tell how long life has existed on Earth, and how different plants and animals are related to each other.

Trace fossils are useful for paleontologists because they tell about the activity of ancient organisms. Paleontologists can also estimate dinosaur gait and speed from some footprint track ways. If the footprints are close together, this might show they were running.

The youngest person to find a fossil was an American boy named David Shiffler. He was just three years old when he found a piece of a fossilized dinosaur eggshell in New Mexico.

8 So, what does the fossil of the seashells found in the woods tell scientists? It tells them that the earth once looked very different than it does now. This fossil indicates that those woods were once covered by an ocean. 9 The fossil record can also show us how the earth’s climate has changed over time.

Some have become extinct. A type of organism is extinct if it no longer exists and will never again live on Earth.

To establish the age of a rock or a fossil, researchers use some type of clock to determine the date it was formed. Geologists commonly use radiometric dating methods, based on the natural radioactive decay of certain elements such as potassium and carbon, as reliable clocks to date ancient events.

Fossils found in rock include molds and casts, petrified fossils, carbon films, and trace fossils. Other fossils form when the remains of organisms are preserved in substances such as tar, amber, or ice.

4.54 billion years