Summary #9 (Evidence of change)

Have you ever seen a footprint in the mud? A footprint is a kind of evidence that a living thing leaves behind. In ancient animals fossils are the evidence that they existed are fossils. Fossils are traces or remains of an organism that haves been preserved in Earth's crust.
Most of the fossils that we find are of animals that no longer exist in Earth.As changes took place in their enviroment, some species were not able to survive and they become extinct. A some species extinct other developed. The idea that species change over time,resulting in new species is called the teory of evolution. There are two types of way fossils can form: mineral replacement and molds and casts. There are two ways the age of a fossil can be tell by: relative dationg and absolute age. There are other clues of evolution on Earth and they are: similar structures and body parts.