If an organism did not use part of its body, it was believed, that that part would wither and deteriorate. In this book he put forth 2 main points concerning organisms and the environment. Here he tried to explain how modern organisms developed from a common ancient ancestor. The theory of evolution would not be around today unless it had factual data to back it up. Certain process are used to date ancient fossils.
Comparative anatomy is another method used to actualize evolution.
Here organs are compared and determined if they have a similar ancestry. An area of sedimentary rock was being examined for fossils. The area was once believed to be inhabited by many forms of life. Geologists believed the area was between 100 million and 150 million years old. Below find a chart containing the data based on their findings.