Evolutionary!

4. A difference in a physical trait.
6. Charles________ was the "father of evolution".
7. The gradual biological process of change by which descendants begin to greatly differ from their ancestors.
9. Man who theorized that environmental change leads to the use or disuse of a structure.
10. The man who developed the theory that natural disasters shaped the earth's landforms and caused extinction.(Full name)
12. Structure or organ that are similar structure, but different in purpose.
15. A natural mechanism by which a species, or member of that species inherits a beneficial adaptation that allows it to produce more offspring than others.
17. The measure of survival ability and ability to produce for offspring.
18. The English naturalist who independently developed a theory of evolution. (Full name)
19. The ability for a trait to be passed down.
20. The last name of the scientist who cam up with the theory that species shared common ancestors, rather than coming into being separately.

1. A preserved trace of an organism from the past.
2. The last name of the scientist who developed the classification system.
3. The theory that natural disasters shaped the earth's landforms and caused extinction.
5. Study of embryos, used to find similarities between species during development.
8. The man who came up with the theory of gradualism. (Full name)
11. The process by which humans select traits through breeding.
13. Producing more offspring than will likely survive.
14. The idea that geologic processes that shape the earth remain constant over time.
16. A feature that an organism develops to better survive in it's environment.