Evolution

4. The remains or traces of ancient organisms preserved in rock.
8. The process by which humans select traits in organisms to breed.
9. Islands where Darwin studied species that led to his theory of evolution.
10. The formation of new and distinct species in the course of evolution.
13. Differences between individuals of the same species.
17. A scientist who studies fossils.
18. Body parts in different species that have similar structures and a common evolutionary origin.
19. The surroundings or conditions in which an organism lives.
20. The scientist who proposed the theory of natural selection.
21. Small birds that were studied by Darwin on the Galapagos Islands.

1. The gradual change of species over time.
2. The collection of all fossils that provide evidence of past life.
3. The most recent species from which two or more species have evolved.
5. The ability of an organism to survive and reproduce in its environment.
6. Body parts that have lost their original function through evolution.
7. A trait that helps an organism survive in its environment.
11. The ability of an organism to blend in with its environment.
12. The process by which organisms with favorable traits are more likely to survive and reproduce.
14. A change in an organism's DNA that can lead to a new trait.
15. Large marine mammals that evolved from land-dwelling ancestors.
16. Animals with a backbone or spinal column.