Changes Over Time

2. Trace fossils left behind by PLANTS or animals lacking bones or shells
3. British naturalist who formulated the theory of Evolution by natural selection
7. The natural process by which organisms best adjusted to their environment are most successful in surviving and reproducing
9. The preserved remains or traces of an organism that lived in the past
10. Used to determine the approximate age of fossils based on the location in layers of sediment
13. A scientist who studies the history of life on Earth through the fossil record
14. Any change in the DNA of an organism
15. The variety of organisms that inhabit the Earth
16. Used to determine the actual age of fossils using radioactive elements
17. The gradual change in species over time
18. Similar animals in different locations adapted differently to separate environments

1. In early stages of development, many species look similar. This provides evidence that they share common ancestry
4. The disappearance of all members of a species from Earth
5. History of life documented by fossils of organisms from earlier geological periods preserved in sedimentary rock
6. Similar structures that related species have inherited from a common ancestor
8. Any difference between organisms of the same species
11. Behavior or physical characteristic that allows an organism to survive and reproduce in its environment
12. A process by which individuals that are better adapted to their environment are more likely to survive and reproduce than others that are not