History of Life

1. to keep or save
6. younger layers of rock and fossils are usually on top of older layers of rock
8. particles of gravel, sand, and mud
10. preserved parts of organisms or evidence of activities
11. different kinds of living things, like we have on Earth
12. when the last organism of its kind dies, we say it is ________
15. the type of rock most fossils are found in
16. organisms must have these to become fossils

2. the name for fossil dating that uses the principle of superposition
3. preserved evidence of activities
4. a mythical creature prone to misadventure that looks like a horse and has a horn
5. ancient and modern tetrapods share the same _ _ _ _ _ _ _ _ _ _ _ _ _
7. every fossil that has been discovered
9. any living thing
13. an organism with four limbs
14. rock made from parts of an organism