Across
- 4. Method of finding absolute age of rock based on comparing the amounts of unstable radioactive particles to stable particles
- 6. The remains or traces of once-living organisms
- 7. The study of the development of unborn or unhatched organisms
- 8. The collection of all known fossils and their placement in order
Down
- 1. Theory, based on scientific evidence, that describes how organisms change over many generations
- 2. An organism's body structure
- 3. When all members of a species die out
- 5. A species from which two or more species evolved