Across
- 4. way to determine a fossil's age through its placement in rock formations
- 8. when all the organisms in a species die; there are no more of that species alive
- 9. the time it takes for half the isotopes in a radioisotope to decay
- 10. average and one extreme are more fit to survive
- 11. selection survival of the fittest
- 12. when a species conceals itself within its environment
- 13. the organism's ability to survive and reproduce in an environment
- 14. when a population becomes a distinct species
Down
- 1. structure that appears in multiple different species
- 2. change over time
- 3. both extremes are more fit to survive than the average
- 5. remains of ancient organisms
- 6. all the possible genes in a population
- 7. features a species gains that helps it survive in its environment