Across
- 4. cavity left by deceased organisms body
- 5. example of a trace fossil
- 8. rate of radioactive decay
- 9. studies Earth
- 10. First geological period of the Paleozoic Era
- 14. extinct marine arthropod
- 15. Period of First Dinosaurs
- 17. Earth Science Teacher
- 18. preserved remains, impression, or trace of any once-living thing
- 20. the study of rock layers
- 22. Top Jurassic Predator
- 25. many organisms die
- 26. the world's first true vertebrates
- 27. covered entire continents during ice ages
Down
- 1. hazard to ancient organisms
- 2. Layers of Rock
- 3. Ruled after birds
- 5. 4.6 _____ years
- 6. burial condition for fossil formation
- 7. rock where most fossils are found
- 11. large extinct marine reptile
- 12. studies prehistoric life
- 13. Ruled after Dinosaurs
- 16. many layers of this build glaciers
- 19. Organism with no spine
- 21. lives part on land part in water
- 23. The most recent Super-continent
- 24. dating rock by comparison of known layers