Across
- 4. Ice age occurs in this time period
- 5. Age of the fishes
- 6. Period in which Pangea forms
- 8. Salt flats
- 11. Swimming reptiles
- 13. Index fossil that becomes extinct
- 14. Oldest rock formation
- 15. present day era of life
- 17. Age of the dinosaurs
- 19. Himalayan mountains form in this time
- 20. Period when the rocky mountains form
Down
- 1. Mats of algae
- 2. First birds
- 3. Organism without a backbone
- 7. Era that begins with the Cambrian period
- 9. Time period in which Pangea broke up
- 10. An exposed layer of craton
- 12. Animals with out of water proof covering
- 16. Example of a single cellular organism
- 18. example of a multicellular organism