Across
- 2. hard pieces that form the frame of each human
- 6. a long period of history with occurring events
- 7. wind, water or other natural agents
- 9. to adjust to its surroundings
- 10. mass extinction of about 90% of marine species and 70% of terrestrial species
- 11. Also known as "The Age Of The Dinosaurs"
- 13. extinction of a large number of species
- 15. a layer filled with sedimentary rock from the same age
- 17. presence of numerous marine algae species
- 18. appearance of first flowering plants
- 20. a solid inorganic substance
Down
- 1. appearance of first amphibians and insects
- 3. multiplication of reptile and insect species
- 4. a star, main source of light and heat in the solar system
- 5. formed by compressed sediments
- 8. when the remains of an organism harden
- 12. preserved remains of an organism
- 14. the result of a force applied to a surface
- 15. group of organisms that can reproduce
- 16. person who studies the ancient life
- 19. appearance of 1st dinosaurs