Across
- 4. the first animals that left the ocean for land
- 6. Era where bacteria formed
- 7. Era where complex life began to form
- 9. animals without a backbone
- 11. one of the first life forms still alive today
Down
- 1. the majority of early life was this: did not move
- 2. evidence of an organism, why we have so much proof of Paleozoic era
- 3. blue green algae, first to take in sunlight
- 5. responsible for mass extinction, and changing of the Earth
- 8. the earliest life forms relied on this energy to survive
- 10. process that cyanobacteria used to make energy