Across
- 4. ice age where reptiles started to appear on Earth
- 5. worst mass extinction
- 8. animals in fossil record who first started sharing DNA between two organisms for offspring
- 9. force that pulled matter together to create Earth
- 10. first continent formed when plate tectonics began
- 11. type of animals that ruled Earth after the extinction of dinosaurs
- 13. earliest form of life
- 14. extinction that wiped out 80% of life but made it possible for dinosaurs to rule afterwards
- 15. these types of animals flourished in the oceans after the Ordovician Silurian mass extinction
- 16. animal that modern birds are based on
Down
- 1. when Eukaryotes started to to harness different forms of energy by eating these bacteria
- 2. the earliest form of photosynthesis did not free up this element
- 3. flowers first appeared on Earth when these massive creatures were alive
- 4. the famous super continent
- 5. did plants or animals appear on land first
- 6. type of organism that appeared on land after plants
- 7. time era where many animals started to appear
- 9. when oxygen started to form in the atmosphere
- 12. first complex organisms deriving from the frozen Earth 200 million years ago