Across
- 4. Believed to have caused extinction of dinosaurs
- 7. Period of the cenozoic the present era, that are further divided
- 8. began about 65 million years ago with the cretaceous mass extinction and continues to present
- 10. stretches from about 2.6 million years ago to the present
Down
- 1. a period when dinosaurs lived
- 2. Eon The atmosphere had no free oxygen until
- 3. began about 540 million years ago as the global supercontinent pannotia was breaking up
- 5. Paleozoic, mesozoic, and cenozoic
- 6. Much for Earth's land surfaces were located near the poles and covered in ice
- 9. Released oxygen in the air during the process of photosynthesis