1. Hadean eon toxic atmosphere; first bacteria 2. Archean eon formation of the solar system 3. Proterozoic eon buildup of oxygen; first eukaryotes 4. Phanerozoic eon current eon

1. Hadean eon: C. formation of the solar system

2. Archean eon: A. toxic atmosphere; first bacteria

3. Proterozoic eon: B. buildup of oxygen; first eukaryotes/

4. Phanerozoic eon: G. current eon

5. Paleozoic era: F. largest mass extinction in Earth's history

6. Mesozoic era: E. time of the dinosaurs

7. Cenozoic era: D. sometimes called "Age of Mammals"