Geologic time puzzle

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Across
  1. 2. Initial formation of the earth
  2. 5. Age of reptiles
  3. 6. First vertebrate animals colonized land
  4. 8. Oldest animal fossils
Down
  1. 1. Transition to an oxygen atmosphere
  2. 3. Formation of Rodinia supercontinent
  3. 4. Age of Mammals
  4. 7. Oldest Known rocks