Geological Time Scale

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Across
  1. 5. extinction of dinosaurs
  2. 6. first fishes
  3. 7. how many eras are there
  4. 8. peroid when humans evolved
  5. 9. eons are divided into
Down
  1. 1. largest defined unit of time
  2. 2. the peroid we live in
  3. 3. the study of fossils
  4. 4. the era of reptiles