Water Dwellers

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Across
  1. 4. large predatory lobe-finned fish
  2. 6. giant scorpion
  3. 7. very widespread extinct marine arthropod
Down
  1. 1. “old” + “life”
  2. 2. earliest period for classic fossil record
  3. 3. “the Old Red Age”
  4. 5. initial establishment of terrestrial life