Mystery Message #1

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Across
  1. 3. hind part
  2. 5. large quantity
  3. 7. body of writing
  4. 9. similar words
  5. 11. past, present and future
  6. 12. which
  7. 13. long dead
  8. 14. has knowledge of
  9. 15. loud yell
  10. 16. vocabulary
  11. 17. novel
  12. 19. petrified remains
Down
  1. 1. chronicle of events
  2. 2. long gone
  3. 4. parts of a skeleton
  4. 6. prehistoric lizard
  5. 8. length of time
  6. 10. backbone
  7. 11. book of related words
  8. 15. mineral matter
  9. 18. nail
  10. 20. ancient
  11. 21. identical