geologic time crossword

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Across
  1. 4. The supercontinent that once was all together?
  2. 7. What are animals without a backbone?
  3. 8. Geologists further subdivide the periods of the cenozoic?
  4. 9. What were the first fishes to evolved and the first vertebrates?
  5. 11. A kind of animal that lives part of their life in the water and on land?
Down
  1. 1. What are animals with a backbone?
  2. 2. Time and the present into three long units of time?
  3. 3. What was the time when 95% of the animals and plants disappeared?
  4. 5. The first vertebrates to crawl onto land?
  5. 6. The era that lasted 300 million years?
  6. 10. Eras broken down even more?
  7. 12. What kind of animal is warm-blooded vertebrates who feed their young milk?