| 11. | The second came 360 million or so years ago during the Devonian Period.
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| 12. | During the Devonian period the local seas deepened and their oxygen levels dropped.
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| 13. | The fault is most likely younger than the Jacobsville Formation and the Devonian Period.
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| 14. | Paleogeographic reconstruction showing the Michigan Basin area during the Middle Devonian period . ]]
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| 15. | The oldest types of tetrapod tail-and-foot prints date back to the latter Devonian period.
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| 16. | During the Devonian period, vascular plants diversified and spread to many different land environments.
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| 17. | The formation of the Ausable Arkona has exposed fossils from the Middle Devonian period.
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| 18. | Paleogeographic reconstruction showing the Appalachian Basin area during the Middle Devonian period . ]]
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| 19. | Up to long, these eurypterids are found from the Ordovician to the Devonian periods.
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| 20. | This occurred around 370 million years ago ( in the Late Devonian period ).
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