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| | Extinction - Great Dying - Crystalinks |
 | | Organisms throughout the world, regardless of habitat, suffered similar rates of extinction, suggesting that the cause of the event was a global, not local, occurrence, and that it was a sudden event, not a gradual change. |
 | | Many theories have been presented for the cause of the extinction, including plate tectonics, an impact event, a supernova, extreme volcanism, the release of frozen methane hydrate from the ocean beds to cause a greenhouse effect, or some combination of factors. |
 | | The biggest extinction event in Earth's history 250 million years ago The Great Dying, as it is known, is firmly established in the fossil record. |
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