Thousands of years of volcanic eruption turned the world's oceans acidic 250 million years ago, leading to a Great Dying, scientists say. Mass extinction killed of 90 percent of marine species and two-thirds of land species, they estimate.(Photo : Christina Arias | Getty Images)
Thousands of years of volcanic eruption turned the world's oceans acidic 250 million years ago, leading to a Great Dying, scientists say. Mass extinction killed of 90 percent of marine species and two-thirds of land species, they estimate.
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