Scientists now know what caused mass extinctions on Earth 420 million years ago
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Florida state university researchers found that around 420 million years ago, a devastating mass extinction called Lau/Kozlowskii extinction wiped around 23% of all marine animals from the Earth. Scientists struggled for long to find the reason for this mass extinction, and they finally found an answer. The mass extinction was triggered by rapid and widespread depletion of oxygen in the global oceans.