The Devonian period, which occurred 419 to 358 million years ago, prior to the evolution of life on land, is known for a series of catastrophic mass extinction events, during which it’s estimated nearly 70% of all life on Earth went extinct. New research shows that the evolution of tree roots likely flooded past oceans with excess nutrients, causing massive algae growth; these destructive algae blooms would have depleted most of the oceans’ oxygen, triggering mass extinctions.
[Evidence comes from] utilizing geochemical records from ancient lake deposits in Greenland, northern Scotland, and Orkney.
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