Evolution: a mass extinction in the late Devonian (Introduction)

by David Turell , Wednesday, March 15, 2023, 18:55 (617 days ago) @ David Turell

Studies in 350 million year-old shale:

https://www.livescience.com/one-of-earths-biggest-mass-extinctions-caused-by-rising-sea...

"Depleting oxygen and rising hydrogen sulfide levels in the oceans may have been responsible for one of Earth's most significant mass extinctions more than 350 million years ago, a new study finds.

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"Researchers studied samples of black shale from the Bakken Formation, a 200,000-square-mile (518,000 square kilometers) region partly laid down during the late Devonian that encompasses parts of North Dakota and Canada and is one of the largest contiguous deposits of natural gas and oil(opens in new tab) in the United States. The team found evidence that Earth experienced periods of oxygen depletion and hydrogen sulfide expansion, which likely contributed to the sweeping extinction events that ravaged Earth during the Devonian period (419.2 and 358.9 million years ago), or the "Age of Fishes."

"Hydrogen sulfide forms when algae decomposes on the ocean floor. The decomposition process also depletes the area of oxygen.

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"To better the Devonian extinctions, the research team analyzed more than 100 core samples drilled from black shale deposits in the Bakken Formation. This organic-rich sediment accumulated near the end of the Devonian period, recording the environment within its chemical makeup.

"The team found evidence of "anoxic events," where waters were completely depleted of oxygen, they reported in the study, published March 8 in the journal Nature(opens in new tab).

These sharp drops "are likely linked to a series of rapid rises in sea level" due to the melting of South Pole ice sheets during the preceding Silurian period (443.8 million to 419 million years ago), Kaufman said in the statement.

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"Simultaneously, plants transformed rocky land into soil, which would have released nutrients to flow into those rising oceans. The influx of nutrients into the oceans would have triggered massive algal blooms, which died, decomposed and soaked up oxygen. As they decomposed, the dead algae released hydrogen sulfide, increasing levels of the toxic chemical.

"The oxygen-depleted seas were too much for Devonian marine life. Researchers estimate that 75% of all life went extinct by the end of the Devonian.

***

"The team found evidence of "anoxic events," where waters were completely depleted of oxygen, they reported in the study, published March 8 in the journal Nature(opens in new tab).

"These sharp drops "are likely linked to a series of rapid rises in sea level" due to the melting of South Pole ice sheets during the preceding Silurian period (443.8 million to 419 million years ago), Kaufman said in the statement.

"Simultaneously, plants transformed rocky land into soil, which would have released nutrients to flow into those rising oceans. The influx of nutrients into the oceans would have triggered massive algal blooms, which died, decomposed and soaked up oxygen. As they decomposed, the dead algae released hydrogen sulfide, increasing levels of the toxic chemical.

"The oxygen-depleted seas were too much for Devonian marine life. Researchers estimate that 75% of all life went extinct by the end of the Devonian."

Comment: I do not think God controlled this event but it allowed Him to bring new organisms on the scene.