The Devonian extinction
The reefs collapse — and trees may be to blame
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The extinction consists of several pulses, of which the Kellwasser event at 372 million years and the Hangenberg at 359 are the most severe. It hit marine life far harder than terrestrial, and reef-building organisms almost completely — the stromatoporoid reefs never returned. The best-supported explanation is eutrophication and anoxia driven by weathering and nutrient runoff from the new forests, combined with rapid cooling. It is thus the second of two mass extinctions in which the rise of land plants is the prime suspect.
For children
The world's reefs, which had grown for a hundred million years, almost entirely vanished. The sea became oxygen-poor and choked with algae. One of the likeliest explanations is uncomfortable: the new forests on land washed so much nutrient into the ocean that it suffocated life there.
Connects to
Part of Terra Saga — the story of Earth on a timeline. terrasaga.org