Late Devonian mass extinction

A prolonged biodiversity crisis in the Late Devonian, marked by major marine losses during the Kellwasser and Hangenberg events. It disproportionately affected reef ecosystems and many marine groups.

Ocean anoxia: A condition in which ocean water contains little or no dissolved oxygen. Oxygen-poor waters spread across parts of the Devonian seafloor during extinction intervals.
Kellwasser event: A major Late Devonian extinction interval associated with widespread marine anoxia, around the Frasnian–Famennian boundary. It marks the best-known early pulse of the broader Devonian biodiversity crisis.
Devonian: A geological period from about 419 to 359 million years ago, known for major changes in marine and terrestrial life. The extinction spans the period's later stages and precedes the Carboniferous.
Stromatoporoid: An extinct group of sponge-like organisms that built major Paleozoic reefs. Their decline helped bring the Devonian's large reef systems to an end.
Land plant evolution: The evolutionary history and diversification of plants on land. Expanding forests may have altered weathering, nutrient delivery, and carbon storage before the marine crises.
Eutrophication: The enrichment of water with nutrients that can fuel excessive biological growth and oxygen depletion. Nutrient runoff from expanding land plants may have helped drive oxygen loss in Devonian seas.
Hangenberg event: A major extinction interval near the Devonian–Carboniferous boundary, associated with environmental and sea-level change. It represents a later pulse that further transformed marine and terrestrial ecosystems.
Frasnian: The penultimate stage of the Devonian Period, preceding the Famennian. The first major extinction pulse occurred near the end of this stage.
Rugose coral: An extinct group of corals, including solitary and colonial forms, common in Paleozoic seas. Rugose corals were among the reef builders sharply reduced by the crisis.
Devonian forest: Early forests that spread across land during the Devonian, including tree-sized plants. Their growth is implicated in competing explanations for nutrient runoff and long-term carbon change.

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