Devonian extinction

Devonian extinction
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Name	Devonian extinction
Period	Late Devonian
Time start	~372 Ma
Time end	~359 Ma
Causes	Multiple (anoxia, volcanism, climate change, asteroid hypothesis debated)
Effects	Marine faunal turnovers, reef collapses, vertebrate radiations

Devonian extinction The Late Devonian intervals include a series of major biotic crises that profoundly reshaped marine and early terrestrial ecosystems. Contemporary research links these crises to glaciation events, widespread oceanic anoxia, large igneous province activity, and ecosystem engineering by terrestrial plants; paleontologists, stratigraphers, geochemists, and sedimentologists continue to refine timing and causal links. Major contributors to understanding include workers associated with Geological Society of America, Smithsonian Institution, University of Cambridge, University of Chicago, and international drilling programs such as IODP.

Overview and timeline

The crises occur during the Frasnian and Famennian stages of the Devonian Period, with key horizons centered on the Kellwasser and Hangenberg events recognized in global stratigraphic sections such as those at Kellwasser, Holy Cross Mountains, Miguasha National Park, and the British Isles. Radiometric constraints from U–Pb dating on zircons from volcanic ash beds, biostratigraphy using conodonts and ammonoids, and chemostratigraphy with carbon isotope excursions place major pulses between ~372 Ma and ~359 Ma. Correlation frameworks rely on work by researchers affiliated with the International Commission on Stratigraphy and regional surveys in Euramerica, Gondwana, and Laurentia.

Extinction phases and magnitude

Paleobiological compilations, including datasets from the Paleobiology Database and monographs by teams at the Natural History Museum, London and Royal Ontario Museum, indicate multiple extinction pulses rather than a single instantaneous event. The Frasnian-Famennian Kellwasser pulse eliminated many reef-builders and brachiopod lineages; the later Hangenberg event produced additional losses among vertebrates and ammonoids. Quantitative analyses by paleontologists using diversity curves show genus-level losses comparable to other Phanerozoic crises, with severe declines documented in stromatoporoids, rugose corals, trilobites, and many pelagic invertebrates.

Causes and contributing mechanisms

Investigations integrate evidence from geochemistry, paleobotany, volcanology, and climate modeling conducted at institutions such as ETH Zurich, California Institute of Technology, and University of Tokyo. Widespread marine anoxia is inferred from black shale deposits, elevated organic carbon, and iron speciation signals; these signatures are reported from sections in Spain, Canada, Poland, and China. Episodes of global cooling and glacio-eustasy associated with high-latitude ice sheets are reconstructed using oxygen isotopes and sedimentary facies transitions in Antarctica and Africa. Large igneous province activity, including temporal links to the Viluy Traps and other volcanic centers, provides plausible pulses of CO2 and SO2 perturbation recorded in mercury anomalies and trace-element enrichments. Terrestrial plant expansion, documented by fossil floras in Rhynie chert and coal-bearing sequences, likely altered weathering, nutrient fluxes, and riverine sedimentation, amplifying eutrophication; this mechanism is debated alongside hypotheses invoking bolide impact signatures reported in isolated studies from Poland and Australia.

Biotic impacts and ecological recovery

Marine reef ecosystems, notably stromatoporoid–coral frameworks, collapsed regionally, disrupting habitat for nektonic and benthic faunas documented in museum collections from Muséum national d'Histoire naturelle and the American Museum of Natural History. Placoderms and sarcopterygians experienced turnovers while actinopterygians and early tetrapod lineages radiated during recovery phases recorded in Devonian–Carboniferous boundary strata linked to Greenland and Scotland. Reef recovery during the Carboniferous involved scleractinian successors and microbialites, as recognized in paleontological syntheses by scholars at Yale University and University of Göttingen. Ecosystem engineering by vascular plants precipitated changes in sediment transport and coastal dynamics with long-term effects on benthic communities.

Regional and stratigraphic evidence

High-resolution records derive from classic type sections in Rhenish Massif, Holy Cross Mountains, Frasnes, and North American locales such as Catskill, Michigan Basin, and Miguasha National Park. Geochemical proxies—δ13C excursions, redox-sensitive trace metals, and sulfur isotopes—are instrumental in correlating events across Euramerica, Siberia, and Gondwana basins. Conodont zonation, ammonoid biostratigraphy, and benthic foraminiferal turnovers underpin regional chronologies used by stratigraphers working with the International Union of Geological Sciences. Core records from ODP and IODP expeditions provide open-ocean perspectives complementing shallow-marine outcrop studies.

Research history and debates

Early recognition of Late Devonian crises emerged from 19th-century stratigraphic work in the United Kingdom and continental Europe; modern syntheses owe much to investigators at University of Leicester, University of Birmingham, and University of Kansas. Debates continue over the relative weights of anoxia, volcanism, climate change, and biotic feedbacks, with interdisciplinary contributions from teams at Stanford University, Massachusetts Institute of Technology, and University of California, Berkeley. New approaches—high-precision geochronology, compound-specific isotope analysis, and basin-scale climate modeling—are deployed by consortia including NSF-funded projects and international drilling initiatives to resolve timing and mechanisms. The field remains dynamic, with ongoing discoveries in remote sections of China, Australia, and South America reshaping interpretations.

Category:Extinction events