Extinction: Late Devonian Mass Extinction

Abstract

Abstract The Late Devonian mass extinction, which occurred 371.9 million years ago (Ma), is one of the ‘Big Five’ mass extinctions in Earth history. Suggested main proximate causes of the crisis include oceanic anoxia and climate swings. The severe loss of biodiversity affected both marine and terrestrial ecosystems and animal (especially metazoan reefs) and plant communities. Both high‐ and low‐temperature stresses due to rapid climate switches and oxygen deprivation due to anoxia have been implicated as kill mechanisms in the mass extinction. The ultimate trigger for these kill mechanisms is still conjectural, but a crucial role of Eovariscan tectono‐volcanic events has recently been highlighted, coupled with episodic expansion of terrestrial vegetation due to greenhouse effect driven by magmatic outgassing. Oceanic anoxia may have been triggered by the land‐derived nutrification pulses. Postulated triggers of global cooling include the lag‐time volcanic winter but superimposed on atmospheric carbon dioxide downdraw due to biological and tectonic factors and chemical weathering of terrestrial rocks. Key Concepts Early lobe‐finned fishes and tetrapod (four‐limbed) vertebrates were severely impacted by the Late Devonian mass extinction. The destruction of Devonian‐style metazoan reefs triggered a permanent change in global marine ecosystems. Both oscillating temperature stress (from hyperthermia to hypothermia) and oxygen deprivation (hypoxia) are implicated in the Late Devonian mass extinction. Catastrophic mantle plume and arc volcanism is debated as a main trigger of the Late Devonian mass extinction. Bolide impact (in ocean?) can only be seen as an additional source of stresses in the global ecosystem.