Late Devonian extinction

The Late Devonian extinction was a series of extinction events in the Late Devonian Epoch that combined constituted one of the five biggest mass extinction events in Earth's history. The phrase largely alludes to the Kellwasser event (also known as the Frasnian-Famennian extinction), which happened about 372 million years ago at the border between the Frasnian and Famennian stages of the Devonian Period. 19% of all families and 50% of all genera went extinct. The Hangenberg event (also known as the end-Devonian extinction) happened 359 million years ago, putting the Famennian and Devonian periods to a close as the Earth entered the Carboniferous Period.

Plants and insects had populated the region by the Late Devonian. Corals and stromatoporoids developed huge reefs in the oceans. Euramerica and Gondwana were merging into what would become Pangaea. Only marine life appears to have been harmed by the extinction. Brachiopods, trilobites, and reef-building species were particularly hard struck, with the last virtually totally disappearing. The reasons of these extinctions remain unknown. Changes in sea level and ocean anoxia, presumably caused by global cooling or marine volcanism, are among the leading possibilities.

The impact of a comet or similar extraterrestrial body, such as the Siljan Ring occurrence in Sweden, has also been proposed. According to some statistical research, the decline in variety was driven more by a fall in speciation than an increase in extinctions. Rather than a single event, this might have been triggered by invasions of cosmopolitan species. Placoderms were severely harmed by the Kellwasser event and nearly extinct during the Hangenberg event, although most other jawed vertebrates were less severely afflicted. Agnathans (jawless fish) were in decline long before the end of the Frasnian, and the extinctions nearly wiped them off.