<P> The Late Devonian extinction was one of five major extinction events in the history of the Earth's biota . A major extinction, the Kellwasser event, occurred at the boundary that marks the beginning of the last phase of the Devonian period, the Famennian faunal stage (the Frasnian--Famennian boundary), about 375--360 million years ago . Overall, 19% of all families and 50% of all genera became extinct . A second, distinct mass extinction, the Hangenberg event, closed the Devonian period . </P> <P> Although it is clear a massive loss of biodiversity occurred in the Later Devonian, the extent of time during which these events took place is uncertain, with estimates ranging from 500,000 to 25 million years, extending from the mid-Givetian to the end - Famennian . Nor is it clear whether it concerned two sharp mass extinctions or a series of smaller extinctions, though the latest research suggests multiple causes and a series of distinct extinction pulses through an interval of some three million years . Some consider the extinction to be as many as seven distinct events, spread over about 25 million years, with notable extinctions at the ends of the Givetian, Frasnian, and Famennian stages . </P>

What organisms were dominant after the devonian mass extinction