What were the Devonian extinctions?

The Devonian extinctions were a series of mass extinction events that occurred during the Devonian Period (419.2 million to 359 million years ago), primarily impacting marine life. These extinctions, including the Lower Zilchov , Taghanic , Kellwasser , and Hangenberg events, resulted in the elimination of 70 to 80 percent of all animal species and about 20 percent of animal families of the time. The causes of these events are still debated, but contributing factors may include excessive sedimentation , rapid global warming or cooling , meteorite impacts , and significant nutrient runoff from the continents. Some researchers link the extinctions to layers of black shale, indicative of low oxygen conditions, resulting from high global temperatures slowing the mixing rate between the ocean’s surface and deeper layers.

When did the Devonian extinctions happen?

The Devonian extinctions, a series of mass extinction events, occurred throughout the Devonian Period (419.2 million to 359 million years ago). The Kellwasser Event occurred about 372.2 million years ago. The Siljan structure in Sweden, an impact crater, has been dated to approximately 377 million years ago. The Hangenberg Event happened at the end of the Famennian Stage. These extinctions primarily affected marine communities and eliminated 70 to 80 percent of all animal species and roughly 20 percent of animal families. The causes may be from a combination of stresses, such as meteorite impacts, global warming or cooling, or excessive sedimentation.

What kinds of life were affected during the Devonian extinctions?

The Devonian extinctions, a series of events that primarily impacted marine life, led to the elimination of 70 to 80 percent of all animal species and roughly 20 percent of animal families of the time. During the Devonian Period, marine invertebrates were varied, and most shallow and deep marine ecological niches were exploited. The extinction events eliminated graptoloids, goniatites, corals, brachiopods, conodont species, trilobites, and clymeniids.

What do scientists think caused the Devonian extinctions?

The Devonian extinctions, a series of events that primarily impacted marine life, occurred during the Devonian Period. While the exact causes are still debated, scientists believe that a combination of factors contributed to these extinctions, including excessive sedimentation , rapid global warming or cooling , meteorite impacts , and massive nutrient runoff from the continents. During the Devonian, there were periods of widespread hypoxic or anoxic sedimentation , which indicates that there was little to no oxygen in the Devonian seas. Some of these successions are associated with significant extinction episodes.

How did the Devonian extinctions affect ocean life and ecosystems?

The Devonian extinctions, a series of events that primarily impacted marine life, led to the disappearance of 70 to 80 percent of all animal species and about 20 percent of animal families during the Devonian Period. These extinctions significantly altered marine ecosystems, eliminating many species and creating opportunities for others. The events included the extinction of graptoloids, goniatites, corals, brachiopods, trilobites, and conodont species. The causes were varied and possibly included widespread anoxic conditions, bolide impacts, global warming or cooling, and nutrient runoff. These factors led to habitat loss and reduced oxygen levels, which many marine species could not survive.

Why are the Devonian extinctions important for understanding Earth's history?

The Devonian extinctions, a series of events that occurred during the Devonian Period, are important for understanding Earth's history because they significantly impacted marine life and altered the course of evolution. These extinctions, which include the Lower Zilchov, Taghanic, Kellwasser, and Hangenberg events, eliminated 70 to 80 percent of all animal species and about 20 percent of animal families. The Devonian series of extinctions are linked to several stresses, such as sedimentation , global warming or cooling, meteorite impacts , and nutrient runoff . They provide insights into how environmental changes can trigger widespread loss of biodiversity. Studying these extinctions helps scientists understand the potential consequences of current environmental challenges.

Devonian extinctions

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Line graph showing the number of marine animal families from the Precambrian era to the present, with illustrations of key groups such as trilobites, ammonoids, marine reptiles, and diatoms. The graph highlights major extinction events and a rise to 1,900 living families today.

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marine family diversity The diversity of marine animal families since late Precambrian time. The data for the curve comprise only those families that are reliably preserved in the fossil record; the 1,900 value for living families also includes those families rarely preserved as fossils. The several pronounced dips in the curve correspond to major mass-extinction events. The most catastrophic extinction took place at the end of the Permian Period.

Devonian extinctions

series of mass extinctions

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Michael R. House

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Top Questions

What were the Devonian extinctions?
The Devonian extinctions were a series of mass extinction events that occurred during the Devonian Period (419.2 million to 359 million years ago), primarily impacting marine life. These extinctions, including the Lower Zilchov, Taghanic, Kellwasser, and Hangenberg events, resulted in the elimination of 70 to 80 percent of all animal species and about 20 percent of animal families of the time.

The causes of these events are still debated, but contributing factors may include excessive sedimentation, rapid global warming or cooling, meteorite impacts, and significant nutrient runoff from the continents. Some researchers link the extinctions to layers of black shale, indicative of low oxygen conditions, resulting from high global temperatures slowing the mixing rate between the ocean’s surface and deeper layers.
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Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
When did the Devonian extinctions happen?
The Devonian extinctions, a series of mass extinction events, occurred throughout the Devonian Period (419.2 million to 359 million years ago). The Kellwasser Event occurred about 372.2 million years ago. The Siljan structure in Sweden, an impact crater, has been dated to approximately 377 million years ago. The Hangenberg Event happened at the end of the Famennian Stage.

These extinctions primarily affected marine communities and eliminated 70 to 80 percent of all animal species and roughly 20 percent of animal families. The causes may be from a combination of stresses, such as meteorite impacts, global warming or cooling, or excessive sedimentation.
3 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
What kinds of life were affected during the Devonian extinctions?
The Devonian extinctions, a series of events that primarily impacted marine life, led to the elimination of 70 to 80 percent of all animal species and roughly 20 percent of animal families of the time.

During the Devonian Period, marine invertebrates were varied, and most shallow and deep marine ecological niches were exploited. The extinction events eliminated graptoloids, goniatites, corals, brachiopods, conodont species, trilobites, and clymeniids.
2 Britannica Sources
1. Devonian extinctions
2. Devonian Period: Extinction events
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
What do scientists think caused the Devonian extinctions?
The Devonian extinctions, a series of events that primarily impacted marine life, occurred during the Devonian Period. While the exact causes are still debated, scientists believe that a combination of factors contributed to these extinctions, including excessive sedimentation, rapid global warming or cooling, meteorite impacts, and massive nutrient runoff from the continents.

During the Devonian, there were periods of widespread hypoxic or anoxic sedimentation, which indicates that there was little to no oxygen in the Devonian seas. Some of these successions are associated with significant extinction episodes.
3 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
How did the Devonian extinctions affect ocean life and ecosystems?
The Devonian extinctions, a series of events that primarily impacted marine life, led to the disappearance of 70 to 80 percent of all animal species and about 20 percent of animal families during the Devonian Period.

These extinctions significantly altered marine ecosystems, eliminating many species and creating opportunities for others. The events included the extinction of graptoloids, goniatites, corals, brachiopods, trilobites, and conodont species. The causes were varied and possibly included widespread anoxic conditions, bolide impacts, global warming or cooling, and nutrient runoff. These factors led to habitat loss and reduced oxygen levels, which many marine species could not survive.
4 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
Why are the Devonian extinctions important for understanding Earth's history?
The Devonian extinctions, a series of events that occurred during the Devonian Period, are important for understanding Earth's history because they significantly impacted marine life and altered the course of evolution. These extinctions, which include the Lower Zilchov, Taghanic, Kellwasser, and Hangenberg events, eliminated 70 to 80 percent of all animal species and about 20 percent of animal families.

The Devonian series of extinctions are linked to several stresses, such as sedimentation, global warming or cooling, meteorite impacts, and nutrient runoff. They provide insights into how environmental changes can trigger widespread loss of biodiversity. Studying these extinctions helps scientists understand the potential consequences of current environmental challenges.
3 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Devonian extinctions, a series of mass extinction events primarily affecting the marine communities of the Devonian Period (419.2 million to 359 million years ago). At present it is not possible to connect this series definitively with any single cause. It is probable that they may record a combination of several stresses—such as excessive sedimentation, rapid global warming or cooling, bolide (meteorite or comet) impacts, or massive nutrient runoff from the continents. Collectively, the extinctions (which include the Lower Zilchov, Taghanic, Kellwasser, and Hangenberg events) are responsible for the elimination of 70 to 80 percent of all animal species present during the Devonian and about 20 percent of families of Devonian animals. However, the series ranks lowest in severity of the five major extinction episodes that span geologic time.

(Read E.O. Wilson’s Britannica essay on mass extinction.)

Throughout the Devonian there were periods of widespread hypoxic or anoxic sedimentation (that is, sedimentary events occurred that indicated little free oxygen or no oxygen at all was dissolved in Devonian seas). Some of these are known to be periods of significant extinction, and all are associated with some faunal anomaly in marine strata. These events are named according to the taxa involved. Some are associated with very wide distribution of certain taxa, such as the Monograptus uniformis, Pinacites jugleri, and Platyclymenia annulata. The Lower Zlichov Event, which occurred at the beginning of the Emsian Stage about 407.6 million years ago, is associated with the extinction of the graptoloids (a type of graptolite) and the appearance of the coiled cephalopod goniatites. Three events are very significant extinction episodes: the Taghanic Event, which formerly was used to draw the boundary between the Middle and Upper Devonian, was a marked period of extinction for goniatites, corals, and brachiopods; the Kellwasser Event saw the extinction of the beloceratid and manticoceratid goniatite groups, many conodont species, most colonial corals, several groups of trilobites, and the atrypid and pentamerid brachiopods at the Frasnian-Famennian boundary (about 372.2 million years ago); and the Hangenberg Event saw the extinction of phacopid trilobites, several groups of goniatites, and the unusual Late Devonian coiled cephalopods, the clymeniids, at the end of the Famennian Stage.

Earlier, certain writers sought to link these events with thin layers of iridium, characteristic of meteorite or bolide impacts. Evidence of a bolide impact, in the form of possible impact ejecta, has been reported in Middle Devonian deposits and is associated with a pulse of extinction. The Siljan structure in Sweden, an impact crater about 65 km (about 40 miles) in diameter, has been dated to approximately 377 million years ago. This places the impact within the error range for the estimated boundary between the Frasnian-Famennian stages and also within the Kellwasser extinction. Nevertheless, the connection between this impact and the Kellwasser Event is still being debated.

A stronger environmental link to Devonian extinctions involves the layers of black shale characteristic of low oxygen conditions. Environmental stress is thought to have taken place when high global temperatures slowed the mixing rate between the ocean’s surface and deeper layers. Bottom waters experienced a lowered reoxygenation rate, which may have resulted in the extinction of many marine species. It is still debated whether these events were caused by climatic extremes caused by an increase in the amount of solar energy, by an amplified greenhouse effect, or by processes wholly confined to Earth. For example, greater production of organic matter, perhaps owing to an increased influx of nutrients related to the colonization of landmasses by rooted plants, may have made continental seas more susceptible to anoxia.

There is also evidence that extinctions may be associated with rapid global warming or cooling. Particularly in the Late Devonian, extinction events may relate to periods of abrupt cooling associated with the development of glaciers and the substantial lowering of sea level. It has been argued that patterns of faunal change at the Kellwasser Event are consistent with global cooling.

Michael R. House

Devonian extinctions

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