---
title: "Late Devonian Extinction | General Biology I"
description: "Late Devonian extinction is a late Paleozoic mass extinction that wiped out most marine species and reshaped animal evolution in General Biology I."
canonical: "https://fiveable.me/college-bio/key-terms/late-devonian-extinction"
type: "key-term"
subject: "General Biology I"
unit: "Unit 47"
---

# Late Devonian Extinction | General Biology I

## Definition

The Late Devonian extinction was a long mass extinction in the Devonian Period that eliminated much of the ocean life in General Biology I. It is known for major losses in reef communities and armored fishes.

## What It Is

The Late Devonian extinction is a major mass extinction event in General Biology I that happened near the end of the Devonian Period, roughly 375 to 360 million years ago. It did not happen all at once. Instead, it unfolded as a series of losses over several million years, with two especially severe pulses that hit marine life hard.

If you are seeing this term in a biology unit on animal evolution, think of it as a reset in ocean ecosystems. Many Devonian seas were dominated by placoderms, early reef builders, and other marine groups that had flourished for millions of years. During the extinction, a large share of those species disappeared, including about 75% of marine species overall in many summaries of the event.

The exact cause is still debated, and that is part of what makes this event useful in biology. Scientists usually point to a mix of factors rather than one single trigger. Changes in climate, drops in oxygen in seawater, and possible asteroid impacts are all discussed as contributors. If ocean circulation changed, shallow seas and reef habitats could have become unstable, which would be especially bad for organisms that depended on well-oxygenated water and stable coastal environments.

A big idea here is that mass extinctions are not just losses, they also change which lineages get the next chance to diversify. After the Late Devonian extinction, the balance of marine life shifted. Armored fishes and some reef communities declined, while later groups such as bony fishes became more prominent. That shift matters because it shows how evolution is shaped by both adaptation and ecological opening, when empty niches allow new groups to expand.

For General Biology I, this term usually shows up as part of the broader story of animal evolution and biodiversity over time. It connects the Devonian world to the Carboniferous world that followed, where new ecosystems developed after the extinction pressure had already changed the rules.

## Why It Matters

The Late Devonian extinction matters in General Biology I because it is a clear example of how environmental change can redirect evolution on a massive scale. Instead of thinking of evolution as a smooth upward path, this event shows you a world where biodiversity can crash, then recover in a different form.

It also gives you a way to connect fossils, ecology, and evolution in one timeline. If a quiz asks why certain groups disappear from the fossil record, or why later animals become more common, this extinction is part of the explanation. It helps you interpret why marine dominance shifted away from some ancient fish groups and reef systems toward other lineages in later periods.

The term also shows up when you compare mass extinctions. Biology courses often use extinction events to show that Earth's history includes repeated ecosystem turnovers, not just the rise of new species. The Late Devonian extinction sits between earlier diversification events and later extinction events, so it helps you place animal evolution in sequence instead of treating each group as if it appeared in isolation.

Finally, it is a reminder that cause and effect in biology are often layered. Climate, oxygen availability, habitat structure, and evolutionary competition can all interact. That makes this term a good fit for questions that ask you to explain patterns in biodiversity rather than just name a date.

## Connections

### Mass extinction

The Late Devonian extinction is one example of a mass extinction, meaning a large fraction of species disappear in a relatively short geologic window. In biology, that label matters because it signals ecological disruption, not just normal background extinction. Comparing this event to other mass extinctions helps you see patterns in why major groups vanish and how ecosystems recover afterward.

### Devonian Period

This extinction happened during the Devonian Period, so the timing matters. The Devonian is often associated with major changes in marine life and the early history of vertebrates. When you place the extinction inside that period, you can connect it to what came before and after, especially the shift from Devonian marine communities to later Paleozoic ecosystems.

### [End-Permian extinction](/college-bio/key-terms/end-permian-extinction)

The End-Permian extinction is another mass extinction, but it is even more severe than the Late Devonian event. Comparing them helps you separate the idea of extinction pattern from extinction scale. In class, that comparison can come up when you are asked which event caused the biggest biodiversity loss or which ecosystems were most affected.

### Biodiversity

The Late Devonian extinction is a direct example of biodiversity loss. It reduced the number of species in marine ecosystems and changed which groups dominated the oceans. That makes it useful when you are tracing how biodiversity rises and falls over geologic time, especially when environmental stress removes many species at once.

## On the AP Exam

A quiz item on this term usually asks you to identify it as a mass extinction in the Devonian and explain what was lost, especially marine species and reef communities. If you get a timeline question, place it before the Carboniferous and after the Devonian's marine diversification. If you see a fossil or ecosystem prompt, look for evidence of a shift away from placoderms and reef builders. In short-answer or essay questions, connect the extinction to environmental stress such as anoxia or climate change and then explain how the loss opened ecological space for later groups. If your instructor uses case studies, this term may also appear in a comparison with other extinction events, where you describe similarities in cause, scale, or recovery.

## late Devonian extinction vs End-Permian extinction

These are both mass extinctions, but they are not the same event. The Late Devonian extinction happened much earlier and mostly reshaped marine ecosystems, while the End-Permian extinction came later and caused the largest known biodiversity loss in Earth's history. If you mix them up, check the date and the organisms most affected.

## Key Takeaways

- The Late Devonian extinction was a prolonged mass extinction near the end of the Devonian Period, not a single sudden disaster.
- It caused major losses in marine life, including reef communities and placoderm fishes that had been common in Devonian seas.
- Scientists still debate the cause, but climate change, low oxygen in the oceans, and possible impacts are all part of the discussion.
- The event matters because it changed which groups dominated marine ecosystems and opened room for later evolutionary expansion.
- In General Biology I, this term is mainly about extinction patterns, biodiversity loss, and how evolution responds after ecological collapse.

## FAQs

### What is the Late Devonian extinction in General Biology I?

It is a mass extinction that happened near the end of the Devonian Period and removed a large share of marine species. In biology classes, it is usually used to show how environmental change can restructure ecosystems and shift which organisms dominate the oceans.

### What caused the Late Devonian extinction?

There is no single settled cause. The main ideas include climate change, oxygen-poor oceans, changes in sea level or ocean circulation, and possibly asteroid impacts. Most biology explanations treat it as a mix of stressors that made marine ecosystems unstable.

### What organisms were affected most by the Late Devonian extinction?

Marine organisms were hit hardest, especially reef builders and placoderm fishes. Because many Devonian ecosystems depended on stable shallow seas and oxygen-rich water, those habitats were especially vulnerable when conditions changed.

### How is the Late Devonian extinction different from the End-Permian extinction?

Both are mass extinctions, but the End-Permian extinction was later and far more severe. The Late Devonian event mainly reshaped marine life over several pulses, while the End-Permian wiped out an even larger fraction of Earth's species across land and sea.

## Related Study Guides

- [47.1 The Biodiversity Crisis](/college-bio/unit-47/1-biodiversity-crisis/study-guide/Ui7PhWJQN73iX40M)

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