The Permian-Triassic Extinction: The Biggest Mass Extinction in Earth's History

The Permian-Triassic extinction killed about 90% of all marine species and 70% of all land vertebrates around 252 million years ago. It is the largest known mass extinction in Earth's history — bigger than the asteroid impact that killed the dinosaurs 186 million years later. The event reshaped life on Earth completely, and the slow recovery in its aftermath set the stage for the rise of the dinosaurs. This guide covers what scientists know about the Permian-Triassic boundary, what caused it, and what came next.

The short answer#

About 252 million years ago, a combination of massive volcanic eruptions (the Siberian Traps), runaway climate change, and ocean acidification killed 90% of all species on Earth. It is the most devastating extinction event in Earth's history. The recovery took 10 million years. The survivors and their descendants eventually became the dinosaurs, mammals, and other groups that dominated the Mesozoic Era.

What happened#

The end of the Permian Period was the largest crisis in life's history. Multiple factors converged.

The Siberian Traps#

A massive volcanic event in what is now Siberia released huge amounts of lava, gases, and dust into the atmosphere over about a million years. The volcanic activity covered an area the size of Western Europe.

Effects:

• Massive CO2 release — atmospheric carbon dioxide spiked
• Sulfur dioxide release — created acid rain globally
• Coal seam ignition — when the lava hit ancient coal deposits, it burned them, releasing more carbon

Runaway climate change#

The CO2 spike triggered:

• Global warming — ocean and atmospheric temperatures rose dramatically
• Ocean acidification — CO2 dissolves in ocean water, forming acid
• Ocean oxygen depletion — warmer water holds less oxygen
• Methane release — frozen methane in ocean floor melted, accelerating warming

Ocean ecosystem collapse#

The combined effects (warmer, more acidic, less oxygen) killed marine life on a massive scale. About 90% of marine species disappeared:

• Trilobites (a class of arthropods that had dominated oceans for 270 million years) — fully extinct
• Most coral species — wiped out
• Brachiopods — devastated
• Most fish lineages — drastically reduced

Land ecosystem collapse#

About 70% of land vertebrates went extinct. The atmosphere got hostile enough that even land animals struggled:

• Most amphibian families — drastically reduced
• Most reptile groups — devastated
• Most early mammal-like reptiles — wiped out, with a few survivors

How we know#

Five lines of evidence.

1. Sudden fossil drop#

In rock layers worldwide, the Permian-Triassic boundary shows a dramatic drop in fossil diversity. Below the boundary: rich Permian ecosystems. Above the boundary: very few species, mostly opportunistic survivors. The boundary is geologically thin — the extinction was relatively sudden by geological standards.

2. Carbon isotope shifts#

Carbon isotope ratios in the boundary rocks show a sudden change consistent with massive carbon release into the atmosphere.

3. Siberian Trap dating#

Radioactive dating of the Siberian Trap volcanic rocks shows they erupted at exactly the time of the extinction — around 252 million years ago.

4. Ocean acidification evidence#

Marine fossil shells from the period show chemistry changes consistent with severe ocean acidification.

5. Plant fossil evidence#

Pollen and plant fossil records show massive land plant die-offs at the same boundary.

When all five lines converge on the same time and the same cause, the picture becomes clear.

The recovery#

The recovery from the Permian-Triassic extinction took about 10 million years. During the Early Triassic Period:

• Marine ecosystems were dominated by a few opportunistic species (some bivalves, some brachiopods)
• Land ecosystems were dominated by survivors like Lystrosaurus (a small herbivorous mammal-like reptile)
• Climate stayed unstable for millions of years
• Coral reefs were absent for several million years
• Insect diversity dropped dramatically and slowly recovered

Lystrosaurus dominates#

For a while in the Early Triassic, Lystrosaurus was so common that some scientists call this period the "Lystrosaurus zone." It was one of the most widespread land vertebrates that ever lived — found on every continent — partly because it was one of the few large land animals to survive.

The first dinosaurs appear#

About 230 million years ago, in the Middle Triassic (22 million years after the extinction), the first true dinosaurs appeared. They were small, generalist, and slowly diversifying in a world still recovering. By the Late Triassic, dinosaurs had become a significant land animal group. The full story is in our Mesozoic Era explained post.

Why the Permian-Triassic matters#

This extinction event shaped everything that came after.

Cleared the way for dinosaurs#

Without the Permian-Triassic extinction, the dinosaur lineage might never have dominated. The earlier reptile groups that had been dominant (the synapsids, including ancestors of mammals) were drastically reduced. The archosaurs (the lineage that included dinosaurs) survived in greater numbers and diversified into the vacated niches.

Showed how fragile ecosystems are#

The Permian-Triassic is a warning. Massive volcanic activity caused climate change that drove the extinction. Modern researchers studying climate change cite the Permian-Triassic as an example of what can happen when CO2 levels rise too fast.

Took 10 million years to recover#

Even after the immediate cause stopped (the volcanic activity gradually subsided), ecosystems took 10 million years to recover their previous diversity. Major extinctions reshape life on a geological time scale.

Compared to other mass extinctions#

There have been five major mass extinctions in Earth's history. The Permian-Triassic is the biggest.

Extinction	When	What was lost
Ordovician-Silurian	444 million years ago	~85% of species
Late Devonian	372 million years ago	~75% of species
Permian-Triassic	252 million years ago	~90% of marine, ~70% of land
Triassic-Jurassic	201 million years ago	~80% of species
Cretaceous-Paleogene (killed dinosaurs)	66 million years ago	~75% of species

Some scientists argue we are currently in a "sixth extinction" driven by human activity, with biodiversity declining at rates approaching the major past extinctions.

At a Jurassic Petting Zoo event#

For schools running paleontology, geology, or environmental science units, the Permian-Triassic extinction is one of the most important events to understand. It set the stage for the dinosaur era and shows how dramatic climate change can reshape life on Earth. Rangers at our school events can integrate mass extinction content into the educational portion on request.

Frequently asked questions#

Was the Permian-Triassic the asteroid extinction?#

No. That's a common confusion. The Cretaceous-Paleogene extinction (66 million years ago, the one that killed dinosaurs) was the asteroid impact. The Permian-Triassic was caused by massive volcanic eruptions, not an asteroid.

Could a Permian-Triassic-scale event happen again?#

In theory, yes — large volcanic events have happened multiple times in Earth's history. Whether modern human activity could trigger similar climate change is the subject of active research. The geological time scale of the Permian-Triassic was very long (millions of years for the worst effects); modern climate change is happening much faster.

How do we know what species existed before the Permian-Triassic?#

Through fossils preserved in Permian-age rocks worldwide. The pre-extinction Permian Period had rich ecosystems, well-documented in places like Texas (where many Permian fossils are found), Africa, China, and Russia.

Was Florida around then?#

Florida did not yet exist as land during the Permian. The future state was part of the continental shelf, underwater. Florida's emergence as land happened much later, during the Cenozoic Era. See our Florida's prehistoric past for the local geological timeline.

What's the connection between the Permian-Triassic extinction and modern climate change?#

Both involve major CO2 increase and climate disruption. The Permian-Triassic teaches that rapid climate change can be catastrophic for biodiversity. Researchers studying modern climate use the Permian-Triassic as one historical reference point.

Did any dinosaurs survive the Permian-Triassic extinction?#

No. Dinosaurs didn't exist yet at the time of the Permian-Triassic. They first appeared about 230 million years ago, 22 million years after the extinction. The Permian-Triassic killed the dominant animal groups of its era and cleared the way for dinosaurs to eventually evolve and rise.

Explore deep time#

For South Florida schools and families exploring Earth's history and the events that shaped life on the planet, our school events and birthdays include content about geological time and major extinctions. Check date availability.