History › Complex life › Age of dinosaurs
Permian extinction ('the Great Dying')
c. 252 million years ago· Event· Life & early humans
Well documentedSolid records, physical evidence or scientific consensus.
The worst mass extinction in Earth's history, about 252 million years ago, killed an estimated 80–90 percent of sea species.
See it on the History map →What happened
Enormous volcanic eruptions in Siberia, the Siberian Traps, released vast amounts of carbon dioxide, partly by baking buried coal and other carbon-rich rock. The planet warmed by roughly 10°C (18°F); oceans turned acidic and lost oxygen. Reefs collapsed, trilobites vanished for good, and perhaps 70 percent of land vertebrate species died out; estimates vary. Recovery took millions of years. The Curious Life map goes deeper.
Why it matters
It reset life on Earth, ending the reign of the mammals' early relatives and opening the way for dinosaurs.
How we know
Precise dating of Siberian lava and of rock layers at Meishan, China, shows the eruptions and die-off overlapped; fossils record the abrupt losses; rock chemistry records warming and oxygen loss.
Still debated
Exactly how fast the die-off happened, and which killer (heat, acid or lack of oxygen) did the most damage, are still debated.
Connections (3)
▸Permian extinction ('the Great Dying') struck life across Supercontinent PangaeaWell documented
The connection
The Great Dying struck while nearly all land was joined in Pangaea. With a single landmass and one world ocean, the warming, acidifying seas and loss of oxygen reached almost everywhere, possibly leaving few refuges. Life across Pangaea collapsed, on land and at sea.
When and how
Across the supercontinent and its surrounding ocean, about 252 million years ago.
How we know
Rock layers in China, Russia, South Africa and Antarctica, all once part of Pangaea, record the same abrupt extinction.
Debates and open questions
Whether Pangaea's single-block shape made the extinction worse, by limiting refuges or slowing ocean circulation, is debated.
▸Permian extinction ('the Great Dying') cleared the way for Age of dinosaursWell documented
The connection
By wiping out most land animals, including the dominant mammal relatives, the Great Dying left empty roles in nature. In the recovery, reptile groups diversified rapidly, and dinosaurs appeared about 20 million years later. A second extinction about 201 million years ago then let them dominate.
When and how
Worldwide, during the Triassic Period, between about 252 and 201 million years ago.
How we know
Fossils show mammal relatives declining after the extinction while reptile groups, including dinosaur ancestors, spread.
Debates and open questions
Dinosaurs took millions of years to rise; how much that owed to the Great Dying versus later climate shifts is debated.
▸Human-caused climate change risks echoing the warming behind the Permian extinction ('the Great Dying')Debated
The connection
The Great Dying was driven by a huge release of carbon dioxide that warmed the planet and acidified the oceans. Today's emissions are far smaller in total so far, but are being added at a rate that may exceed the Permian's. Scientists study the Permian as a worst-case example of what rapid carbon release can do.
When and how
The Permian event: Siberia, about 252 million years ago. Today: worldwide since the 1800s, as people burn coal, oil and gas.
How sure are we?
Permian rocks record warming, ocean acidification and oxygen loss; similar trends are measured today. The comparison is an analogy, not a prediction.
Debates and open questions
How close the parallel is remains argued: today's warming is far smaller so far, and whether ecosystems could pass similar tipping points is uncertain.