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End-Triassic extinction
201 million years ago· Extinction or crisis· Earth, climate & extinctions
Well establishedStrong fossil, genetic or geological evidence.
One of the Big Five mass extinctions, about 201 million years ago, which ended the Triassic and cleared the way for dinosaurs.
See it on the Life map →What happened
Estimates vary, from about half to three-quarters of all species. Victims included the last conodonts, many ammonites and reef builders, and on land most crocodile-line archosaurs (phytosaurs, aetosaurs, rauisuchians) and many large amphibians. The cause was the Central Atlantic Magmatic Province (CAMP), vast eruptions that came as Pangaea began to rift. Carbon dioxide and sulfur from the eruptions drove sharp warming, cooling pulses and ocean acidification.
Why it matters
It removed the dinosaurs' main competitors on land, letting them dominate the Jurassic, and reshaped ocean life.
The evidence (fossils, genes, rocks)
Fossil records from many marine and land sites; uranium-lead dates of CAMP lavas in Morocco and North America; carbon isotope shifts; fossil leaf pores recording a rise in carbon dioxide.
Still debated
Why dinosaurs survived when crocodile-line rivals did not is unresolved, and estimates of the extinction's size differ widely.
Connections (4)
▸End-Triassic extinction is one of the Big Five in Extinction & mass extinctionsWell established
The connection
About 201 million years ago, eruptions as the supercontinent Pangaea began to split released carbon and wiped out roughly three-quarters of species, including many crocodile-line reptiles and large amphibians. Dinosaurs survived and soon dominated. It is the fourth of the Big Five and shows how extinctions open opportunities for survivors.
When and how
Central Atlantic Magmatic Province lavas, now found in Morocco, eastern North America and Brazil; boundary section at Kuhjoch, Austria; counted in the 1982 Big Five.
The evidence
Uranium-lead dates show the eruptions and extinction coincide within tens of thousands of years; fossil pollen, footprints and marine fossils record the losses.
Debates and open questions
Some researchers argue its losses were more drawn out than a single mass event; how much it truly cleared the way for dinosaurs is also debated.
▸End-Triassic extinction cleared rivals for DinosaursStrong evidence
The connection
In the late Triassic, dinosaurs shared land with crocodile-line archosaurs such as phytosaurs, aetosaurs and rauisuchians, which were often larger and more varied. The end-Triassic extinction wiped out nearly all of these rivals while dinosaurs came through. In the early Jurassic, dinosaurs moved into the vacated roles and became the dominant large land animals.
When and how
About 201 million years ago, worldwide; well recorded in eastern North America's Newark Basin and in East Greenland.
How sure are we?
Fossils and footprints show crocodile-line groups vanishing at the boundary, while dinosaur footprints become larger and more common just above it.
Debates and open questions
Why dinosaurs survived and rivals did not is unclear: better breathing, insulation against volcanic winters, or simple luck have all been proposed.
▸End-Triassic extinction opened the Jurassic to Sauropods: the long-necked giantsStrong evidence
The connection
With rival large plant-eaters gone, sauropodomorphs expanded. True sauropods appeared in the early Jurassic, and by about 190–180 million years ago they were reaching giant sizes, becoming the main large plant-eaters on land for the rest of the Jurassic.
When and how
Early Jurassic, from about 200 million years ago; early sauropods such as Vulcanodon come from Zimbabwe, with others from elsewhere in Africa and Asia.
How sure are we?
Sauropod bones and wide-gauge footprints become common in early Jurassic rocks, after the extinction removed other large herbivores.
Debates and open questions
Large sauropodomorphs such as Ingentia, about 210 million years old, already existed in the late Triassic, so how much the extinction mattered is debated.
▸Pangaea breaks apart unleashed eruptions that caused End-Triassic extinctionStrong evidence
The connection
As Pangaea began to split along what became the central Atlantic, enormous volumes of magma erupted: the Central Atlantic Magmatic Province. Its carbon dioxide and sulfur gases caused sharp warming, brief cooling pulses and ocean acidification, which drove the extinction.
When and how
Along the rift between eastern North America, northwest Africa, Iberia and northern South America, about 201 million years ago; the lavas now lie on four continents.
How sure are we?
Uranium-lead dates show the earliest lavas coinciding with the extinction, and carbon isotopes and fossil leaf pores record a carbon dioxide spike.
Debates and open questions
Whether the rifting set off the eruptions or a deep mantle plume drove both is debated, as is the relative role of carbon dioxide and sulfur.