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☄️ Earth's Mass Extinctions

Five times in Earth's long history, life was nearly wiped out. Meet the Big Five mass extinctions, from the icy end-Ordovician to the asteroid that ended the dinosaurs, and see how the planet recovered each time.

lessons

~20 min

to learn

🔬 Science

subject

Teens

level

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What you’ll learn

When Life Nearly EndedDefine a mass extinction and understand how fossils in rock layers reveal these ancient disasters.A mass extinction is when a huge share of Earth's species die out worldwide in a short time, far above the normal rate. Geologists recognize them when many fossils vanish together across the world. Five such events, the Big Five, struck over the last 500 million years.
The Big Five DisastersDescribe the causes of the end-Ordovician, Late Devonian, end-Permian, and end-Triassic extinctions.The end-Ordovician was driven by an ice age and falling seas; the Late Devonian by oxygen-starved oceans. The end-Permian Great Dying, caused by vast Siberian eruptions, warming, and acid oceans, was the worst of all. The end-Triassic, driven by more volcanism, cleared the way for the dinosaurs.
Asteroid and AftermathExplain the end-Cretaceous impact and compare the severity of all five extinctions.About 66 million years ago an asteroid struck near modern Mexico, darkening the sky and collapsing food chains, ending the non-avian dinosaurs. Comparing the Big Five, the end-Permian was the most severe. After each event, life recovered in new forms, eventually including mammals and us.

Questions this course answers

What makes an event a mass extinction rather than ordinary extinction?

A mass extinction is when a huge share of Earth's species vanish worldwide in a short slice of geological time.

How do geologists recognize a mass extinction in the rocks?

When many fossils that were common suddenly vanish in the layers above, it marks an extinction event.

What mainly drove the end-Ordovician extinction about 444 million years ago?

A harsh ice age locked up water and dropped sea levels, destroying the shallow seas where most life lived.

Why is the end-Permian extinction nicknamed the Great Dying?

The end-Permian was the deadliest event ever, wiping out the vast majority of species on land and in the sea.

What group of animals rose to dominate the land after the end-Triassic extinction?

The end-Triassic extinction cleared out many rival reptiles, opening the way for dinosaurs to dominate.

What ended the reign of the non-avian dinosaurs 66 million years ago?

A huge asteroid struck near modern Mexico, filling the sky with dust and soot and collapsing food chains.

Grounded in trusted sources

Smithsonian National Museum of Natural History
United States Geological Survey (USGS)
National Geographic
Britannica

Every Wunder lesson is built from real, reputable sources — never invented.

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