The Great Dying: Earth's Worst Extinction
About 252 million years ago, roughly 90% of all species on Earth vanished. Not the dinosaurs — this happened long before dinosaurs even existed. Scientists call it the Permian-Triassic extinction, or simply 'the Great Dying,' and it remains the worst die-off life on Earth has ever survived.
What You'll Learn
- When the Great Dying happened and what era it ended - The leading scientific theory for what caused it - Which creatures disappeared and which strange survivors carried life forward - How fossils and rock layers tell scientists this story
What Caused It: The Siberian Traps
The main suspect is a massive series of volcanic eruptions in present-day Siberia, called the Siberian Traps. These eruptions didn't just spew lava — they released enormous amounts of carbon dioxide and methane over roughly one million years, possibly triggered by lava burning through coal and oil deposits underground. This likely caused rapid global warming, acid rain, and oceans that lost so much oxygen that sea creatures suffocated.
Who Vanished and Who Survived
Trilobites, hardy little sea creatures that had survived for almost 300 million years, disappeared completely. So did most ancient coral species. But a few tough survivors made it through, including Lystrosaurus, a stubby pig-sized creature with tusks that became the most common land animal on Earth right after the extinction — found on nearly every continent because there was so little competition left.
How We Know: Reading the Rock Layers
Paleontologists study a thin, dark rock layer found worldwide that marks this boundary between the Permian and Triassic periods. Below it, fossils show diverse thriving ecosystems. Just above it, fossils nearly disappear for a stretch of rock, then slowly reappear as new species evolve. That sudden change in fossil abundance is what tells scientists something catastrophic happened at that exact moment in Earth's history.
The asteroid that killed the dinosaurs 66 million years ago wiped out about 76% of species. The Great Dying wiped out roughly 90% — making it far deadlier, even though fewer people have heard of it.
What is the leading scientific explanation for the Great Dying?
Why was Lystrosaurus found on almost every continent right after the extinction?
Match each term to its meaning.
Terms
Definitions
Drag terms onto their definitions, or click a term then click a definition to match.
Build a Rock-Layer Timeline
Using a strip of paper divided into 3 sections (Before / During / After the extinction), draw or write which creatures existed in each section: trilobites and diverse corals in 'Before,' almost nothing in 'During,' and Lystrosaurus dominating in 'After.' Label the Permian-Triassic boundary between sections 1 and 2. Deliverable: your labeled 3-part timeline strip.
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