Earth’s five previous mass extinctions
End-Ordovician, 443 million years ago
A severe ice age led to sea level falling by 100m, wiping out 60-70% of all species which were prominently ocean dwellers at the time. Then soon after the ice melted leaving the oceans starved of oxygen.
Late Devonian, c 360 million years ago
A messy prolonged climate change event, again hitting life in shallow seas very hard, killing 70% of species including almost all corals.
Permian-Triassic, c 250 million years ago
The big one – more than 95% of species perished, including trilobites and giant insects – strongly linked to massive volcanic eruptions in Siberia that caused a savage episode of global warming.
Triassic-Jurassic, c 200 million years ago
Three-quarters of species were lost, again most likely due to another huge outburst of volcanism. It left the Earth clear for dinosaurs to flourish.
Cretaceous-Tertiary, 65 million years ago
An giant asteroid impact on Mexico, just after large volcanic eruptions in what is now India, saw the end of the dinosaurs and ammonites. Mammals, and eventually humans, took advantage.