iStock_56550000_LARGE

The first five mass extinctions

Are we heading for Earth’s sixth mass extinction? Let’s check out the tell-tale signs from the previous five.

Ordovician-Silurian

Advertisement

447 to 443 million years ago

The first mass extinction was caused by protocontinent Gondwana moving towards the South Pole, leading to global cooling, glaciation and a drop in sea level. Most life at the time was marine, and about 85 per cent of it vanished.

Late Devonian

375 to 360 million years ago

About 70 per cent of all species died in a series of extinction pulses. Marine life was particularly hard hit, with coral reefs disappearing almost entirely. The cause is unclear – possibly global cooling due to oceanic volcanism.

Permian-Triassic

252 million years ago

The worst extinction event, killing 90 to 96 per cent of species. The cause is debated but could have been a meteorite, volcanism or methane release that led to rapid climate change. Life took about 10 million years to recover.

Triassic-Jurassic

201.3 million years ago

Between 70 and 75 per cent of the Earth’s species went extinct at the end of the Triassic, including many large reptiles and amphibians. The cause is unknown, but the empty niches allowed dinosaurs to proliferate in the Jurassic.

Cretaceous-Paleogene

66 million years ago

This is probably the most famous mass extinction – it’s the asteroid impact that killed off the dinosaurs and about 75 per cent of species. Since then, birds and mammals have evolved to become the dominant land species.


Advertisement

Follow Science Focus on TwitterFacebook, Instagram and Flipboard