Paleontologists agree that in Earth’s geological record, there’s evidence of five major extinction events, each marking the end of a geological period:
- The Ordovician mass extinction, 440- 445 million years ago, 86% of species disappeared.
- The Devonian mass extinction, 375-360 mya, 75% of species.
- The Permian mass extinction, 251 mya, 96% of species.
- The Triassic-Jurassic mass extinction, 199-214 mya, 75% of species.
- The Cretaceous mass extinction, 66 mya, 76% of species died, including dinosaurs.
But we may have to make room for another severe mass extinction event that has gone overlooked until now.
Is it the 6th or 7th Mass Extinction Event?
After each of these cataclysmic episodes, life almost completely vanished but found a way to bounce back, until the next mass die-off.
Scientists estimate that over 99% of all species that ever lived on the planet are extinct. It seems that whenever life recovered and flourished, the next mass extinction event was looming to bring it back to square one.
Now, researchers from New York University say they have discovered a new mass extinction event, which happened around 260 million years ago, in the Guadalupian, or the Middle Permian period.
The end-Guadalupian mass extinction likely killed 60% of all life on land and in the seas.
It’s not that scientists only now know of this mass die-off, but they previously underestimated its scale, considering it as a minor extinction event.
“In terms of both losses in the number of species and overall ecological damage, the end-Guadalupian event now ranks as a major mass extinction, similar to the other five,” the researchers write.
As to what caused the end-Guadalupian extinction event, it was likely a massive volcanic eruption. The extinction event seems to have occurred at the same time as the eruption that produced the rock formation known as the Emeishan Traps located in today’s China.
Massive volcanic eruptions can be much more deadly in the long term than immediately. When they erupt, massive volcanoes emit large amounts of carbon dioxide, methane, and other GHG gases, which lead to severe global warming, marked by warm and oxygen-poor oceans.
“It is crucial that we know the number of severe mass extinctions and their timing in order to investigate their causes,” says professor Michael Rampino, a co-author of the paper published in the journal Historical Biology.
Exactly! What’s the exact number of mass extinction events? Scientists think we’re already living in the midst of a major extinction event that’s slowly building-up momentum and could end up as severe as the other extinction events. So, if the end-Guadalupian is the sixth extinction event, that makes ours the seventh.
It seems that mass extinctions are more common than we thought. What else could we have missed, and what are going to do about the ongoing biodiversity loss?
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