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Based on fossil records, around 252 million years ago over 90% of all species on Earth died out, effectively resetting evolution. (Image: Lunar and Planetary Institute)
Hey, remember that one time when 90% of all life on Earth got wiped out?
I don’t either. But it’s a good thing it happened because otherwise none of us would be here to… not remember it. Still, the end-Permian Extinction — a.k.a. the Great Dying — was very much a real crisis for life on Earth 252 million years ago. It makes the K-T extinction event of the dinosaurs look like a rather nice day by comparison, and is literally the most catastrophic event known to have ever befallen Earthly life. Luckily for us (and pretty much all of the species that have arisen since) the situation eventually sorted itself out. But how long did that take?
An alien Earth: what our planet looked like during the time of the Permian Extinction. (Via The Planetary Habitability Laboratory @ UPR Arecibo, NASA, Ron Blakey and Colorado Plateau Geosystems, Inc., and The PaleoMap Project)
The Permian Extinction was a perfect storm of geological events that resulted in the disappearance of over 90% of life on Earth — both on land and in the oceans. (Or ocean, as I should say, since at that time the land mass of Earth had gathered into one enormous continent — called Pangaea — and thus there was one ocean, referred to as Panthalassa.) A combination of increased volcanism, global warming, acid rain, ocean acidification and anoxia, and the loss of shallow sea habitats (due to the single large continent) set up a series of extinctions that nearly wiped our planet’s biological slate clean.
Exactly why the event occurred and how Earth returned to a state in which live could once again thrive is still debated by scientists, but it’s now been estimated that the recovery process took about 10 million years.
(Read: Recovering From a Mass Extinction is Slow Going)
Research by Dr. Zhong-Qiang Chen from the China University of Geosciences in Wuhan, and Professor Michael Benton from the University of Bristol, UK, show that repeated setbacks in conditions on Earth continued for 5 to 6 million years after the initial wave of extinctions. It appears that every time life would begin to recover within an ecological niche, another wave of environmental calamities would break.
“Life seemed to be getting back to normal when another crisis hit and set it back again,” said Prof. Benton. “The carbon crises were repeated many times, and then finally conditions became normal again after five million years or so.”
“The causes of the killing – global warming, acid rain, ocean acidification – sound eerily familiar to us today. Perhaps we can learn something from these ancient events.”
– Michael Benton, Professor of Vertebrate Palaeontology at the University of Bristol
It wasn’t until the severity of the crises abated that life could gradually begin reclaiming and rebuilding Earth’s ecosystems. New forms of life appeared, taking advantage of open niches to grab a foothold in a new world. It was then that many of the ecosystems we see today made their start, and opened the door for the rise of Earth’s most famous prehistoric critters: the dinosaurs.
“The event had re-set evolution,” said Benton. “However, the causes of the killing – global warming, acid rain, ocean acidification – sound eerily familiar to us today. Perhaps we can learn something from these ancient events.”
The team’s research was published in the May 27 issue of Nature Geoscience. Read more on the University of Bristol’s website here.
About Jason Major
A graphic designer living in Providence, RI, Jason writes about astronomy and space exploration on his blog Lights In The Dark, Discovery News and here on Universe Today.
