Mass extinction that triggered the dinosaur takeover of the world 233 million years ago is identified by scientists
- Volcanic eruptions in Canada spewed out vast amounts of greenhouse gases
- Led to a spike in rainfall and a million years of humidity followed by a dry period
- This change caused many species to go extinct and allowed dinosaurs to flourish
A previously unknown mass extinction has been discovered which occurred 233 million years ago.
Researchers spotted evidence of the so-called Carnial Pluvial Episode thanks to chemical signatures trapped in rock samples and fossils.
The mass extinction was triggered by volcanic eruptions in modern-day Canada which spewed out greenhouse gases, leading to rapid climate change.
It is the sixth mass extinction to be discovered and allowed dinosaurs, which were just emerging, to fill vacated environmental niches and take over the world.
This infographic offers a summary of major extinction events through time, highlighting the new, Carnian Pluvial Episode at 233 million years ago
A team of 17 researchers published a piece of research in Science Advances detailing how the eruptions from the Canadian Wrangellia Province unfolded.
The study was led by Jacopo Dal Corso of the China University of Geosciences at Wuhan and Mike Benton of the University of Bristol’s School of Earth Sciences.
Professor Dal Corso said: ‘So far, palaeontologists had identified five ‘big’ mass extinctions in the past 500 million years of the history of life.
‘Each of these had a profound effect on the evolution of the Earth and of life.
‘We have identified another great extinction event, and it evidently had a major role in helping to reset life on land and in the oceans, marking the origins of modern ecosystems.’
Signs of the Pluvial Episode were first detected in the 1980s when researchers identified a spike in rainfall.
It was also extremely humid and this combination caused major biodiversity loss in the ocean and on land.
Dinosaurs had been in existence for around 20 million years by this point but remained a relatively unimportant and small group of life on Earth.
However, after the humid period – which lasted about one million years and created coniferous forests – passed it led to a period of dry, arid conditions. This, Professor Benton says, was the window of opportunity dinosaurs needed to flourish
However, when the slate was wiped clean by the mass extinction new ecosystems formed which, researchers say, resembled modern day networks and were dominated by dinosaurs.
Professor Benton says the new vegetation that sprung up in the tropical climate would have been unsuitable for herbivorous reptiles, including dinosaurs, especially those at the top of the food chain.
But after the humid period – which lasted about one million years and created coniferous forests – passed it led to a period of arid conditions.
This, Professor Benton says, was the window of opportunity dinosaurs needed to flourish.
The dinosaurs dominated the landscape of both land, sea and air until their own mass extinction event 66 million years ago.
While dinosaurs capitalised on the window of opportunity after the mass extinction, so too did other animals, with the first mammals, turtles and crocodiles appearing.
EARTH HAS HAD FIVE GREAT EXTINCTION EVENTS WITH THE MOST FAMOUS A DINOSAUR KILLING ASTEROID
Five times, a vast majority of the world’s life has been snuffed out in what have been called mass extinctions.
End-Ordovician mass extinction
The first of the traditional big five extinction events, around 540 million years ago, was probably the second most severe. Virtually all life was in the sea at the time and around 85% of these species vanished.
Late Devonian mass extinction
About 375-359 million years ago, major environmental changes caused a drawn-out extinction event that wiped out major fish groups and stopped new coral reefs forming for 100 million years.
Five times, a vast majority of the world’s life has been snuffed out in what have been called mass extinctions. The most famous may be the End-Cretaceous, which wiped out the dinosaurs. Artist’s impression
End-Permian mass extinction (the Great Dying)
The largest extinction event and the one that affected the Earth’s ecology most profoundly took place 252 million years ago. As much as 97% of species that leave a fossil record disappeared forever.
End-Triassic mass extinction
Dinosaurs first appeared in the Early Triassic, but large amphibians and mammal-like reptiles were the dominant land animals. The rapid mass extinction that occurred 201 million years ago changed that.
End-Cretaceous mass extinction
An asteroid slammed down on Earth 66 million years ago, and is often blamed for ending the reign of the dinosaurs.
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