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Posted on Apr. 16, 2019
The permissive secateurs of the Permian, a series of extinctions, including the Day of Judgment at the end of this period, known as "Great moribund who killed more than 95% of life on Earth", has cut the tree of life flourishing into a branch or two of the precursors of mammals, including that of our ancestors. It is the forgotten world of the Permian era, the supercontinent of Pangea, inhabited by our strange and fearsome cousins, long overshadowed by the epic reign of the dinosaurs that followed.
The idea that our parents ran the world more than 250 million years ago, continues Peter Brannen in The ends of the world"Could surprise those weaned on the idea that mammals did not make a difference until dinosaurs were destroyed by disaster, nearly 200 million years later. And that's true, because these Permian beasts – called synapsids – were still far from being true mammals. "
New researchers claim that mercury buried in ancient rocks is the strongest evidence ever seen of the fact that volcanoes have caused the largest mass extinction in the Earth's history. Palaeontologists at the University of Cincinnati and the Chinese University of Geosciences said they discovered a mercury spike in the geological archives of nearly a dozen sites worldwide, convincingly proving that volcanic eruptions are at the origin of the global cataclysm.
The eruptions ignited vast coal deposits, releasing mercury vapor into the atmosphere. Eventually, it rained in marine sediments around the planet, creating an elemental signature of a disaster that would herald the dinosaurs' age.
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"Volcanic activities, including volcanic gas emissions and the burning of organic matter, have released an abundant amount of mercury to the surface of the Earth," said senior author Jun Shen, associate professor at China. University of Geosciences.
Mass extinction has occurred to what scientists call the Permian-Triassic Frontier (PTB). Mass extinction has killed much of the land and marine life before the rise of the dinosaurs. Some were prehistoric monsters in their own right, such as the ferocious gorgonopsids that looked like a cross between a saber-toothed tiger and a Komodo dragon.
"The moments of the Permian twilight," writes Brannen, "belonged to the last great group of Permian mammal precursors: the therapsids. The theraspids included dicynodonts, dog-sized herbivores with giant tusks and beaks that probably trampled the shrubby countryside into herds. In an age earlier than flowers, fruits or grass, these phytophages had to fend for themselves in a world where nutrition was clearly inadequate. In fact, much of the planet was probably uninhabitable. The Ancestor Ocean of the Atlantic closed from the Ordovician, and thanks to the Permian, this marriage of the continents was consumed: the continental masses of the planet were united, after hundreds of millions of years, to form Pangea, a supercontinent giant who was expanding pole. The endless interior of this supercontinent was wildly dark and arid – a kind of global North Dakota – with a supernatural warmth and extreme cold, virtually insensitive to rain. "
The eruptions occurred in a volcanic system called the Siberian traps in present-day central Russia. Many eruptions did not occur in cone-shaped volcanoes, but in gaping soil cracks. The eruptions have been frequent and lasting and their fury has lasted hundreds of thousands of years.
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"Generally, when you have large and explosive volcanic eruptions, a large amount of mercury is released into the atmosphere," said Thomas Algeo, a professor of geology at the McMicken College of Art and Science. Columbia University.
"Mercury is a relatively new indicator for researchers. It has become a hot topic for studying volcanic influences on major events in Earth's history, "said Algeo.
Researchers use the fossilized sharp teeth of lamprey-like creatures, called conodonts, to date the rock in which the mercury was deposited. Like most other creatures on the planet, disasters have decimated conodonts.
The eruptions propelled not less than 3 million cubic kilometers of ash into the air during this extended period. To put this in perspective, the eruption of Mount St. Helens in 1980 in Washington sent only 1 cubic kilometer of ash into the atmosphere, even though the ashes fell on windshields car as far as Oklahoma.
In fact, he said, the Siberian eruptions created a quantity of matter in the air, especially greenhouse gases, which warmed the planet by an average of 10 degrees Celsius.
Global warming would probably have been one of the main culprits for this massive extinction, he said. But the acid rain would have spoiled many water plans and raised the acidity of the world's oceans. And the warmer water would have had more dead zones because of a lack of dissolved oxygen.
"We are often left wondering what was the most harmful. Creatures adapted to colder environments would not have been lucky, "said Algeo. "So, I guess the change in temperature would be the # 1 killer. The effects exacerbated by acidification and other toxins in the environment."
Extending over a prolonged period, eruption after eruption has prevented the Earth's food chain from recovering.
"It's not necessarily the intensity but the time that counts," said Algeo. "The longer it lasted, the more the environment was under pressure."
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Similarly, Earth has been slow to recover from the disaster as ongoing disturbances have continued to erode biodiversity, he said.
The Earth has witnessed five known mass extinctions over its 4.5 billion years.
Scientists have used another elemental signature – iridium – to pinpoint the probable cause of the global mass extinction that wiped out dinosaurs 65 million years ago. They believe that a huge meteor hit what is now Mexico.
The overheated plume of air thus blown into the atmosphere has resulted in a rain of iridium – containing material, which is found in geological records around the world.
Shen said the mercury signature provided compelling evidence that the eruptions of the Siberian traps were responsible for the disaster. Researchers are now trying to determine the extent of eruptions and what effects on the environment in particular have been most responsible for the mass mortality, especially for terrestrial animals and plants.
"The release of carbon into the atmosphere by humans is similar to the situation in the upper Permian, where carbon abundance was released by Siberian eruptions," said Shen.
Algeo said that it was a source of concern.
"A majority of biologists think we are on the threshold of another mass extinction – the sixth great. I share that view too, "said Algeo. "What we should learn is that it will be a serious matter that will hurt the human interest, so we must strive to minimize the damage.
People living in marginal environments such as arid deserts will suffer first. This will lead to more climate refugees around the world.
"We risk seeing more hunger and massive migration in the hardest hit areas. It is a global problem that we should recognize and deal with proactively. It is much easier to solve these problems before they are in crisis. "
The image at the top of the page shows a volcanic eruption that condemns a predatory gorgonopside during the Permian period. Margaret Weiner / UC Creative Services
The Daily Galaxy via the University of Cincinnati and Peter Brannen, The Ends of the World
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