The Great Dying: The Permian-Triassic Extinction

[Mighty_Emperor]

Scientists Find Signs of Ancient Crater

Thu May 13, 5:07 PM ET

By RANDOLPH E. SCHMID, Associated Press Writer

WASHINGTON - Millions of years before the dinosaurs vanished, an even bigger mass extinction wiped out more than 90 percent of the species on Earth. Now scientists think they may have evidence of an impact crater that contributed to the "Great Dying."

The Permian-Triassic Extinction took place some 250 million years ago in a vastly different world from today. Scientists have debated its cause for years.

The end of the dinosaurs 65 million years ago is widely thought to have been caused by a meteor impact off Mexico's Yucatan Peninsula.

A team led by Luann Becker of the University of California, Santa Barbara, reported in Thursday's issue of the journal Science that a crater off the northwest coast of Australia shows evidence of a large meteor impact at the time of the early extinction.

They call it Bedout Crater (pronounced Beh-doo).

Vital to their conclusion was the discovery that core samples had been drilled in the region in the search for oil.

She said her team was "flabbergasted" when they looked at the never-before studied cores, which contained meteorite fragments, "shocked" quartz and other impact evidence.

In addition, quartz and other minerals blasted out by the impact have been found in Australia, Antarctica and possibly India, said Kevin Pope of Geo Eco Arc Research, a private geological research company in Aquasco, Md.

The impact occurred at the right time, so it is a good candidate for the cause of the extinction, said Robert Poreda of the University of Rochester, N.Y.

The prevailing theory about the cause of this extinction had blamed a series of volcanic eruptions over thousands of years that buried what is now Siberia in molten rock and released tons of toxic gases into the atmosphere, changing the Earth's climate.

The new find provides "suggestive ... but perhaps not yet compelling evidence" that an impact was involved, said Douglas H. Erwin, a senior paleobiologist at the Smithsonian's National Museum of Natural History.

This mass extinction was a fundamental transition in the history of life on Earth, Erwin said. He said further study will be done to try to confirm the new theory.

One difficulty, he said, is that there was a complex set of events occurring at the same time, including the eruptions in Siberia.

Perhaps more than one factor was involved, Becker said. "We think that mass extinctions may be defined by catastrophes like impact and volcanism occurring synchronously in time," Becker said.

Other scientists are skeptical.

"It's not yet persuasive that it's even a crater," said Peter D. Ward, a professor of geological sciences at the University of Washington in Seattle who has long studied impact craters and mass extinctions.

Intensive study is required to join the list of the world's proven impact craters. Most have been eroded by rain, wind and earthquakes over millions of years. This possible new site is poorly preserved and deeply buried.

Even if it is an impact crater, size must be proved, Ward said. "It's got to be a big hit" to cause global repercussions, he said. "There's going to have to be a tremendous amount of more work" done on the site.

Becker's team was funded by the National Aeronautics and Space Administration and the National Science Foundation

http://news.yahoo.com/news?tmpl=story&u=/ap/20040513/ap_on_sc/extinction_crater

 

[Mighty_Emperor]

A lack of evidence makes it a bit of a tricky theory

I believe the KT boundary can be found inside the Deccan Traps which suggests that it was business as usual there before and after the impact - a theory like that would need so testable hypothesis and I would imagine there would possibly be a change in eruptions or magma composition (other than the expected ones).

I do think it is possible that flood basalts may have started the extinctions a bolid impact may have finished it off. I don wonder if the climatic shifts it would have caused would have made it possible for a much smaller impact to cause the large scale climatic shifts that may have occured (i.e. while it is possible that a rare massive impact could have caused the extinctions when combined with a flood basalt event a smaller, more common, impact could have had a similar effect).

Another report:

May 14, 2004


Signs of Crater Linked to Mass Extinction Said Found


The world was not a great place to be 250 million years ago. That’s because some 90 percent of the planet’s marine life and 80 percent of life on land had gone extinct at the end of the Permian period. Exactly what caused the mass extinction is a matter of debate, with the two leading theories positing massive volcanism in Siberia or a collision with a meteor much like the one that killed the dinosaurs 65 million years ago. New findings published online today by the journal Science bolster the impact hypothesis and argue that the resulting crater lies buried off the coast of northwest Australia.

Luann Becker of the University of California at Santa Barbara and her colleagues studied two cores drilled by oil companies in the 1970s and 1980s into a geologic structure off the Australian coast known as the Bedout High. "The moment we saw the cores we thought it looked like an impact breccia," Becker says. Specifically, the team found what they say is evidence of a telltale melt layer that formed when a meteor crashed into the earth and created the 125-mile-wide Bedout. Additional support for their contention that Bedout is an impact crater comes from the fact that material from the cores dates to 250 million years ago, give or take 4.5 million years. Together with earlier evidence that Becker and her team collected in Antarctica and Australia--including shocked quartz and molecules called fullerenes containing extraterrestrial helium and argon--the new results provide further evidence that a massive impact brought about the Great Dying, the scientists say. "We think that mass extinctions may be defined by catastrophes like impact and volcanism occurring synchronously in time," Becker remarks. "This is what happened 65 million years ago at Chicxulub but was largely dismissed by scientists as merely a coincidence. With the discovery of Bedout I don't think we can call such catastrophes occurring together a coincidence anymore."

The findings do not close the case of exactly what caused the Permian-Triassic (P-T) extinction, however. Some scientists remain unconvinced that Bedout is in fact an impact crater. In addition, although the date given in the new paper is consistent with the timing of the P-T dieout, it is not yet exact enough to be considered simultaneous with the extinction. Becker notes that the team plans to pursue more precise dating. “Evidence for an impact [at the end of the Permian era] has been growing over the last few years,” notes Doug Erwin of the Smithsonian Institution in Washington, D.C. “It’s not yet a slam dunk, but [the new work] makes it a more plausible contender.”

http://www.sciam.com/article.cfm?chanID=sa003&articleID=0002C42F-DB79-10A3-9B7983414B7F0000

Emps

 

[Mighty_Emperor]

1 December 2004

Geologists Say End-Permian Mass Extinction Not Caused By Asteroid

The world's largest mass extinction occurred some 250 million years ago, wiping out 90 percent of marine life. While some scientists have speculated that an asteroid impact might be to blame, the cause of this great dying has remained a mystery. But a new study published in Geology provides evidence that the cause of the extinction did not come from the heavens, but from the Earth itself.

A team of scientists led by Christian Koeberl from the University of Vienna have been studying rock samples taken from mountain ranges in Western Europe. The layers of rocks contain a record of environmental change though time. Asteroids and comets are chemically different from the Earth and when these objects arrive they leave a tell-tale chemical fingerprint in the rocks. Koeberl confirmed the presence of the element iridium in the samples. Iridium is abundant in asteroids, comets, and other extraterrestrial material. However, the amounts found were very small compared to those associated with the asteroid impact that many scientists believe killed off the dinosaurs 65 million years ago. At the same time, the team found no traces of the extraterrestrial isotopes helium-3 and osmium-187, commonly associated with impact events.

"Our geochemical analyses of these two famous end-Permian sections in Austria and Italy reveal no tangible evidence of extraterrestrial impact," said Koeberl. "This suggests the mass extinction must have been home-grown."

What the team found was evidence of purely terrestrial processes at work. According to Koeberl, "The slight concentrations of iridium may have been deposited by sluggish oceans when atmospheric carbon dioxide levels were high and seawater oxygen levels were low. The source of the carbon dioxide was probably volcanic activity."

The researchers say that massive volcanic activity in the heart of present day Siberia led to changes in climate and patterns of oceanic circulation. "Our findings support the view that evidence for an extraterrestrial impact event during this time period is weak and inconsistent," said Koeberl. "At the same time, they suggest that widespread volcanic activity may have been the 'smoking gun,' quite literally, that wiped out much of life on Earth."

Source

 

[KeyserXSoze]

http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2004/12/13/MNGPRAB3QC1.DTL

Scientists clash over origin of 'the Great Dying'
Volcanic, celestial theories on extinction 250 million years ago take stage in S.F.
- David Perlman, Chronicle Science Editor
Monday, December 13, 2004

A cataclysm 250 million years ago wiped out nearly all life in the Earth's oceans, and nearly three-quarters of the plants and animals on land vanished too. It was the greatest catastrophe the Earth has ever experienced - - but scientists who study such events are in sharp disagreement over what caused it.

Was it the crash of a giant asteroid or meteorite that killed off so much life? Or was a violent surge of volcanism from deep within the Earth the deadly factor?

The argument over sketchy evidence from the long-ago geologic time called the "End Permian" persists, and the contentious scientific debate will continue this week when the American Geophysical Union meets at Moscone Center, with nearly 11,000 scientists in attendance.

Scientists do agree that the mass extinction was sudden: The Earth is known to be at least 4 billion years old, and "the Great Dying," as paleontologists call it, may have lasted less than 200,000 years from start to finish, a mere moment in geologic time.

In the most recent stage of the controversy, teams of researchers have squared off in support of two opposing theories to explain what triggered the disaster.

One international research group, led by Christian Koeberl of the University of Vienna and Kenneth Farley of the California Institute of Technology, is arguing that there is no hard evidence at all to support the impact theory.

Newly discovered chemical signs in the Austrian Alps and the Italian Dolomites, where elements typical of asteroids or meteorites are almost nonexistent, is one key to their argument.

Koeberl and Farley, as well as many other geochemists, say the extinction was more likely due to an immense outpouring of lava in the northern part of a once huge super-continent known as Pangaea. The remains of that event can be found today in a vast surface region of basaltic rock in northern Russia known as the Siberian Traps.

The volcanic violence would have induced abrupt global heating, throwing up a dark pall of hot ash, toxic gases and carbon dioxide that virtually no living plants or animals could survive, according to this theory. The darkness of the skies then would have caused a major period of global cold.

Farley, Koeberl and their colleagues have just published their arguments in the December issue of the journal Geology.

"Our findings support the view that evidence for an extraterrestrial impact event is weak and inconsistent," Koeberl commented by e-mail. "At the same time, they suggest that widespread volcanic activity may have been the 'smoking gun,' quite literally, that wiped out much of life on Earth."

But another team, including Luann Becker of UC Santa Barbara and Asish Basu of the University of Rochester in New York, insists that ancient meteorite fragments discovered in Antarctica -- and traces of the unique isotope of helium in Antarctic rocks -- clearly show that when Pangaea was forming, a gigantic meteorite must have crashed into the Southern Hemisphere.

That impact created an enormous crater hundreds of miles wide that may be located now in the seabed beneath the Indian Ocean off Australia's northwestern coast, on the edge of a seismically active desert region called the Canning Basin. Becker believes that a submerged mountain there called the Bedout High (pronounced Be-doo) could be the central peak of the long-vanished crater.

The crater-forming blast could have darkened the skies, raised a life- choking cloud of dust, rock fragments and gases, and created what the late Carl Sagan and his colleagues 20 years ago termed a "nuclear winter," Basu and Becker argue.

They and their colleagues published their view of the mass extinction's causes in the journal Science last year, and pinpointed the Bedout High as the best evidence for impact in another Science report last May.

The time when all life succumbed is known as the boundary between the end of the Permian period -- an epoch that lasted from 286 to 245 million years ago -- and the start of the Triassic period, when life flourished anew and the dinosaurs evolved, ultimately to rule the Earth.

The dinosaurs disappeared during the second greatest mass extinction known in Earth's history. This event took place some 65 million years ago when -- as almost all paleontologists and geologists agree -- an asteroid impact extinguished 70 percent of Earth's life and created a wide crater called Chixchilub that now lies under the sea just off the Yucatan Peninsula.

One of the main pieces of evidence supporting an extraterrestrial impact for the dinosaur-killing event is a thin layer of the element iridium in rock formations around the world, discovered almost 25 years ago by Walter Alvarez of UC Berkeley. Iridium is rare on Earth but common in asteroids. Other evidence is the widespread presence of tiny grains of shocked quartz -- quartz that was subjected to some violent impact -- and the presence of an isotope of helium -- unique in nature to extraterrestrial objects like meteorites, asteroids and the moon -- in the layers of iridium and other rocks.

According to Basu and Becker, iridium was rare in the rock samples Becker found in Antarctica -- but there was plenty of shocked quartz and many fragments of what could only be extremely ancient meteorites, they reported. And in many formations from the end of the Permian period, they said, they found clear signs of the crucial evidence: the presence of the unique extraterrestrial isotope of helium, known as helium-3.

Farley, however, is an expert on the so-called noble gases, including helium, and in all his laboratory tests he insists he has been unable to find any trace of the extraterrestrial gases in the very same formations that Becker and Basu have studied.

"There's absolutely no evidence of an extraterrestrial impact in any of the formations that date from the end of the Permian period," Farley said.

To which Basu responded by telephone: "As the late Carl Sagan always said, 'The absence of evidence is not evidence of absence.' " In other words, just because Farley can't find helium-3 does not prove it isn't there.

As a kind of neutral observer, Paul R. Renne, who directs the Berkeley Geochronology Center, weighed in the other day. Renne's center is where he and his fellow scientists determine the ages of the ancient rocks and fossils that scientists find all over the world, and they have examined the evidence on both sides.

"The debate is a real mess scientifically," Renne told The Chronicle, "but there's massive doubt about the work in Antarctica, and there's no really consistent evidence to support it."

The argument over what in fact wiped out so much of life on Earth some 250 million years ago is bound to continue for a long, long time, and only a month ago in letters to the Science, no fewer than eight scientists who study the issue called the report by Becker and Basu a sensationalistic claim.

To which Becker replied, in an angry statement to the journal Nature, "this is science by intimidation."

 

[ramonmercado]

Meteor Impact Theory Takes a Hit

Meteor Impact Theory Takes a Hit
By Amit Asaravala
Story location: http://www.wired.com/news/technology/0, ... 45,00.html

11:40 AM Jan. 20, 2005 PT

The catastrophe that killed off the majority of life on Earth 250 million years ago was not a meteorite impact, but a gradual rise in global temperatures, according to a new study published Thursday on the website of the journal Science.

The study is the second in two months to question the validity of the meteorite impact theory, which suggests that a giant asteroid or comet struck the Earth with such force that it led to a massive, global extinction that scientists call the "Great Dying."

The impact would have been similar to the one that is widely believed to have led to the extinction of the dinosaurs 65 million years ago. But to date, evidence for the dinosaur's demise has far exceeded that for the Great Dying.

"We all assumed in the scientific community that if one extinction could be caused by an impact, they all could," said Peter Ward, a University of Washington paleontologist and lead author of the new study. "I went (to South Africa) specifically to prove that this was caused by an impact and walked out of there thinking that, no, it wasn't."

Ward and his fellow researchers traveled to the Karoo Basin in South Africa to examine fossils that have been traced back to the time of the Great Dying, also known as the end-Permian period. Rather than finding that a great number of animals and plants had all died at once, however, the team detected signs of a gradual extinction over nearly 10 million years. Then, a second extinction seems to have started and lasted approximately 5 million years.

Such patterns suggest that long-term environmental changes, like global warming and falling oxygen levels, are more to blame than a meteor impact, said Ward. Continuous volcanic eruptions during the end-Permian period could have contributed to these changes by triggering the release of methane that had previously been frozen at the bottom of the ocean, he suggested.

Ward added that the team did not find, in the sediment that it examined, the sorts of minerals that are normally associated with meteorite impacts. Those minerals include iridium, which hitches a ride to Earth on asteroids, and "shocked" quartz, which takes on an altered appearance after a massive impact.

The findings -- or lack thereof -- contradict a controversial study published in June 2004 by Science. In that study, University of California at Santa Barbara geologist Luann Becker and several other scientists claimed to have discovered evidence of a giant impact crater off the coast of Australia. The crater could be dated back to the beginning of the Great Dying, they wrote in the study, making it the likely cause of the mass extinction.

However, a number of geologists have since questioned the evidence.

"They've been very broadly criticized," said Paul Renne, director of the Berkeley Geochronology Center. "Many of their claims are completely unsupportable."

The impact theory received another major blow in December when a team led by geologist Christian Koeberl from the University of Vienna published a paper in the journal Geology showing that samples of end-Permian rock in Western Europe did not contain iridium and shocked quartz.

University of Rochester geochemist Robert Poreda, who co-authored the June impact paper with Becker, defended his team's study Wednesday and said that he still supported the impact theory.

"A lot of things can explain why there was no evidence of shocked quartz," he said. "For one, there's not a complete section (of sediment) to analyze at Karoo."

In addition, an impact off the coast of Australia would not have struck the appropriate rocks that would lead to the creation of mass quantities of shocked quartz, he said. Plus, an impact by a comet -- not an asteroid -- would probably not have carried iridium with it, he added.

Berkeley's Renne, who was not involved in any of the aforementioned studies, agreed that Poreda's arguments are valid. However, he noted that he and many of his colleagues were beginning to have less and less faith in the impact theory. Indeed, Renne's own research supports the idea that the extinction occurred gradually, he said.

"We've found that the atmosphere was changing, in terms of oxygen levels and in carbon and so on -- all told, these things were probably going on over a million years," he said. "And we're beginning to think that the main pulse of extinction occurred over 100,000 years, which is pretty fast in geologic time, but it's not an instant."

To resolve the argument, scientists are now turning their attention to fullerenes, tiny balls of carbon that can lock up gases inside. If fullerenes taken from sediment dated back to the beginning of the Great Dying are found to contain gases more commonly found in space than on Earth, the chances are good that a large meteorite struck the planet around the same time.

But even this technique has its problems, warned Renne.

"A lot of things have to be done to establish a link between the gases in the fullerenes and an impact," he said. "The timing (of any detected impact) has to be perfect, and it has to be shown that this is an anomalous concentration of gas."

 

[painy2]

Meteor Impact Theory Takes a Hit

11:40 AM Jan. 20, 2005 PT

The catastrophe that killed off the majority of life on Earth 250 million years ago was not a meteorite impact, but a gradual rise in global temperatures, according to a new study published Thursday on the website of the journal Science.

The study is the second in two months to question the validity of the meteorite impact theory, which suggests that a giant asteroid or comet struck the Earth with such force that it led to a massive, global extinction that scientists call the "Great Dying."

The impact would have been similar to the one that is widely believed to have led to the extinction of the dinosaurs 65 million years ago. But to date, evidence for the dinosaur's demise has far exceeded that for the Great Dying.

"We all assumed in the scientific community that if one extinction could be caused by an impact, they all could," said Peter Ward, a University of Washington paleontologist and lead author of the new study. "I went (to South Africa) specifically to prove that this was caused by an impact and walked out of there thinking that, no, it wasn't."

Ward and his fellow researchers traveled to the Karoo Basin in South Africa to examine fossils that have been traced back to the time of the Great Dying, also known as the end-Permian period. Rather than finding that a great number of animals and plants had all died at once, however, the team detected signs of a gradual extinction over nearly 10 million years. Then, a second extinction seems to have started and lasted approximately 5 million years.

Such patterns suggest that long-term environmental changes, like global warming and falling oxygen levels, are more to blame than a meteor impact, said Ward. Continuous volcanic eruptions during the end-Permian period could have contributed to these changes by triggering the release of methane that had previously been frozen at the bottom of the ocean, he suggested.

Ward added that the team did not find, in the sediment that it examined, the sorts of minerals that are normally associated with meteorite impacts. Those minerals include iridium, which hitches a ride to Earth on asteroids, and "shocked" quartz, which takes on an altered appearance after a massive impact.

The findings -- or lack thereof -- contradict a controversial study published in June 2004 by Science. In that study, University of California at Santa Barbara geologist Luann Becker and several other scientists claimed to have discovered evidence of a giant impact crater off the coast of Australia. The crater could be dated back to the beginning of the Great Dying, they wrote in the study, making it the likely cause of the mass extinction.

Link is here for the rest of the story

wired.com/news/technology/0,1282,66345,00.html?tw=wn_2techhead
Link is dead. The MIA webpage can be accessed via the Wayback Machine:
https://web.archive.org/web/2005040...chnology/0,1282,66345,00.html?tw=wn_2techhead

 

[sunsplash1]

Another big meteoroid collision in ages past

Giant meteor spawned Australian continent, scientists say

A meteor which crashed into Antarctica probably caused the biggest mass extinction in the Earth's history and likely spawned the Australian continent, scientists say.

Ohio State University scientists say the 483 kilometre wide crater is now hidden more than 1.6 kilometres beneath the East Antarctic Ice Sheet.

"Gravity measurements that reveal its existence suggest that it could date back about 250 million years, the time of the Permian-Triassic extinction, when almost all animal life on Earth died out," the university said in a statement.

"Its size and location, in the Wilkes Land region of East Antarctica, south of Australia, also suggest that it could have begun the break-up of the Gondwana supercontinent by creating the tectonic rift that pushed Australia northward," they added.

Scientists believe that the Permian-Triassic extinction paved the way for the dinosaurs to rise to prominence.

The Wilkes Land crater is more than twice the size of the Chicxulub crater in Mexico's Yucatan peninsula, which marks the impact that may have ultimately killed the dinosaurs 65 million years ago.

The Chicxulub meteor is thought to have been 9.6 kilometres wide, while the Wilkes Land meteor could have been up to 48.3 kilometres wide, four or five times wider.

"This Wilkes Land impact is much bigger than the impact that killed the dinosaurs, and probably would have caused catastrophic damage at the time," Ralph von Frese, a professor of geological sciences at Ohio State, said.

He and Laramie Potts, a postdoctoral researcher in geological sciences, led the team that discovered the crater.

They collaborated with other Ohio State and NASA scientists, as well as partners from Russia and South Korea.

They have reported their preliminary results in a recent American Geophysical Union Joint Assembly meeting in Baltimore, Maryland.

Some 100 million years ago, Australia split from the ancient Gondwana supercontinent and began drifting north, pushed away by expansion of a rift valley into the eastern Indian Ocean.

The rift cuts directly through the crater, so the impact may have helped the rift to form, Professor von Frese says.

The more immediate effects of the impact, however, would have devastated life on Earth.

"All the environmental changes that would have resulted from the impact would have created a highly caustic environment that was really hard to endure. So it makes sense that a lot of life went extinct at that time," he said.

http://www.abc.net.au/news/newsitems/200606/s1654415.htm

Another Permian~Triassic event?

 

[pintquaff]

i dont know if this can be answered in laymens terms but how do they date the age of a meteroid impact? espcially when it is 1.6k below the surface.

 

[feen5]

I presume they use the surrounding geology to date the age of the meteor crater. Rocks can be dated quite accuaralty and their has been plenty of drilling (scientific and explorational) carried out in Antartic. As well as that geophysical, magnetic and seismic surveys can not only give you a map of the underlying rock structure but also the composition of the rocks. All of this information and probably a hell of a lot more that i wouldn't know about could accuratly date the rocks.

 

[sunsplash1]

Yep. Core sample. unbelievable what you can tell from a core sample...

 

[BookOfMysteries]

I presume they use the surrounding geology to date the age of the meteor crater. Rocks can be dated quite accuaralty and their has been plenty of drilling (scientific and explorational) carried out in Antartic. As well as that geophysical, magnetic and seismic surveys can not only give you a map of the underlying rock structure but also the composition of the rocks. All of this information and probably a hell of a lot more that i wouldn't know about could accuratly date the rocks.

So what is the first dated object from which the other relative dates come?

I ask since I thought this was a Fortean forum not a debunker forum and I remember how amused Charles Fort was in his books at scientific churchmen and their inevitable pronouncements...

It would be so refreshing to have Fort around to weigh into this one with impossible fossils, common sense and harsh logic.

 

[ramonmercado]

Did an eco-disaster spawn complex life?
19:00 23 November 2006
NewScientist.com news service
Jeff Hecht


The upper portion of the image represents marine life in the time before the mass extinction; the lower portion represents marine life after the mass extinction (Graphic: Ron Testa, manipulated by Scott Lidgard) The greatest mass extinction of all time led to the proliferation of complex marine life that quickly dominated the undersea scene, according to a new analysis of the fossil record.

Palaeontologists have long assumed that ecosystems grew steadily more complex since the first hard-shelled animals evolved about 540 million years ago. But Peter Wagner of the Field Museum in Chicago, US, found something different when he examined data on 1176 marine ecosystems stored in the massive Paleobiology Database.

The Permian extinction occurred 251 million years ago and wiped out 95% of marine species. Before this “great dying”, simple and complex marine ecosystems were equally abundant. But afterwards, complex ecosystems became three times as common - a ratio that has persisted ever since, Wagner says.

Stationary filter-feeders
Simple marine ecosystems consist of a few very abundant but stationary animals, such as crinoids and brachiopods (lamp-shells), which filter food from the water and leave few resources for less common species, whose population sizes remain low as a result.

Complex ecosystems divide resources among many more active organisms, such as clams and snails, and include many more species that interact in complex ways.

"We don't really have a mechanism [to explain the shift],” Wagner told New Scientist. Other mass extinctions did not change the ratio. But the end-Permian may have devastated the marine ecosystem so severely "that basically something new grew in its place", he speculates.

Our modern marine world may never have come into existence if it were not for the Permian extinction, he adds.

Journal reference: Science, vol 314, p 1254

Related Articles

Climate blamed for mass extinctions
http://www.newscientist.com/article.ns? ... 025453.700
03 April 2006

Mountain clue to Earth's biggest extinction
http://www.newscientist.com/article.ns? ... 825295.600
13 December 2005

Wipeout
http://www.newscientist.com/article.ns? ... 922801.700
03 March 2001

Weblinks

Paleobiology Database
http://paleodb.org

Field Museum, Chicago
http://www.fieldmuseum.org/

Peter Wagner
http://fm1.fieldmuseum.org/aa/staff_pag ... f=p_wagner

Science
http://www.sciencemag.org/

www.newscientist.com/article/dn10652-di ... -life.html

 

[ramonmercado]

A Sea Of Complexity

Illustration of a Plesiosaurs dinosaur. Copyright: Doug Henderson.
by Staff Writers
Chicago Il (SPX) Nov 27, 2006

The earth experienced its biggest mass extinction about 250 million years ago, an event that wiped out an estimated 95% of marine species and 70% of land species. New research shows that this mass extinction did more than eliminate species: it fundamentally changed the basic ecology of the world's oceans.
Ecologically simple marine communities were largely displaced by complex communities. Furthermore, this apparently abrupt shift set a new pattern that has continued ever since. It reflects the current dominance of higher-metabolism, mobile organisms (such as snails, clams and crabs) that actually go out and find their own food and the decreased diversity of older groups of low-metabolism, stationary organisms (such as lamp shells and sea lilies) that filter nutrients from the water.

So says research published in Science on November 24, 2006. An accompanying article suggests that this striking change escaped detection until now because previous research relied on single numbers--such as the number of species alive at one particular time or the distribution of species in a local community--to track the diversity of marine life. In the new research, however, scientists examined the relative abundance of marine life forms in communities over the past 540 million years.

One reason they were able to do this is because they tapped the new Paleobiology Database, a huge repository of fossil occurrence data. The result is the first broad objective measurement of changes in the complexity of marine ecology over the Phanerozoic.

"We were able to combine a huge data set with new quantitative analyses," says Peter J. Wagner, Associate Curator of Fossil Invertebrates at The Field Museum and lead author of the study. "We think these are the first analyses of this type at this large scale. They show that the end-Permian mass extinction permanently altered not just taxonomic diversity but also the prevailing marine ecosystem structure."

Specifically, the data and analyses concern models of relative abundance found in fossil communities throughout the Phanerozoic. The ecological implications are striking. Simple marine ecosystems suggest that bottom-dwelling organisms partitioned their resources similarly. Complex marine ecosystems suggest that interactions among different species, as well as a greater variety of ways of life, affected abundance distributions. Prior to the end-Permian mass extinction, both types of marine ecosystems (complex and simple) were equally common. After the mass extinction, however, the complex communities outnumbered the simple communities nearly 3:1.

The other authors are Scott Lidgard, Associate Curator of Fossil Invertebrates at The Field Museum, and Matthew A. Kosnik, from the School of Marine and Tropical Biology at the James Cook University in Townsville, Queensland, Australia.

"Tracing how marine communities became more complex over hundreds of millions of years is important because it shows us that there was not an inexorable trend towards modern ecosystems," Wagner said. "If not for this one enormous extinction event at the end of the Permian, then marine ecosystems today might still be like they were 250 million years ago."

These results also might provide a wake-up call, Wagner added: "Studies by modern marine ecologists suggest that humans are reducing certain marine ecosystems to something reminiscent of 550 million years ago, prior to the explosion of animal diversity. The asteroid that wiped out the dinosaurs couldn't manage that."

Lidgard added, "When Pete walked into my office with his preliminary results, I simply couldn't believe them. Paleontologists had long recognized that ecosystems had become more complex, from the origin of single-celled bacteria to the present day. But we had little idea of just how profoundly this one mass extinction--but not the others like it--changed the marine world."

http://www.terradaily.com/reports/A_Sea ... y_999.html

 

[bazizmaduno]

Did an eco-disaster spawn complex life?

No. I don't think so.

I would say, however, that it seems likely that complex life has spawned an eco-disaster. 8)

 

[ramonmercado]

Did an eco-disaster spawn complex life?

No. I don't think so.

I would say, however, that it seems likely that complex life has spawned an eco-disaster. 8)

Excellent!

 

[EnolaGaia]

Canada’s Arctic islands yield new clues in ancient mass extinction

BY RANDY BOSWELL, POSTMEDIA NEWS JULY 14, 2013

Canadian scientists probing two sites in the High Arctic have found fresh evidence pointing to a fiery Siberian suspect in the greatest mass extinction of all time — a planet-wide cataclysm that wiped out more than 90 per cent of the Earth’s species about 250 million years ago.

The so-called “Great Dying” at the end of the Permian geological era killed off a larger proportion of species than any of the 25 other mass extinctions scientists have identified from sudden and widespread gaps in the fossil record at certain layers of rock corresponding to specific periods of time.

The precise cause of the biological catastrophe 252 million years ago has been debated by scientists for decades. But nothing else in Earth history compares to the Late Permian disaster, which eclipsed 95 per cent of all marine life and about 70 per cent of species on land.

Some have argued that a massive meteorite strike — like the one widely presumed to have triggered the end of the dinosaur age 65 million years ago — must have been to blame. Others point to extreme climate change linked to ocean acidification, oxygen depletion, mercury poisoning or other species-snuffing effects as the main driver of the extinctions.

And without discounting the other forces as potential contributors to the Great Dying, a growing number of scientists — including several groups of Canadian researchers who are among the world’s leading investigators of the die-off — have fingered a prolonged series of enormous volcanic eruptions in northern Asia known as the “Siberian Traps” as the main culprit in the Permian extinction.

The latest clues in the prehistoric puzzle, which reinforce the volcanism theory, come from Ellesmere Island and nearby Axel Heiberg Island in the Canadian Arctic, where five researchers from the University of Calgary and the Geological Survey of Canada have found evidence undercutting the idea that oxygen depletion occurred uniformly throughout the world’s oceans and may have been the prime agent of death in the Great Dying.

At Axel Heiberg’s Lake Buchanan and Ellesmere’s West Blind Fiord, geological sites offering two of the best-known windows on the Permian extinction, the Canadian team tested rock samples for the element molybdenum — a “powerful tracer” used in reconstructing the oxygen levels of ancient marine environments — to better understand what was happening in waters off the coast of the supercontinent Pangea 252 million years ago.

At that time, the now-exposed Lake Buchanan and West Blind Fiord sites were lying at the bottom of the primordial ocean close to the equator.

The researchers, led by U of C geoscientist Bernadette Proemse, determined that the Lake Buchanan site — which preserves a deep-water seabed environment from the time of the Great Dying — showed clear signs of “anoxia” or extreme oxygen deprivation.

But the shallower Permian seafloor found at West Blind Fiord, which preserves a stretch of Pangea’s extinction-era continental shelf, showed a fairly well-oxygenated marine environment even as the Great Dying was unfolding.

In short, the findings confirm oxygen starvation as a significant factor in some phases or sites of the global crisis, but rule it out as the underlying cause of the planet-spanning extinctions, the researchers conclude.

Their study was published in the latest issue of the journal Geology.

“It is clear that anoxia cannot be the direct cause of the extinction,” the scientists argue, pointing to the oxygenated seawater available at the Ellesmere Island site. “Rather than the direct cause of global extinction, anoxia may be more a contributing factor along with numerous other impacts associated with Siberian Traps eruption and other perturbations to the Earth system.”

The impacts from the Siberian eruptions, “the largest volcanic event in Earth history, are increasingly recognized as devastating to global ecosystems” at the end of the Permian era, the researchers added. “Widespread anoxic conditions are more likely a symptom of other external factors placing multiple stresses on the global environment due to massive eruptions of the Siberian Traps at that time.”

Traces of the ancient volcanic calamity itself can be seen across a wide area of present-day Russia near the Siberian city of Norilsk.

The researchers involved in the new Geology study have published previous papers on the Permian extinction. Co-authors Stephen Grasby, a GSC geologist who also teaches at the University of Calgary, and fellow U of C scientist Benoit Beauchamp collaborated on a 2011 research project that pointed to layers of coal ash found at Lake Buchanan as “smoking gun” proof that the fiery Siberian Traps were wreaking havoc on the global climate and suffocating life almost everywhere around the world.

In 2008, another team of Canadian scientists announced the discovery of a thin band of rock running through B.C., Alberta and Arctic Canada that appears to have served as a rare coastal refuge for life during the Great Dying.

The refuge was identified by its diverse and abundant deposits of fossils, proof that a “thriving” array of clams, worms and other seabed species endured in at least one narrow strip of ancient Canada at time when nearly all of the world’s other terrestrial and marine ecosystems had become poisonous to life.

SOURCE: http://www.canada.com/technology/Canada ... story.html

 

[EnolaGaia]

Here's an interesting analysis of the oceanic effects that doomed most of the marine life.

How Rising Temperatures Suffocated 96 Percent of Sea Life in Earth's Biggest Extinction
Scientists believe a series of violent volcanic eruptions occurred in what is today Siberia, pumping greenhouse gases like carbon dioxide and methane into the atmosphere, which warmed the planet.

Then came the "Great Dying." About 96 percent of creatures in the ocean and 70 percent of terrestrial species living on the supercontinent Pangaea went extinct in a matter of several thousand years ... The so-called Permian-Triassic mass extinction event was the worst in Earth's history. ...

Researchers have long sought to understand how this die-off played out. In a study published in the Dec. 7 issue of the journal Science, a group of scientists offered an account for how this mass extinction event killed so many ocean creatures. The study showed how warming waters couldn't hold enough oxygen to support most life. ...

"This is the first time that we have made a mechanistic prediction about what caused the extinction that can be directly tested with the fossil record, which then allows us to make predictions about the causes of extinction in the future," the first author of the study, Justin Penn, said ...

Penn and his colleagues ran a computer simulation of the changing conditions Earth experienced during the transition from the Permian to the Triassic, with ocean surface temperatures in the tropics rising by 20 degrees Fahrenheit (11 degrees Celsius).

In the researchers' model, ocean circulation became quite stagnant and about 76 percent of marine oxygen was depleted around the globe. Oxygen loss varied according to geography, generally hitting deeper waters hardest; about 40 percent of seafloor environments totally lacked oxygen after this transition. ...

FULL STORY: https://www.livescience.com/64270-animals-suffocated-permian-extinction.html

Details for the Publication in Science:

Temperature-dependent hypoxia explains biogeography and severity of end-Permian marine mass extinction
Justin L. Penn, Curtis Deutsch, Jonathan L. Payne, Erik A. Sperling
Science 07 Dec 2018:
Vol. 362, Issue 6419, eaat1327
DOI: 10.1126/science.aat1327

 

[Jim]

An interesting discussion on the end of the Permian period, which ended the Paleozoic era (early era). The Permian - Triassic transition is thought to be the earth's most catastrophic extinction event to date.
https://www.nationalgeographic.com/science/prehistoric-world/permian-extinction/

 

[EnolaGaia]

The Great Dying seems to have been a more complex event than previously believed. New dating results have confirmed the progressive extinctions on land appear to have been underway hundreds of thousands of years before the even more comprehensive extinctions in the seas.

In Earth's largest extinction, land animal die-offs began long before marine extinction

The mass extinction at the end of the Permian Peri od 252 million years ago -- one of the great turnovers of life on Earth -- appears to have played out differently and at different times on land and in the sea, according to newly redated fossils beds from South Africa and Australia.

New ages for fossilized vertebrates that lived just after the demise of the fauna that dominated the late Permian show that the ecosystem changes began hundreds of thousands of years earlier on land than in the sea, eventually resulting in the demise of up to 70% of terrestrial vertebrate species. The later marine extinction, in which nearly 95% of ocean species disappeared, may have occurred over the time span of tens of thousands of years.

Though most scientists believe that a series of volcanic eruptions, occurring in large pulses over a period of a million years in what is now Siberia, were the primary cause of the end-Permian extinction, the lag between the land extinction in the Southern Hemisphere and the marine extinction in the Northern Hemisphere suggests different immediate causes.

"Most people thought that the terrestrial collapse started at the same time as the marine collapse, and that it happened at the same time in the Southern Hemisphere and in the Northern Hemisphere," said paleobotanist Cindy Looy, University of California, Berkeley, associate professor of integrative biology. "The fact that the big changes were not synchronous in the Northern and Southern hemispheres has a big effect on hypotheses for what caused the extinction. An extinction in the ocean does not, per se, have to have the same cause or mechanism as an extinction that happened on land."

Members of Looy's lab have conducted experiments on living plants to determine whether a collapse of Earth's protective ozone layer may have irradiated and wiped out plant species. Other global changes -- a warming climate, a rise in carbon dioxide in the atmosphere and an increase in ocean acidification -- also occurred around the end of the Permian period and the beginning of the Triassic and likely contributed. ...

"For some years now, we have known that -- in contrast to the marine mass extinction -- the pulses of disturbance of life on land continued deep into the Triassic Period. But that the start of the terrestrial turnover happened so long before the marine extinction was a surprise." ...

FULL STORY: https://www.eurekalert.org/pub_releases/2020-03/uoc--iel032720.php

 

[Lord Lucan]

I own a very small piece of this. My specimen is a basalt slab from the Kuznetsk Basin in southwestern Siberia. The Kuznetsk Basin is also home to one of the largest coal deposits on earth, a remnant of the global destruction caused by the Siberian Traps during the greatest extinction event in the history of the planet.

 

[EnolaGaia]

I own a very small piece of this. My specimen is a basalt slab from the Kuznetsk Basin in southwestern Siberia. The Kuznetsk Basin is also home to one of the largest coal deposits on earth, a remnant of the global destruction caused by the Siberian Traps during the greatest extinction event in the history of the planet.

New research strongly suggests the coal deposits weren't so much the result of the extinction event as its cause ...

Massive Coal Burning Linked to 'Great Dying': The Worst Extinction in Earth's History

The most severe extinction in Earth's history looks to have been preceded and enabled by a colossal coal fire lit by volcanism over 250 million years ago, according to new research.

The Permian-Triassic extinction, also known as the 'Great Dying', constitutes the deadliest of all our planet's mass extinction events. When it took place, approximately 252 million years ago, an estimated 96 percent of marine species were wiped out, alongside 70 percent of terrestrial vertebrates.

What could cause such a sweeping die-off across so many of Earth's creatures? The chief culprit is a giant volcanic event that occurred in the lead-up to the Great Dying; it produced a gargantuan region of volcanic rock in Russia called the Siberian Traps. ...

Exactly how the eruptions caused the extinctions remains unknown, with scientists proposing numerous mechanisms that could have been involved: rising temperatures due to greenhouse gases, thinning ozone levels, volatile chemicals produced by the eruption, and even microbial adaptations.

Of course, many of these hypothetical causes do not contradict one another, and could have acted in tandem to help produce this unprecedentedly deadly event. Now, scientists have found evidence for another piece of the puzzle, and it's one that draws a grim parallel with Earth's situation today. ...

It's long been reasoned that the global warming that coincided with the Permian-Triassic extinction would have involved the combustion of coal, carbonates, and organic-rich shales, producing significant levels of heat-trapping carbon dioxide (CO2) and methane (CH4) in the atmosphere. But finding direct evidence for the chemical ingredients has been harder to come by. ...

FULL STORY: https://www.sciencealert.com/massiv...dying-the-worst-extinction-in-earth-s-history

See Also:

https://scitechdaily.com/coal-burni...used-the-earths-most-severe-extinction-event/

 

[EnolaGaia]

Here are the bibliographic details and summary for the newly published research on burning coal's contribution to the Great Dying.

Field evidence for coal combustion links the 252 Ma Siberian Traps with global carbon disruption
L.T. Elkins-Tanton; S.E. Grasby; B.A. Black; R.V. Veselovskiy; O.H. Ardakani; F. Goodarzi
Geology (2020)
https://doi.org/10.1130/G47365.1

The Permian-Triassic extinction was the most severe in Earth history. The Siberian Traps eruptions are strongly implicated in the global atmospheric changes that likely drove the extinction. A sharp negative carbon isotope excursion coincides within geochronological uncertainty with the oldest dated rocks from the Norilsk section of the Siberian flood basalts. We focused on the voluminous volcaniclastic rocks of the Siberian Traps, relatively unstudied as potential carriers of carbon-bearing gases. Over six field seasons we collected rocks from across the Siberian platform, and we show here the first direct evidence that the earliest eruptions in the southern part of the province burned large volumes of a combination of vegetation and coal. We demonstrate that the volume and composition of organic matter interacting with magmas may explain the global carbon isotope signal and may have significantly driven the extinction.

SOURCE: https://pubs.geoscienceworld.org/gs...ld-evidence-for-coal-combustion-links-the-252

 

[EnolaGaia]

Newly published analyses of relatively recent findings suggests the Great Dying served to clear the decks and stimulate the rise and proliferation of the endothermy (warm-bloodedness) and erect postures that would typify eventual mammals and birds.

Switch to Warm-Bloodedness Triggered by World’s Greatest Mass Extinction

Mammals and birds today are warm-blooded, and this is often taken as the reason for their great success.

University of Bristol paleontologist Professor Mike Benton identifies in the journal Gondwana Research that the ancestors of both mammals and birds became warm-blooded at the same time, some 250 million years ago, in the time when life was recovering from the greatest mass extinction of all time.

... Two main groups of tetrapods survived, the synapsids and archosaurs, including ancestors of mammals and birds respectively.

Paleontologists had identified indications of warm-bloodedness, or technically endothermy, in these Triassic survivors, including evidence for a diaphragm and possible whiskers in the synapsids.

More recently, similar evidence for early origin of feathers in dinosaur and bird ancestors has come to light. In both synapsids and archosaurs of the Triassic, the bone structure shows characteristics of warm-bloodedness.

The evidence that mammal ancestors had hair from the beginning of the Triassic has been suspected for a long time, but the suggestion that archosaurs had feathers from 250 million years ago is new. ...

But a strong hint for this sudden origin of warm-bloodedness in both synapsids and archosaurs at exactly the time of the Permian-Triassic mass extinction was found in 2009. Tai Kubo, then a student studying the Masters in Palaeobiology degree at Bristol and Professor Benton identified that all medium-sized and large tetrapods switched from sprawling to erect posture right at the Permian-Triassic boundary.

Their study was based on fossilized footprints. They looked at a sample of hundreds of fossil trackways, and Kubo and Benton were surprised to see the posture shift happened instantly, not strung out over tens of millions of years, as had been suggested. It also happened in all groups, not just the mammal ancestors or bird ancestors.

Professor Benton said: “Modern amphibians and reptiles are sprawlers, holding their limbs partly sideways.

“Birds and mammals have erect postures, with the limbs immediately below their bodies. This allows them to run faster, and especially further. There are great advantages in erect posture and warm-bloodedness, but the cost is that endotherms have to eat much more than cold-blooded animals just to fuel their inner temperature control.”

The evidence from posture change and from early origin of hair and feathers, all happening at the same time, suggested this was the beginning of a kind of “arms race.” In ecology, arms races occur when predators and prey have to compete with each other, and where there may be an escalation of adaptations. ...

Professor Benton added: “The Triassic was a remarkable time in the history of life on Earth. You see birds and mammals everywhere on land today, whereas amphibians and reptiles are often quite hidden.

“This revolution in ecosystems was triggered by the independent origins of endothermy in birds and mammals, but until recently we didn’t realize that these two events might have been coordinated. ...

FULL STORY: https://scitechdaily.com/switch-to-warm-bloodedness-triggered-by-worlds-greatest-mass-extinction/

 

[EnolaGaia]

Here are the bibliographic details and abstract for the published research report. The full report is accessible at the link below.

The origin of endothermy in synapsids and archosaurs and arms races in the Triassic
Michael J.Benton
Gondwana Research
Available online 3 September 2020
https://doi.org/10.1016/j.gr.2020.08.003

Abstract
Birds and mammals are key elements of modern ecosystems, and many biologists explain their great success by their endothermy, or warm-bloodedness. New palaeontological discoveries point to the origins of endothermy in the Triassic, and that birds (archosaurs) and mammals (synapsids) likely acquired endothermy in parallel. Here, a further case is made, that the emergence of endothermy in a stepwise manner began in the Late Permian but accelerated in the Early Triassic. The trigger was the profound destruction wrought by the Permian-Triassic mass extinction (PTME). In the oceans, this was the beginning of the Mesozoic Marine Revolution (MMR), and a similar revolution occurred on land, termed here the Triassic Terrestrial Revolution (TTR). Among tetrapods, both synapsids and archosaurs survived into the Triassic, but numbers were heavily depleted. However, the survivors were marked by the acquisition of endothermy, as shown by bone histology, isotopic analyses, and the acquisition of insulating pelage. Both groups before the PTME had been sprawlers; after the event they adopted parasagittal (erect) gait. The new posture and the new physiology enabled both groups to compete in their ecosystems at a faster rate than before the PTME. The new world of the Triassic was characterised by a fast-paced arms race between synapsids and archosauromorphs in which the latter, as both dinosaurs and pterosaurs, initially prevailed.

FULL REPORT:
https://www.sciencedirect.com/science/article/pii/S1342937X20302252?via=ihub

 

[EnolaGaia]

Newly published research from a multi-national team has compiled a coherent storyline for how massive vulcanism ended up triggering the Great Dying.

New study provides a comprehensive reconstruction of the Permian-Triassic boundary event.

Life on Earth has a long, but also an extremely turbulent history. On more than one occasion, the majority of all species became extinct and an already highly developed biodiversity shrank to a minimum again, changing the course of evolution each time. The most extensive mass extinction took place about 252 million years ago. It marked the end of the Permian Epoch and the beginning of the Triassic Epoch. About three quarters of all land life and about 95 percent of life in the ocean disappeared within just a few thousands of years.

Gigantic volcanic activities in today’s Siberia and the release of large amounts of methane from the sea floor have been long debated as potential triggers of the Permian-Triassic extinction. But the exact cause and the sequence of events that led to the mass extinction remained highly controversial. Now, scientists from Germany, Italy and Canada ... have for the first time been able to conclusively reconstruct the entire cascade of events at that time using cutting-edge analytical techniques and innovative geochemical modelling. The study has been published today (October 19, 2020) in the international journal Nature Geoscience. ...

FULL STORY: https://scitechdaily.com/driver-ide...-mass-extinction-in-the-history-of-the-earth/

 

[EnolaGaia]

Here are the bibliographic details and abstract from the newly published research ...

Jurikova, H., Gutjahr, M., Wallmann, K. et al.
Permian–Triassic mass extinction pulses driven by major marine carbon cycle perturbations.
Nat. Geosci. (2020).
https://doi.org/10.1038/s41561-020-00646-4

Abstract
The Permian/Triassic boundary approximately 251.9 million years ago marked the most severe environmental crisis identified in the geological record, which dictated the onwards course for the evolution of life. Magmatism from Siberian Traps is thought to have played an important role, but the causational trigger and its feedbacks are yet to be fully understood. Here we present a new boron-isotope-derived seawater pH record from fossil brachiopod shells deposited on the Tethys shelf that demonstrates a substantial decline in seawater pH coeval with the onset of the mass extinction in the latest Permian. Combined with carbon isotope data, our results are integrated in a geochemical model that resolves the carbon cycle dynamics as well as the ocean redox conditions and nitrogen isotope turnover. We find that the initial ocean acidification was intimately linked to a large pulse of carbon degassing from the Siberian sill intrusions. We unravel the consequences of the greenhouse effect on the marine environment, and show how elevated sea surface temperatures, export production and nutrient input driven by increased rates of chemical weathering gave rise to widespread deoxygenation and sporadic sulfide poisoning of the oceans in the earliest Triassic. Our findings enable us to assemble a consistent biogeochemical reconstruction of the mechanisms that resulted in the largest Phanerozoic mass extinction.

SOURCE: https://www.nature.com/articles/s41561-020-00646-4#citeas

 

[EnolaGaia]

Newly reported research indicates the Great Dying occurred ten times more slowly on land than in marine environments. This difference in the extinction process's speed is curious, and its explanation has to await further research.

The full research article is accessible at the final link below.

Earth’s Worst Mass Extinction Took Ten Times Longer on Land Than in the Water

Our planet’s worst mass extinction event happened 252 million years ago when massive volcanic eruptions caused catastrophic climate change. The vast majority of animal species went extinct, and when the dust settled, the planet entered the early days of the Age of Dinosaurs. Scientists are still learning about the patterns of which animals went extinct and which ones survived, and why. In a new study in PNAS, researchers found that while extinctions happened rapidly in the oceans, life on land underwent a longer, more drawn-out period of extinctions.

“People assumed that because the marine extinction happened over a short period of time, life on land should have followed the same pattern, but we found that the marine extinction may actually be a punctuation to a longer, more drawn-out event on land,” says Pia Viglietti, a postdoctoral researcher at Chicago’s Field Museum and the lead author of the PNAS study. ...

Examining fossils like Lystrosaurus showed the researchers that the Permian extinction looked very different on land than it did in the oceans—it was a much longer, more drawn-out affair. Using the earlier comparison, if the history of life on Earth were compressed into a single year and the end-Permian extinction killed 95% of the ocean’s animals in a matter of 14 minutes, the land extinction would have taken ten times as long, about two hours and twenty minutes.

It’s not clear exactly why the mass extinction event happened so much more slowly on land. “The changes to the Earth’s climate were cumulative and added up over time. Ecosystems were slowly disrupted, and then it just got to a point where everything collapsed, like the straw that breaks the camel’s back,” says Viglietti. “Everything’s fine, until it’s not.” ...

FULL STORY: https://scitechdaily.com/earths-wor...k-ten-times-longer-on-land-than-in-the-water/

PUBLISHED RESEARCH REPORT:
Evidence from South Africa for a protracted end-Permian extinction on land
Pia A. Viglietti, Roger B. J. Benson, Roger M. H. Smith, Jennifer Botha, Christian F. Kammerer, et al.
Proceedings of the National Academy of Sciences Apr 2021, 118 (17) e2017045118
DOI: 10.1073/pnas.2017045118

FULL REPORT: https://www.pnas.org/content/118/17/e2017045118

 

[Nosmo King]

Newly reported research indicates the Great Dying occurred ten times more slowly on land than in marine environments. This difference in the extinction process's speed is curious, and its explanation has to await further research.

The full research article is accessible at the final link below.

FULL STORY: https://scitechdaily.com/earths-wor...k-ten-times-longer-on-land-than-in-the-water/

PUBLISHED RESEARCH REPORT:
Evidence from South Africa for a protracted end-Permian extinction on land
Pia A. Viglietti, Roger B. J. Benson, Roger M. H. Smith, Jennifer Botha, Christian F. Kammerer, et al.
Proceedings of the National Academy of Sciences Apr 2021, 118 (17) e2017045118
DOI: 10.1073/pnas.2017045118

FULL REPORT: https://www.pnas.org/content/118/17/e2017045118

Couldit be to do with a more delicate food chain, algea needs to photosynthesise, if that dies the plankton that feed on it dies, then the plankton eaters, then smaller marine animals that eat them and so on until most species die, all because the algae died, on land there isnt this delicate food chain

 

[EnolaGaia]

The marine food chain is (currently) believed to have been disrupted by sulfide poisoning and general deoxygenation. This global fouling of the waters would help explain why the marine environments collapsed so much sooner / faster than the terrestrial ones.

It's too soon to tell to what extent the terrestrial food chains were disrupted and how this may have contributed to the extinctions on land.

 

[EnolaGaia]

The marine food chain is (currently) believed to have been disrupted by sulfide poisoning and general deoxygenation. This global fouling of the waters would help explain why the marine environments collapsed so much sooner / faster than the terrestrial ones. ...

Newly published research and analysis suggests the End Permian Extinction, once triggered, was driven by de-oxygenation of the oceans, accelerated microbial metabolism, and a lot of resultant stinky hydrogen sulfide.

Deadliest Period in Earth’s History Was Also the Stinkiest – Toxic Microbe Burps Caused Mass Extinction

Tiny microbes belching toxic gas helped cause — and prolong — the biggest mass extinction in Earth’s history, a new study suggests.

Generally, scientists believe Siberian volcanos spitting greenhouse gases primarily drove the mass extinction event about 250 million years ago, at the end of the Permian period. The gases caused extreme warming, which in turn led 80% of all marine species, as well as many land species, to go extinct.

Until now, scientists could not explain exactly how the heat caused those deaths. A new UC Riverside-led study in Nature Geoscience shows that the heat accelerated microbes’ metabolisms, creating deadly conditions.

“After oxygen in the ocean was used up to decompose organic material, microbes started to ‘breathe’ sulfate and produced hydrogen sulfide, a gas that smells like rotten eggs and is poisonous to animals,” said UC Riverside Earth system modeler Dominik Hülse.

As ocean photosynthesizers — the microbes and plants that form the base of the food chain — rotted, other microbes quickly consumed the oxygen and left little of it for larger organisms. In the absence of oxygen, microbes consumed sulfate then expelled toxic, reeking hydrogen sulfide, or H2S, creating an even more extreme condition called euxinia. These conditions were sustained by the release of nutrients during decomposition, promoting the production of more organic material which helped to maintain this stinky, toxic cycle. ...

The expanding euxinic zones can be detected through chemical signatures in sediment samples. ...

FULL STORY: https://scitechdaily.com/deadliest-...t-toxic-microbe-burps-caused-mass-extinction/