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01-24-2005, 04:20 AM
New theory suggest not!
http://www.livescience.com/environm...reat_dying.html
quote:
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Global Warming Likely Cause of Worst Mass Extinction Ever
By Robert Roy Britt
LiveScience Senior Writer
posted: 20 January, 2005
1:20 p.m. ET
Despite some controversial evidence that an asteroid or comet caused the worst mass extinction in history, most researchers now believe a combination of volcanic activity and a warming climate was the cause.
New research announced today further supports this majority view.
The Great Dying, as it is called, occurred 250 million years ago, at the end of the Permian Era. More than 90 percent of all species were wiped out. That much is well documented in the fossil record.
In previous work, scientists led by Luann Becker of the University of California, Santa Barbara claimed evidence for impacts by space rocks in layers of Earth dated to the end-Permian event. Several experts on asteroid impacts have doubted those results, however.
The new study, reported Thursday in the online version of the journal Science, found no evidence for impacts. It indicates the culprit was probably atmospheric warming linked to greenhouse gases from erupting volcanoes.
"Animals and plants both on land and in the sea were dying at the same time, and apparently from the same causes â too much heat and too little oxygen," said University of Washington paleontologist Peter Ward, lead author of the latest paper.
It is the second study in less than two months to reach a similar conclusion.
Ward and his colleagues examined Permian-Triassic vertebrate fossils, including 126 skulls from reptiles and amphibians.
They found evidence for a gradual extinction over about 10 million years leading up to the boundary between the Permian and Triassic periods, then a sharp increase in extinction rate at the boundary that then lasted another 5 million years. That's not what you'd expect from a catastrophic asteroid impact, which theorists say could obliterate a lot of life instantly and set up a global winter that would kill off other species in mere months or years.
A search for material expected to be left by an asteroid or comet impact in the same layers of Earth turned up nothing. If there was an impact, it was a relatively minor contributor to the extinction, Ward's team contends.
The work provides a glimpse of what can happen when the climate heats up over long periods, Ward said.
The evidence for a warming planet back then is pretty solid based on studies of continuous volcanic eruptions in an area known as the Siberian Traps. As the planet warmed, large amounts of frozen methane gas under the ocean might have been released to trigger runaway greenhouse warming, Ward said.
"It appears that atmospheric oxygen levels were dropping at this point also," he said. "If that's true, then high and intermediate elevations would have become uninhabitable. More than half the world would have been unlivable."
Atmospheric oxygen, now at about 21 percent of the content of air at sea level, dropped to around 16 percent during the Great Dying, evidence suggests. The effect would be like trying to breathe atop a 14,000-foot mountain.
"It got hotter and hotter until it reached a critical point and everything died," Ward said. "It was a double-whammy of warmer temperatures and low oxygen, and most life couldn't deal with it."
A study out of the University of Vienna, announced in December, also found no evidence for a large space rock collision near the time of the Great Dying.
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http://www.livescience.com/environm...reat_dying.html
quote:
--------------------------------------------------------------------------------
Global Warming Likely Cause of Worst Mass Extinction Ever
By Robert Roy Britt
LiveScience Senior Writer
posted: 20 January, 2005
1:20 p.m. ET
Despite some controversial evidence that an asteroid or comet caused the worst mass extinction in history, most researchers now believe a combination of volcanic activity and a warming climate was the cause.
New research announced today further supports this majority view.
The Great Dying, as it is called, occurred 250 million years ago, at the end of the Permian Era. More than 90 percent of all species were wiped out. That much is well documented in the fossil record.
In previous work, scientists led by Luann Becker of the University of California, Santa Barbara claimed evidence for impacts by space rocks in layers of Earth dated to the end-Permian event. Several experts on asteroid impacts have doubted those results, however.
The new study, reported Thursday in the online version of the journal Science, found no evidence for impacts. It indicates the culprit was probably atmospheric warming linked to greenhouse gases from erupting volcanoes.
"Animals and plants both on land and in the sea were dying at the same time, and apparently from the same causes â too much heat and too little oxygen," said University of Washington paleontologist Peter Ward, lead author of the latest paper.
It is the second study in less than two months to reach a similar conclusion.
Ward and his colleagues examined Permian-Triassic vertebrate fossils, including 126 skulls from reptiles and amphibians.
They found evidence for a gradual extinction over about 10 million years leading up to the boundary between the Permian and Triassic periods, then a sharp increase in extinction rate at the boundary that then lasted another 5 million years. That's not what you'd expect from a catastrophic asteroid impact, which theorists say could obliterate a lot of life instantly and set up a global winter that would kill off other species in mere months or years.
A search for material expected to be left by an asteroid or comet impact in the same layers of Earth turned up nothing. If there was an impact, it was a relatively minor contributor to the extinction, Ward's team contends.
The work provides a glimpse of what can happen when the climate heats up over long periods, Ward said.
The evidence for a warming planet back then is pretty solid based on studies of continuous volcanic eruptions in an area known as the Siberian Traps. As the planet warmed, large amounts of frozen methane gas under the ocean might have been released to trigger runaway greenhouse warming, Ward said.
"It appears that atmospheric oxygen levels were dropping at this point also," he said. "If that's true, then high and intermediate elevations would have become uninhabitable. More than half the world would have been unlivable."
Atmospheric oxygen, now at about 21 percent of the content of air at sea level, dropped to around 16 percent during the Great Dying, evidence suggests. The effect would be like trying to breathe atop a 14,000-foot mountain.
"It got hotter and hotter until it reached a critical point and everything died," Ward said. "It was a double-whammy of warmer temperatures and low oxygen, and most life couldn't deal with it."
A study out of the University of Vienna, announced in December, also found no evidence for a large space rock collision near the time of the Great Dying.
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01-24-2005, 04:20 PM
01-24-2005, 08:06 PM
I killed the dinosaurs.. Yes I am that old.
OK I lied.
OK I lied.
01-24-2005, 09:29 PM
you are a nut taxi :lol: :lol:
01-24-2005, 09:36 PM
Hahaha I try QQ lol
01-24-2005, 10:39 PM
Taxi, seems noone is interested in dinosaurs..LOL..
01-24-2005, 10:41 PM
No they just don't want to mess with the person who took down all them crazy creatures lol.
Ok I lied again (I'm gettin good at this lol)
It is interesting though..
Posted Tue Jan 25, 2005 1:46 am:
Something I've always wondered about is, the first time God destroyed the world (this is for the Bible believers) he flooded it. Now Noah took two of each animal, and back then people lived for a pretty long time. So you would imagine that the animals did also. Now we know people rarely live to see one hundred, much less 200 and up. So if ya think about it, animals probably have shorter life spans also. Reptiles grow continuously from what I've heard. So you take an alligator that is 2 or 3 hundred years old, that is constantly growing, that would be a pretty big gator. Now what if, when noah took up some animals, he took the smaller ones. Knowing what we know now about shorter life spans, for both animals and humans, who's to say that all of them are extinct, instead of living today, just as smaller creatures. Maybe this doesn't make since, but it could be something to think about.
Ok I lied again (I'm gettin good at this lol)
It is interesting though..
Posted Tue Jan 25, 2005 1:46 am:
Something I've always wondered about is, the first time God destroyed the world (this is for the Bible believers) he flooded it. Now Noah took two of each animal, and back then people lived for a pretty long time. So you would imagine that the animals did also. Now we know people rarely live to see one hundred, much less 200 and up. So if ya think about it, animals probably have shorter life spans also. Reptiles grow continuously from what I've heard. So you take an alligator that is 2 or 3 hundred years old, that is constantly growing, that would be a pretty big gator. Now what if, when noah took up some animals, he took the smaller ones. Knowing what we know now about shorter life spans, for both animals and humans, who's to say that all of them are extinct, instead of living today, just as smaller creatures. Maybe this doesn't make since, but it could be something to think about.
01-24-2005, 11:06 PM
You had me at Hello!!
Taxi you making my brain hurt!! I have to reply to this later..
Taxi you making my brain hurt!! I have to reply to this later..
01-24-2005, 11:07 PM
You just made my brain hurt with the Jerry Maguire quote. lol. Ill be looking forward to the reply lol.
01-24-2005, 11:10 PM
crazytaxidriver Wrote:You just made my brain hurt with the Jerry Maguire quote. lol. Ill be looking forward to the reply lol.
LMAO!!! When the kids quit screaming.. Ill share it with you..
01-24-2005, 11:17 PM
PDT_003
01-25-2005, 02:55 AM
I'm lost on this discussion so I better not get into it...But can I ask you why your brain is hurting from the Jerry Maguire quote? :lol:
01-25-2005, 03:06 AM
taxi,
I dont think that's what the fat kids shirt originally said is it :lol:
I dont think that's what the fat kids shirt originally said is it :lol:
01-25-2005, 04:02 AM
Captain Morgan Wrote:taxi,
I dont think that's what the fat kids shirt originally said is it :lol:
Hahah.. nope lol
Posted Tue Jan 25, 2005 7:04 am:
BlueGrassGirl Wrote:I'm lost on this discussion so I better not get into it...But can I ask you why your brain is hurting from the Jerry Maguire quote? :lol:
Well, I'm not to sure why he threw it in there lol. But I'm not a real smart man. lol
01-26-2005, 06:03 AM
This is totally off-topic but when I seen this thread I thought it read, "Did a STEROID really kill the dinosaurs". I was thinking, dang, Balco has been around a while. :lol: Anyways, very interesting, nobody knows exactly what happened to them, need further evidence? Ask the person who is claiming to know if they were there.
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