Skip to comments.Recovering From A Mass Extinction
Posted on 01/19/2008 4:13:15 PM PST by blam
Recovering From A Mass Extinction
Fossilised skull of the sabre-toothed Lycaenops, a top predator of the latest Permian. (Credit: Photo by Michael Benton)
ScienceDaily (Jan. 20, 2008) The full recovery of ecological systems, following the most devastating extinction event of all time, took at least 30 million years, according to new research from the University of Bristol.
About 250 million years ago, at the end of the Permian, a major extinction event killed over 90 per cent of life on earth, including insects, plants, marine animals, amphibians, and reptiles. Ecosystems were destroyed worldwide, communities were restructured and organisms were left struggling to recover. This was the nearest life ever came to being completely wiped out.
Previous work indicates that life bounced back quite quickly, but this was mostly in the form of disaster taxa (opportunistic organisms that filled the empty ecospace left behind by the extinction), such as the hardy Lystrosaurus, a barrel-chested herbivorous animal, about the size of a pig.
The most recent research, conducted by Sarda Sahney and Professor Michael Benton at the University of Bristol and recently published in Proceedings of the Royal Society B, indicates that specialised animals forming complex ecosystems, with high biodiversity, complex food webs and a variety of niches, took much longer to recover.
Sahney said: Our research shows that after a major ecological crisis, recovery takes a very long time. So although we have not yet witnessed anything like the level of the extinction that occurred at the end of the Permian, we should nevertheless bear in mind that ecosystems take a very long time to fully recover.
Sahney and Benton looked at the recovery of tetrapods animals with a backbone and four legs, such as amphibians and reptiles and found that although globally tetrapods appeared to recover quickly, the dramatic restructuring that occurred at the community level was not permanent and communities did not recover numerically or ecologically until about 30 million years later.
Professor Benton explained: Diversity is most commonly assessed by tallying the number of taxa on a global scale, but these studies are subject to the vagaries of sampling. By examining well-preserved and well-studied faunas, the taxonomic and ecological recovery of communities after the Permian extinction event can be examined more accurately, and the problems of geological bias are largely avoided.
The Permian extinctions occurred in three waves, the largest being at the boundary between the Permian and Triassic periods, 251 million years ago. This was the most devastating ecological event of all time, thought to be caused by large-scale volcanism in Russia which produced the Siberian Traps, covering over 200,000 square kilometers (77,000 square miles) in lava.
Adapted from materials provided by University of Bristol.
iirc part of a huge crater has been found in what is antarctica (the rest of the crater in theory should be part of the australian plate) which appears to date to this event.
The crater IIRC was far larger than K-T crater/yucatan impact, I will see if I can find the article.
darn FR search will not give me more than one page on any search term, when I click ‘click to show older articles’ it comes up with no matches, sigh.
I found the modified wikipedia entry where this was discussed (added by me, edited later)
“There is no solid evidence of impacts leading to the four other major mass extinctions, though a recent report from Ohio State scientists stated that they have located a 483-km diameter impact crater beneath the East Antarctic Ice Sheet which may date back about 250 million years, based on gravity measurements, which might associate it with the Permian-Triassic extinction event.”
found it, 2 threads
300-mile diameter impact crater.
I thought this was going to an article about conservative candidates in the GOP...
or is it 30-miles wide? sigh the article is not clear.
“The 300-mile-wide crater lies hidden more than a mile beneath the East Antarctic Ice Sheet. And the 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.
Its size and location — in the Wilkes Land region of East Antarctica, south of Australia — also suggest that it could have begun the breakup of the Gondwana supercontinent by creating the tectonic rift that pushed Australia northward.
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 the 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 6 miles wide, while the Wilkes Land meteor could have been up to 30 miles wide — four or five times wider.”
They’re saying that the metor itself may have been 30 miles wide, so a 300-mile-wide crater would not be implausible.
The Cycle of Cosmic Catastrophes:
Flood, Fire, and Famine
in the History of Civilization
by Richard Firestone,
Allen West, and
· Mirabilis · Texas AM Anthropology News · Yahoo Anthro & Archaeo ·
· History or Science & Nature Podcasts · Excerpt, or Link only? · cgk's list of ping lists ·
Hey, I thought we were responsible for the most devastating extinction event of all time... You mean something else topped our record of "thousands of species a day"???
The late Permian was dominated by therapsid (reptiles?), sometimes called ‘mammal-like reptiles’, thought to be the ancestors of mammals, but other reptiles, ancestors to dinosaurs, out-competed our ancestors after the P/T extinction.
Scientists Find Signs of Meteor Crash That Led to Extinctions in Era Before DinosaursDr. Becker, Dr. Poreda and their colleagues had previously found buckyballs at an impact crater in Sudbury, Canada, and in two meteorites. They have also found buckyballs containing similar types of gases in sediments dating from the dinosaur extinctions.
by Kenneth Chang
February 23, 2001
In the experiments, the scientists extracted buckyballs -- not just the typical sphere consisting of 60 carbon atoms, but also larger versions with up to 160 atoms -- from the sediments with organic solvents.
They then opened the buckyballs to release the helium and argon inside them. The nuclei of most helium atoms consist of two protons and two neutrons. A few -- one out of 700,000 helium atoms in the atmosphere -- are a lighter version, with only one neutron. For the helium in the buckyballs, a much larger fraction -- one out of 5,000 -- was the lighter version, similar to the ratio produced by fusion in stars.
The argon indicated a similar story, with low concentrations of a version that is commonly produced on Earth from the radioactive decay of potassium.
"I think the argon isotope ratio measurement is very convincing," said Dr. Kenneth A. Farley, a professor of geochemistry at the California Institute of Technology. "That's very hard to understand if it's not extraterrestrial."
The real question is, how did Karl Rove do it? And why?
What nefarious reason did the Rethulican Master of Minds have to go back into time and wipe out all living things? What was it that had grown up during that time that would have given the DNC an advantage in the next election?
No wonder lefty trolls do this. It’s actually kind of fun trying to think this crap up.
one more like WoofDog’s:
Does a giant crater lie beneath the Antarctic ice?
nature news | 2 06 | Mark Peplow
Posted on 06/05/2006 12:07:10 PM EDT by S0122017
Massive volcano exploded under Antarctic icesheet, study finds
AFP on Yahoo | 1/20/08 | AFP
Posted on 01/20/2008 7:13:34 PM EST by NormsRevenge
Ice Cores Unlock Climate Secrets
BBC | 6-9-2004 | Julianna Kettlewell
Posted on 06/09/2004 6:27:33 PM EDT by blam
Giant asteroid rocked Antarctica
Near Earth Object Information Centre | 8/20/2004 | staff
Posted on 10/18/2004 12:26:51 AM EDT by SunkenCiv
The Eltanin Impact Crater
Geological Society of America | October 27-30, 2002
Christy A. Glatz, Dallas H. Abbott, and Alice A. Nunes
Posted on 10/18/2004 12:46:13 AM EDT by SunkenCiv
Ancient Cataclysm Rearranged Pacific Map, Study Says
National Geographic News | 10-24-2007 | Julian Ryall
Posted on 10/24/2007 5:48:01 PM EDT by blam
Emory paleontologist reports discovery of carnivorous dinosaur tracks in Australia
Emory University | October 19, 2007 | Unknown
Posted on 10/21/2007 10:02:54 AM EDT by decimon
Recovering From A Mass Extinction
Science Daily | 1-20-2008 | University of Bristol
Posted on 01/19/2008 7:13:15 PM EST by blam
[1999 -- The letter of rejection from Nature for the following article is dated August 28, 1968. At the time most earth scientists would not even accept the fact that meteorites regularly impacted the earth. For example, Barringer Crater in Arizona was still thought by many to be of volcanic origin, as well as the craters on the moon. Bob Dietz had just published his work on shatter cones but I wouldn't say that had been generally accepted. There was not even general agreement on sea floor spreading and plate tectonics outside the radical few at Scripps, Woods Hole, and related institutions.]Possible Formation of the Guatemala Basin by the Impact of an Extraterrestrial BodyThe earth must be as frequently cratered per unit area as the moon. By a relative cross section argument, more than 13 times the number of craters the size of the maria on the moon exist, or existed, on the earth. Whether such events occur with sufficient frequency in recent geologic time to provide tangible evidence today of such cratering is uncertain. From the arguments set forth, and the continuing discovery of meteorite craters on the continents (Short, 1966, Baldwin, 1963, Dietz, 1961, and Prouty, 1952) it seems likely that the importance of the effect of extraterrestrial bodies impacting the earth has been, at least, underestimated (the Alverez's hypothesis concerning the end of the dinosaurs by such a mechanism was more than a decade in the future). Certainly there is as much evidence at present to support our hypothesis for the formation of the Guatemala Basin as other hypotheses advanced to explain the low heat flow found in this basin.
by Charles E. Corry and Miller L. Bell
With the tests for shock processes advanced by Short (1966), our hypothesis should be capable of field verification or rejection.
I have always though that the Siberian Trapps may have flowed out of a giant meteor strike. I also had the same thought about the Deccan Trapps in India which were built at the time of the dinosaur extinction. There is some talk of a 400 by 600 mile?/km? crater in that area known as the Shiva crater.
Barren Siberia, Of All Places, May Be Original Home To Animal LifeUF's Joe Meert and KU's Bruce Lieberman concluded that precursors to modern continents began splitting off from a giant supercontinent at the South Pole about 580 million years ago, migrating north toward the equator for about 80 million years. The scientists' analysis suggests that a prominent theory holding that the continents moved far more rapidly is wrong. It also suggests that trilobites, the long-ago forbearers of crabs and lobsters, originated in present-day Siberia when it was a separate continent from Asia and located much farther south... Working independently, the UF and KU geologists each determined that the southern supercontinent began breaking up around 580 million years ago. The separate continents drifted northward toward the equator at about six inches per year, with this relatively rapid movement ending about 500 million years ago, they found... While six inches is fast by comparison to today's continental movement of speed of one to two inches per year, it is far slower than that proposed by another prominent theory on early continental movement. That theory, known to scientists as "inertial interchange true polar wander," held the continents rotated from the South Pole to the equator in a mere 15 million years from 523 million to 505 million years ago - meaning they moved at more than 25 inches per year - more than four times faster than what Lieberman and Meert found.
adapted from materials by Univ of Florida
Thursday, April 8, 2004