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Princeton Paleontologist Produces Evidence For New Theory On Dinosaur Extinction
"Ron Baalke" wrote in message ... http://www.princeton.edu/pr/news/03/q3/0925-keller.htm Princeton University Office of Communications 22 Chambers St. Princeton, New Jersey 08542 Telephone 609-258-3601; Fax 609-258-1301 For immediate release: September 25, 2003 Contact: Steven Schultz, (609) 258-5729, Princeton paleontologist produces evidence for new theory on dinosaur extinction PRINCETON, N.J. -- As a paleontologist, Gerta Keller has studied many aspects of the history of life on Earth. But the question capturing her attention lately is one so basic it has passed the lips of generations of 6-year-olds: What killed the dinosaurs? The answers she has been uncovering for the last decade have stirred an adult-sized debate that puts Keller at odds with many scientists who study the question. Keller, a professor in Princeton's Department of Geosciences, is among a minority of scientists who believe that the story of the dinosaurs' demise is much more complicated than the familiar and dominant theory that a single asteroid hit Earth 65 million years ago and caused the mass extinction known as the Cretacious-Tertiary, or K/T, boundary. Keller and a growing number of colleagues around the world are turning up evidence that, rather than a single event, an intensive period of volcanic eruptions as well as a series of asteroid impacts are likely to have stressed the world ecosystem to the breaking point. Although an asteroid or comet probably struck Earth at the time of the dinosaur extinction, it most likely was, as Keller says, "the straw that broke the camel's back" and not the sole cause. Perhaps more controversially, Keller and colleagues contend that the "straw" -- that final impact -- is probably not what most scientists believe it is. For more than a decade, the prevailing theory has centered on a massive impact crater in Mexico. In 1990, scientists proposed that the Chicxulub crater, as it became known, was the remnant of the fateful dinosaur-killing event and that theory has since become dogma. Keller has accumulated evidence, including results released this year, suggesting that the Chicxulub crater probably did not coincide with the K/T boundary. Instead, the impact that caused the Chicxulub crater was likely smaller than originally believed and probably occurred 300,000 years before the mass extinction. The final dinosaur-killer probably struck Earth somewhere else and remains undiscovered, said Keller. These views have not made Keller a popular figure at meteorite impact meetings. "For a long time she's been in a very uncomfortable minority," said Vincent Courtillot, a geological physicist at Université Paris 7. The view that there was anything more than a single impact at work in the mass extinction of 65 million years ago "has been battered meeting after meeting by a majority of very renowned scientists," said Courtillot. The implications of Keller's ideas extend beyond the downfall of ankylosaurus and company. Reviving an emphasis on volcanism, which was the leading hypothesis before the asteroid theory, could influence the way scientists think about the Earth's many episodes of greenhouse warming, which mostly have been caused by periods of volcanic eruptions. In addition, if the majority of scientists eventually reduce their estimates of the damage done by a single asteroid, that shift in thinking could influence the current-day debate on how much attention should be given to tracking and diverting Earth-bound asteroids and comets in the future. Keller does not work with big fossils such as dinosaur bones commonly associated with paleontology. Instead, her expertise is in one-celled organisms, called foraminifera, which pervade the oceans and evolved rapidly through geologic periods. Some species exist for only a couple hundred thousand years before others replace them, so the fossil remains of short-lived species constitute a timeline by which surrounding geologic features can be dated. In a series of field trips to Mexico and other parts of the world, Keller has accumulated several lines of evidence to support her view of the K/T extinction. She has found, for example, populations of pre-K/T foraminifera that lived on top of the impact fallout from Chicxulub. (The fallout is visible as a layer of glassy beads of molten rock that rained down after the impact.) These fossils indicate that this impact came about 300,000 years before the mass extinction. The latest evidence came last year from an expedition by an international team of scientists who drilled 1,511 meters into the Chicxulub crater looking for definitive evidence of its size and age. Although interpretations of the drilling samples vary, Keller contends that the results contradict nearly every established assumption about Chicxulub and confirm that the Cretaceous period persisted for 300,000 years after the impact. In addition, the Chicxulub crater appears to be much smaller than originally thought -- less than 120 kilometers in diameter compared with the original estimates of 180 to 300 kilometers. Keller and colleagues are now studying the effects of powerful volcanic eruptions that began more than 500,000 years before the K/T boundary and caused a period of global warming. At sites in the Indian Ocean, Madagascar, Israel and Egypt, they are finding evidence that volcanism caused biotic stress almost as severe as the K/T mass extinction itself. These results suggest that asteroid impacts and volcanism may be hard to distinguish based on their effects on plant and animal life and that the K/T mass extinction could be the result of both, said Keller. Note: A longer version of this news release appeared in the Princeton Weekly Bulletin: http://www.princeton.edu/pr/pwb/03/0922/ This is essentially what I've been saying all along. |
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Princeton Paleontologist Produces Evidence For New Theory On Dinosaur Extinction
"George" wrote in message .. . "Ron Baalke" wrote in message ... http://www.princeton.edu/pr/news/03/q3/0925-keller.htm Princeton University Office of Communications 22 Chambers St. Princeton, New Jersey 08542 Telephone 609-258-3601; Fax 609-258-1301 For immediate release: September 25, 2003 Contact: Steven Schultz, (609) 258-5729, Princeton paleontologist produces evidence for new theory on dinosaur extinction PRINCETON, N.J. -- As a paleontologist, Gerta Keller has studied many aspects of the history of life on Earth. But the question capturing her attention lately is one so basic it has passed the lips of generations of 6-year-olds: What killed the dinosaurs? The answers she has been uncovering for the last decade have stirred an adult-sized debate that puts Keller at odds with many scientists who study the question. Keller, a professor in Princeton's Department of Geosciences, is among a minority of scientists who believe that the story of the dinosaurs' demise is much more complicated than the familiar and dominant theory that a single asteroid hit Earth 65 million years ago and caused the mass extinction known as the Cretacious-Tertiary, or K/T, boundary. Keller and a growing number of colleagues around the world are turning up evidence that, rather than a single event, an intensive period of volcanic eruptions as well as a series of asteroid impacts are likely to have stressed the world ecosystem to the breaking point. Although an asteroid or comet probably struck Earth at the time of the dinosaur extinction, it most likely was, as Keller says, "the straw that broke the camel's back" and not the sole cause. Perhaps more controversially, Keller and colleagues contend that the "straw" -- that final impact -- is probably not what most scientists believe it is. For more than a decade, the prevailing theory has centered on a massive impact crater in Mexico. In 1990, scientists proposed that the Chicxulub crater, as it became known, was the remnant of the fateful dinosaur-killing event and that theory has since become dogma. Keller has accumulated evidence, including results released this year, suggesting that the Chicxulub crater probably did not coincide with the K/T boundary. Instead, the impact that caused the Chicxulub crater was likely smaller than originally believed and probably occurred 300,000 years before the mass extinction. The final dinosaur-killer probably struck Earth somewhere else and remains undiscovered, said Keller. These views have not made Keller a popular figure at meteorite impact meetings. "For a long time she's been in a very uncomfortable minority," said Vincent Courtillot, a geological physicist at Université Paris 7. The view that there was anything more than a single impact at work in the mass extinction of 65 million years ago "has been battered meeting after meeting by a majority of very renowned scientists," said Courtillot. The implications of Keller's ideas extend beyond the downfall of ankylosaurus and company. Reviving an emphasis on volcanism, which was the leading hypothesis before the asteroid theory, could influence the way scientists think about the Earth's many episodes of greenhouse warming, which mostly have been caused by periods of volcanic eruptions. In addition, if the majority of scientists eventually reduce their estimates of the damage done by a single asteroid, that shift in thinking could influence the current-day debate on how much attention should be given to tracking and diverting Earth-bound asteroids and comets in the future. Keller does not work with big fossils such as dinosaur bones commonly associated with paleontology. Instead, her expertise is in one-celled organisms, called foraminifera, which pervade the oceans and evolved rapidly through geologic periods. Some species exist for only a couple hundred thousand years before others replace them, so the fossil remains of short-lived species constitute a timeline by which surrounding geologic features can be dated. In a series of field trips to Mexico and other parts of the world, Keller has accumulated several lines of evidence to support her view of the K/T extinction. She has found, for example, populations of pre-K/T foraminifera that lived on top of the impact fallout from Chicxulub. (The fallout is visible as a layer of glassy beads of molten rock that rained down after the impact.) These fossils indicate that this impact came about 300,000 years before the mass extinction. The latest evidence came last year from an expedition by an international team of scientists who drilled 1,511 meters into the Chicxulub crater looking for definitive evidence of its size and age. Although interpretations of the drilling samples vary, Keller contends that the results contradict nearly every established assumption about Chicxulub and confirm that the Cretaceous period persisted for 300,000 years after the impact. In addition, the Chicxulub crater appears to be much smaller than originally thought -- less than 120 kilometers in diameter compared with the original estimates of 180 to 300 kilometers. Keller and colleagues are now studying the effects of powerful volcanic eruptions that began more than 500,000 years before the K/T boundary and caused a period of global warming. At sites in the Indian Ocean, Madagascar, Israel and Egypt, they are finding evidence that volcanism caused biotic stress almost as severe as the K/T mass extinction itself. These results suggest that asteroid impacts and volcanism may be hard to distinguish based on their effects on plant and animal life and that the K/T mass extinction could be the result of both, said Keller. Note: A longer version of this news release appeared in the Princeton Weekly Bulletin: http://www.princeton.edu/pr/pwb/03/0922/ This is essentially what I've been saying all along. I hope everyone reads the longer version of this carefully deited press release it contains one of the absolutely hilarious statements I've seen about a scientific discovery since cold fusion: In other studies spread across a range of excavation sites, Keller has found evidence that the ecological disruption caused by the Chicxulub impact may not have been as severe as originally thought. She found normal marine sediments lying directly on top of the fallout layer, suggesting that there were no tsunami waves or other major disturbances. Let me get this straight, an impact that caused a crater of less than 120km diameter didn't cause any tidal waves? I hope this conclusion was drawn by some PR guy and not by someone associated with the actual research. Ken |
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Princeton Paleontologist Produces Evidence For New Theory On Dinosaur Extinction
"Ken Shaw" wrote in message ... "George" wrote in message .. . "Ron Baalke" wrote in message ... http://www.princeton.edu/pr/news/03/q3/0925-keller.htm Princeton University Office of Communications 22 Chambers St. Princeton, New Jersey 08542 Telephone 609-258-3601; Fax 609-258-1301 For immediate release: September 25, 2003 Contact: Steven Schultz, (609) 258-5729, Princeton paleontologist produces evidence for new theory on dinosaur extinction PRINCETON, N.J. -- As a paleontologist, Gerta Keller has studied many aspects of the history of life on Earth. But the question capturing her attention lately is one so basic it has passed the lips of generations of 6-year-olds: What killed the dinosaurs? The answers she has been uncovering for the last decade have stirred an adult-sized debate that puts Keller at odds with many scientists who study the question. Keller, a professor in Princeton's Department of Geosciences, is among a minority of scientists who believe that the story of the dinosaurs' demise is much more complicated than the familiar and dominant theory that a single asteroid hit Earth 65 million years ago and caused the mass extinction known as the Cretacious-Tertiary, or K/T, boundary. Keller and a growing number of colleagues around the world are turning up evidence that, rather than a single event, an intensive period of volcanic eruptions as well as a series of asteroid impacts are likely to have stressed the world ecosystem to the breaking point. Although an asteroid or comet probably struck Earth at the time of the dinosaur extinction, it most likely was, as Keller says, "the straw that broke the camel's back" and not the sole cause. Perhaps more controversially, Keller and colleagues contend that the "straw" -- that final impact -- is probably not what most scientists believe it is. For more than a decade, the prevailing theory has centered on a massive impact crater in Mexico. In 1990, scientists proposed that the Chicxulub crater, as it became known, was the remnant of the fateful dinosaur-killing event and that theory has since become dogma. Keller has accumulated evidence, including results released this year, suggesting that the Chicxulub crater probably did not coincide with the K/T boundary. Instead, the impact that caused the Chicxulub crater was likely smaller than originally believed and probably occurred 300,000 years before the mass extinction. The final dinosaur-killer probably struck Earth somewhere else and remains undiscovered, said Keller. These views have not made Keller a popular figure at meteorite impact meetings. "For a long time she's been in a very uncomfortable minority," said Vincent Courtillot, a geological physicist at Université Paris 7. The view that there was anything more than a single impact at work in the mass extinction of 65 million years ago "has been battered meeting after meeting by a majority of very renowned scientists," said Courtillot. The implications of Keller's ideas extend beyond the downfall of ankylosaurus and company. Reviving an emphasis on volcanism, which was the leading hypothesis before the asteroid theory, could influence the way scientists think about the Earth's many episodes of greenhouse warming, which mostly have been caused by periods of volcanic eruptions. In addition, if the majority of scientists eventually reduce their estimates of the damage done by a single asteroid, that shift in thinking could influence the current-day debate on how much attention should be given to tracking and diverting Earth-bound asteroids and comets in the future. Keller does not work with big fossils such as dinosaur bones commonly associated with paleontology. Instead, her expertise is in one-celled organisms, called foraminifera, which pervade the oceans and evolved rapidly through geologic periods. Some species exist for only a couple hundred thousand years before others replace them, so the fossil remains of short-lived species constitute a timeline by which surrounding geologic features can be dated. In a series of field trips to Mexico and other parts of the world, Keller has accumulated several lines of evidence to support her view of the K/T extinction. She has found, for example, populations of pre-K/T foraminifera that lived on top of the impact fallout from Chicxulub. (The fallout is visible as a layer of glassy beads of molten rock that rained down after the impact.) These fossils indicate that this impact came about 300,000 years before the mass extinction. The latest evidence came last year from an expedition by an international team of scientists who drilled 1,511 meters into the Chicxulub crater looking for definitive evidence of its size and age. Although interpretations of the drilling samples vary, Keller contends that the results contradict nearly every established assumption about Chicxulub and confirm that the Cretaceous period persisted for 300,000 years after the impact. In addition, the Chicxulub crater appears to be much smaller than originally thought -- less than 120 kilometers in diameter compared with the original estimates of 180 to 300 kilometers. Keller and colleagues are now studying the effects of powerful volcanic eruptions that began more than 500,000 years before the K/T boundary and caused a period of global warming. At sites in the Indian Ocean, Madagascar, Israel and Egypt, they are finding evidence that volcanism caused biotic stress almost as severe as the K/T mass extinction itself. These results suggest that asteroid impacts and volcanism may be hard to distinguish based on their effects on plant and animal life and that the K/T mass extinction could be the result of both, said Keller. Note: A longer version of this news release appeared in the Princeton Weekly Bulletin: http://www.princeton.edu/pr/pwb/03/0922/ This is essentially what I've been saying all along. I hope everyone reads the longer version of this carefully deited press release it contains one of the absolutely hilarious statements I've seen about a scientific discovery since cold fusion: In other studies spread across a range of excavation sites, Keller has found evidence that the ecological disruption caused by the Chicxulub impact may not have been as severe as originally thought. She found normal marine sediments lying directly on top of the fallout layer, suggesting that there were no tsunami waves or other major disturbances. Let me get this straight, an impact that caused a crater of less than 120km diameter didn't cause any tidal waves? I hope this conclusion was drawn by some PR guy and not by someone associated with the actual research. Ken If she found undisturbed strata directly above the fallout layer, what is your interpretation? Please note, she didn't make a conclusion, she only stated that it *suggested* that "no tsunami waves or other major disturbances" occurred. It is her interpretation of the data, which she, as author of the report, is entitled to do. If you think she is wrong, by all means, go out there and collect the data, and prove her wrong. That's what science is all about, is it not? |
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Princeton Paleontologist Produces Evidence For New Theory On Dinosaur Extinction
Normal Georges ! ...since you are such a clueless Gogologist ...like the
others by the way ! -- Jean-Paul Turcaud Hydro & Mining Prospector Discoverer of Telfer; Kintyre & Nifty Mines-Great Sandy Desert. Discoverer of the South Atlantic Submarine Gold Placers ( 40 Millions Tons estimate ) Founder of the TRUE GEOLOGY ~~Ignorance Is The Cosmic Sin, The One Never Forgiven ! ~~ "George" a écrit dans le message de .. . This is essentially what I've been saying all along. |
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Princeton Paleontologist Produces Evidence For New Theory On Dinosaur Extinction
Thanks Ken !
Someone at least having retained some of his god-given free will ! Congratulations my friend ! -- Jean-Paul Turcaud Hydro & Mining Prospector Discoverer of Telfer; Kintyre & Nifty Mines-Great Sandy Desert. Discoverer of the South Atlantic Submarine Gold Placers ( 40 Millions Tons estimate ) Founder of the TRUE GEOLOGY ~~Ignorance Is The Cosmic Sin, The One Never Forgiven ! ~~ "Ken Shaw" a écrit dans le message de ... In other studies spread across a range of excavation sites, Keller has found evidence that the ecological disruption caused by the Chicxulub impact may not have been as severe as originally thought. She found normal marine sediments lying directly on top of the fallout layer, suggesting that there were no tsunami waves or other major disturbances. Let me get this straight, an impact that caused a crater of less than 120km diameter didn't cause any tidal waves? I hope this conclusion was drawn by some PR guy and not by someone associated with the actual research. Ken |
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Princeton Paleontologist Produces Evidence For New Theory On Dinosaur Extinction
"George" wrote in message ... That's what science is all about, is it not? Quite right George, to me it looks like Gerta is doing science and not spouting dogma like others. |
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Princeton Paleontologist Produces Evidence For New Theory On Dinosaur Extinction
"AliCat" wrote in message ... "George" wrote in message ... That's what science is all about, is it not? Quite right George, to me it looks like Gerta is doing science and not spouting dogma like others. Well, it obviously what she is doing is controversial. But no less so than the impact hypothesis itself. |
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Princeton Paleontologist Produces Evidence For New Theory OnDinosaur Extinction
George wrote:
"Ken Shaw" wrote in message ... "George" wrote in message .. . (BIG SNIP) I hope everyone reads the longer version of this carefully deited press release it contains one of the absolutely hilarious statements I've seen about a scientific discovery since cold fusion: In other studies spread across a range of excavation sites, Keller has found evidence that the ecological disruption caused by the Chicxulub impact may not have been as severe as originally thought. She found normal marine sediments lying directly on top of the fallout layer, suggesting that there were no tsunami waves or other major disturbances. Let me get this straight, an impact that caused a crater of less than 120km diameter didn't cause any tidal waves? I hope this conclusion was drawn by some PR guy and not by someone associated with the actual research. Ken If she found undisturbed strata directly above the fallout layer, what is your interpretation? Please note, she didn't make a conclusion, she only stated that it *suggested* that "no tsunami waves or other major disturbances" occurred. It is her interpretation of the data, which she, as author of the report, is entitled to do. If you think she is wrong, by all means, go out there and collect the data, and prove her wrong. That's what science is all about, is it not? The way I look at it, the tsunamis generated by the impact could easily have washed their way around the world and done their work of disturbing the sediments *before* the fallout made it back down into the atmosphere and thru the water down to the seafloor. Plus, you're not going to have sediments disturbed in deep enough water (no, I don't know what the exact depth would be) even by a really *BIG* tsunami. Hence no disturbances in the sediments above or below the fallout layer. Jim -- ************************************************** ** ** Facilior veniam posterius quam prius capere! ** ************************************************** ** ** James F. Cornwall, sole owner of all opinions ** ** expressed in this message... ** ************************************************** ** |
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Princeton Paleontologist Produces Evidence For New Theory On Dinosaur Extinction
On Thu, 25 Sep 2003 21:52:19 GMT, "Ken Shaw"
wrote: I hope everyone reads the longer version of this carefully deited press release it contains one of the absolutely hilarious statements I've seen about a scientific discovery since cold fusion: In other studies spread across a range of excavation sites, Keller has found evidence that the ecological disruption caused by the Chicxulub impact may not have been as severe as originally thought. She found normal marine sediments lying directly on top of the fallout layer, suggesting that there were no tsunami waves or other major disturbances. Let me get this straight, an impact that caused a crater of less than 120km diameter didn't cause any tidal waves? I hope this conclusion was drawn by some PR guy and not by someone associated with the actual research. In detail, the K-T boundary does not show a perfect picture of K strata overlain by *one* Ir-, Pd-, and spherule-rich impact layer, which, in turn, underlies T strata. More often than not, the boundary includes several layers with impact- and/or ejecta-related signatures, whose age is not always well constrained. Many argue that the occurrence of multiple spherule layers at the K-T boundary is the result of reworking of one original layer, which was subsequently disturbed and redeposited by catastrophic slumps, slides, submarine flows, and tsunami waves associated with the Chicxulub impact. If the above scenario is true, the fact that K-T boundary layer(s) does not have exactly the same age everywhere is not troubling: reworking also means that age determination based on fossils is not reliable. Thus, if one finds a spherule layer underlying, for example, a tsunami deposits, that layer could be assigned to the K-T boundary based on the assumption that the tsunami wave was triggered by the Chicxulub impact. Is that correct? No, says Keller, because the layers present at the K-T boundary are not all the result of reworking, and some of them are actually related to different impact events. And she points out an outcrop in Mexico where 2- to 8-meter thick, tsunami-interpreted deposits overlie a unit with two spherule layers, and she shows that the "tsunami" sandstone actually includes several separated horizons of bioturbation. Ergo, no tsunami wave and no Chicxulub-age for those spherule layers, and, therefore, probably more than one impact. And she is able to test this hypothesis in many other K-T boundary sites. Regards, Mircea |
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