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Far More Than A Meteor Killed Dinos, Evidence Suggests
Science Daily ^ | 10-24-2006 | GSA

Posted on 10/25/2006 3:33:16 PM PDT by blam

Source: Geological Society of America
Date: October 24, 2006

Far More Than A Meteor Killed Dinos, Evidence Suggests

There's growing evidence that the dinosaurs and most their contemporaries were not wiped out by the famed Chicxulub meteor impact, according to a paleontologist who says multiple meteor impacts, massive volcanism in India, and climate changes culminated in the end of the Cretaceous Period.

Cottonmouth Creek waterfall over the event deposit with reworked Chicxulub impact spherules. The original Chicxulub ejecta layer was discovered in a yellow clay layer 45 cm below the base of the event deposit. The yellow clay represents a cheto smectite clay consisting of altered Chicxulub impact glass spherules. (Image courtesy of Geological Society of America)

The Chicxulub impact may, in fact, have been the lesser and earlier of a series of meteors and volcanic eruptions that pounded life on Earth for more than 500,000 years, say Princeton University paleontologist Gerta Keller and her collaborators Thierry Adatte from the University of Neuchatel, Switzerland, and Zsolt Berner and Doris Stueben from Karlsruhe University in Germany. A final, much larger and still unidentified impact 65.5 million years ago appears to have been the last straw, exterminating two thirds of all species in one of the largest mass extinction events in the history of life. It's that impact -- not Chicxulub -- which left the famous extraterrestrial iridium layer found in rocks worldwide that marks the impact that finally ended the Age of Reptiles.

"The Chicxulub impact could not have caused the mass extinction," says Princeton University paleontologist Gerta Keller, "because this impact predates the mass extinction and apparently didn't cause any extinctions."

Keller is scheduled to present that evidence at the Annual Meeting of the Geological Society of America in Philadelphia, 22-25 October. The results of her research, which was funded by the National Science Foundation, will be discussed in two technical sessions and a public lecture sponsored by the Philadelphia Geological Survey.

Marine sediments drilled from the Chicxulub crater itself, as well as from a site in Texas along the Brazos River, and from outcrops in northeastern Mexico reveal that Chicxulub hit Earth 300,000 years before the mass extinction. Small marine animal microfossils were left virtually unscathed, says Keller.

"In all these localities we can analyze the marine microfossils in the sediments directly above and below the Chicxulub impact layer and cannot find any significant biotic effect," said Keller. "We cannot attribute any specific extinctions to this impact." No one has ever published this critical survival story before, she said. Keller's research was funded by the National Science Foundation.

The story that seems to be taking shape is that Chicxulub, though violent, actually conspired with the prolonged and gigantic eruptions of the Deccan Flood Basalts in India, as well as with climate change, to nudge species towards the brink. They were then shoved over with a second large impact.

The Deccan volcanism did the nudging by releasing vast amount of greenhouse gases into the atmosphere over a period of more than a million years leading up tothe mass extinction. By the time Chicxulub struck, the oceans were already 3-4 degrees warmer, even at the bottom, she says.

"On land it must have been 7-8 degrees warmer," says Keller. "This greenhouse warming is well documented. The temperature rise was rapid, over about 20,000 years, and it stayed warm for about100,000 years, then cooled back to normal well before the mass extinction."

Marine species at the time suffered from the heat. Most adapted to the stress conditions by dwarfing, growing less than half their normal size and reproducing rapidly with many offspring to increase the chances for survival. The Chicxulub impact coincided with this time. By the time climate cooled back to normal, most tropical species were on the brink of extinction. Then the second large impact hit and pushed them over the brink -- many straight to extinction.

As for how the dinosaurs were affected, that's a bit harder to say specifically, since dinosaurs did not leave a lot of fossils behind to tell the tale.

"Dinosaur fossils are few and far between," Keller said. "People love the dinosaurs but we can only really study what happened to them by looking at microfossils because these little critters are everywhere at all times. In just a pinch of sediment we can tell you the age, the prevailing climate, the environment in which it was deposited and what happened. It's remarkable."

What the microfossils are saying is that Chicxulub probably aided the demise of the dinosaurs, but so did Deccan trap volcanism's greenhouse warming effect and finally a second huge impact that finished them off. So where's the crater?

"I wish I knew," said Keller. "There is some evidence that it may have hit in India, where a crater of about 500 kilometers in diameter is estimated and named Shiva by paleontologist Sankar Chatterjee from the Museum of Texas Tech University in Lubbock. The evidence for it, however, is not very compelling at this time."


TOPICS: News/Current Events
KEYWORDS: catastrophism; chicxulub; crevolist; deccantraps; dinos; dinosaur; dinosaurs; fallscounty; gertakeller; godsgravesglyphs; killed; meteor; paleontology; sciencewrongagain; volcanism
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1 posted on 10/25/2006 3:33:17 PM PDT by blam
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To: SunkenCiv

GGG Ping?


2 posted on 10/25/2006 3:34:09 PM PDT by blam
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To: blam

I'm sticking with the flood idea...hehehe


3 posted on 10/25/2006 3:35:03 PM PDT by DonaldC
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To: blam

I always thought it was Doug McClure with a spear.


4 posted on 10/25/2006 3:35:37 PM PDT by pissant
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To: blam

it was emission from pre-historic SUV's (known as mammoths and the large amounts of methane they released, as well as they took up the da*n smokin habit)...


5 posted on 10/25/2006 3:35:43 PM PDT by GeorgiaDawg32 (At 53, I'm the life of every party I go to, even if it lasts till 8 p.m...)
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To: DonaldC

Agree, why more people can't take the Bible literally and come to the conclusion that a world-wide flood killed the dinosaurs is beyond me.


6 posted on 10/25/2006 3:37:01 PM PDT by pctech
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To: pissant

nah, it was rachal..she made them stop in their tracks so the hunter/gatherers could get to them..

one dino to another: DAMMIT, WHY can't OUR females look like that??


7 posted on 10/25/2006 3:37:04 PM PDT by GeorgiaDawg32 (At 53, I'm the life of every party I go to, even if it lasts till 8 p.m...)
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To: blam

Makes sense. Any one event is probably not enough to cause a worldwide mass extinction -- unless it comes at just the worst possible time because of other events which happen to be taking place at the same time and already putting a strain on the ecosystems. In that situation, it'd be the last straw, but all the events would be contributing factors.


8 posted on 10/25/2006 3:37:07 PM PDT by Ichneumon (Ignorance is curable, but the afflicted has to want to be cured.)
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To: blam

hi


9 posted on 10/25/2006 3:37:45 PM PDT by CHICAGOFARMER (12 TH GENERATION PATRIOT.)
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To: pctech
Agree, why more people can't take the Bible literally and come to the conclusion that a world-wide flood killed the dinosaurs is beyond me.

Because all the real-world evidence contradicts that hypothesis.

10 posted on 10/25/2006 3:37:51 PM PDT by Ichneumon (Ignorance is curable, but the afflicted has to want to be cured.)
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To: blam

Global warming; who would have guessed?


11 posted on 10/25/2006 3:40:08 PM PDT by Old Professer (The critic writes with rapier pen, dips it twice, and writes again.)
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To: blam
There's growing evidence that the dinosaurs and most their contemporaries were not wiped out by the famed Chicxulub meteor impact, according to a paleontologist who says multiple meteor impacts, massive volcanism in India, and climate changes culminated in the end of the Cretaceous Period.

(Gen 7:10 KJV) And it came to pass after seven days, that the waters of the flood were upon the earth.

(Gen 7:11 KJV) In the six hundredth year of Noah's life, in the second month, the seventeenth day of the month, the same day were all the fountains of the great deep broken up, and the windows of heaven were opened.

12 posted on 10/25/2006 3:41:00 PM PDT by RaceBannon (Innocent until proven guilty: The Pendleton 8)
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To: GeorgiaDawg32

We know it wasn't Ringo Starr.


13 posted on 10/25/2006 3:41:19 PM PDT by pissant
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To: blam
For the real reason dinosaurs became extinct, click here....
14 posted on 10/25/2006 3:41:20 PM PDT by mewzilla (Property must be secured or liberty cannot exist. John Adams)
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To: Old Professer

You mean it wasn't from smoking?


15 posted on 10/25/2006 3:41:20 PM PDT by dfwgator
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To: dfwgator

Hee hee, great minds....


16 posted on 10/25/2006 3:42:04 PM PDT by mewzilla (Property must be secured or liberty cannot exist. John Adams)
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To: blam

I know I'm beat BUT
.
.
.
BLAME BUSH


17 posted on 10/25/2006 3:42:53 PM PDT by IrishMike (Democrats .... Stuck on Stupid, RINO's ...the most vicious judas goats)
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To: dfwgator

Maybe the secondhand smoke from the volcano...


18 posted on 10/25/2006 3:43:04 PM PDT by Old Professer (The critic writes with rapier pen, dips it twice, and writes again.)
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To: GeorgiaDawg32

19 posted on 10/25/2006 3:44:12 PM PDT by magslinger (If at first you don't succeed, squeeze, squeeze again.)
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To: magslinger

Thank you!!!


20 posted on 10/25/2006 3:44:39 PM PDT by dfwgator
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