Scientist: ONE IMPACT ONLY (Yucatan) Killed Off Dinosaurs

Red Orbit ^ | 11/28/2006 | Staff Writer

[Al Simmons]

Data supports the single-impact theory in a controversial discussion

COLUMBIA, Mo. – The dinosaurs, along with the majority of all other animal species on Earth, went extinct approximately 65 million years ago. Some scientists have said that the impact of a large meteorite in the Yucatan Peninsula, in what is today Mexico, caused the mass extinction, while others argue that there must have been additional meteorite impacts or other stresses around the same time.

A new study provides compelling evidence that "one and only one impact" caused the mass extinction, according to a University of Missouri-Columbia researcher.

"The samples we found strongly support the single impact hypothesis," said Ken MacLeod, associate professor of geological sciences at MU and lead investigator of the study. "Our samples come from very complete, expanded sections without deposits related to large, direct effects of the impact – for example, landslides – that can shuffle the record, so we can resolve the sequence of events well. What we see is a unique layer composed of impact-related material precisely at the level of the disappearance of many species of marine plankton that were contemporaries of the youngest dinosaurs. We do not find any sedimentological or geochemical evidence for additional impacts above or below this level, as proposed in multiple impact scenarios."

MacLeod and his co-investigators studied sediment recovered from the Demerara Rise in the Atlantic Ocean northeast of South America, about 4,500 km (approximately 2,800 miles) from the impact site on the Yucatan Peninsula. Sites closer to and farther from the impact site have been studied, but few intermediary sites such as this have been explored.

Interpretation of samples from locations close to the crater are complicated by factors such as waves, earthquakes and landslides that likely followed the impact and would have reworked the sediment. Samples from farther away received little impact debris and often don’t demonstrably contain a complete record of the mass extinction interval. The Demerara Rise samples, thus, provide an unusually clear picture of the events at the time of the mass extinction.

"With our samples, there just aren’t many complications to confuse interpretation. You could say that you’re looking at textbook quality samples, and the textbook could be used for an introductory class," MacLeod said. "It’s remarkable the degree to which our samples follow predictions given a mass extinction caused by a single impact. Sedimentological and paleontological complexities are minor, the right aged-material is present, and there is no support for multiple impacts or other stresses leading up to or following the deposition of material from the impact."

The impact of a meteorite on the Yucatan Peninsula likely caused massive earthquakes and tsunamis. Dust from the impact entered the atmosphere and blocked sunlight, causing plants to die and animals to lose important sources of food. Temperatures probably cooled significantly around the globe before warming in the following centuries, wildfires on an unprecedented scale may have burned and acid rain might have poured down.

MacLeod and many other scientists believe that these effects led to the relatively rapid extinction of most species on the planet. Some other scientists have argued that a single impact could not have caused the changes observed and say that the impact in the Yucatan predates the mass extinction by 300,000 years.

MacLeod’s co-investigators were Donna L. Whitney from the University of Minnesota, Brian T. Huber from the Smithsonian National Museum of Natural History and Christian Koeberl of the University of Vienna. The study was recently published in the ‘in press’ section of the online version of the Geological Society of America Bulletin. Funding was provided by the U.S. Science Support Program, the U.S. National Science Foundation and the Austrian Science Foundation. Samples were recovered on Leg 207 of the Ocean Drilling Program.

[Al Simmons]

Read this and it might change your mind:

http://www.exodus2006.com/fires.htm

[LiteKeeper]

YEC INTREP

[stormer]

"When I was in college there were still articles suggesting volcanic activity caused the dinosaur extinction."

Oh yeah? Well, when I was in college there were articles suggesting that dragon remains could be found sticking out of the ground in certain places and that the world wasn't flat. So I've got you beat.

[SunkenCiv]

Thanks, ConservativeMind!

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[akorahil]

...no I mean it was Dino's for not buying insurance....yeah that's it

Frank, Peter, Joey, and Sammy hardest hit...

[RetiredArmy]

THIS IS PURE B.S. Everyone, and I mean EVERYONE KNOWS that an impact did not kill off all the TRex's. It waz THEM SUV'S!!! SUV'S I TELL YOU. SUV'S DID IT. The Dims said so.

[SmartAZ]

Dinosaurs were extincted, but frogs were not. Frogs were there, and we still have them. The impact theory does not explain why dinosaurs died and frogs didn't. It also doesn't explain why most plants before that time were gymnosperms and most plants since then are angiosperms.

[VeniVidiVici]

ONE IMPACT ONLY

[SunkenCiv]

Thanks, I love that one.

[SunkenCiv]

Al Simmons: Further confirmation of what all the evidence pointed to anyhow....

and

Lunatic Fringe: The possibility of two earth-shaking meteors that close are pretty remote, and if it did happen it was probably a split rock.

and

blam: Yup. I never paid much attention to the other arguments

Well put. Okay, actually, I have paid attention to other arguments, but none of them held water, and were really just shrieks on the retreat. The impact denial camp has been getting a bit more publicity lately, and will be around for a while yet because they're tied in with the global warming crap, and because sudden extinction by deux ex machina (okay, used that phrase twice in a week) screws up diehard gradualists. I don't mind that they're diehards, just as long as they actually die. ;')

[SunkenCiv]

Welcome to FR.

[wodinoneeye]

Now thats 'Climate Change'.....


But then like everything else :

ITS BUSH'S FAULT *shriek* *shriek* !!!!!

[-=SoylentSquirrel=-]

"...It also doesn't explain why most plants before that time were gymnosperms and most plants since then are angiosperms...."

Hey Hey, keep it clean, you potty mouth!

I understand that the meteor impact site is near or at the location of the present day Mexican state of Quintana Roo.

Nothing to add, I just wanted to say "Quintana Roo".

[Al Simmons]

This might help you to understand why some critters survived K-T and most did not.

http://www.exodus2006.com/fires.htm

[null and void]

The ozone hole grew to an enormous size, and greenhouse gases such as carbon dioxide and water vapor were introduced into the atmosphere without any regulatory oversight. HIV/AIDS and other diseases of the immune system may have been rampant as well. Homelessness was widespread, as was a lack of affordable health insurance.

Ah. So this was during a Republican administration, was it?

[null and void]

Clickable link:
http://www.exodus2006.com/fires.htm

[null and void]

VERY interesting. India and the Dekkan traps were not antipodal to the Chicxulub strike.

This is why Luis and Walter Alvarez ruled out a connection between the impact and the basaltic flow.

Could the combination of trajectory and earth's rotation dropped enough crap on the Indian Continent to cause multiple fractures for the magma to start weeping out?

[Al Simmons]

Not a scientist, but believe Deccan traps dated about 300,000 years before Chixculub impact...

[Al Simmons]

Basically, any critter small enough to hide in a burrow (mammals, birds) or to hibernate through the catastrophe (snakes, crocs, lizards, amphibians) survived the initial firestorms and subsequent 3-4 month global winter (and global cooling that followed, acid rain, etc.)

If you were big and warmblooded (dinosaurs) you had nowhere to hide and even if you somehow survived the initial fiery cataclysm would have frozen/starved to death.

If you were small and warmblooded (mammals) you survived the fire and freeze underground, undoubtedly feasting on the carrion littering the entire face of the earth. Ditto for small birds....

[Wiseghy]

Makes sense. I always thought that all the theories about complex reasons for Dino extinction ignored the basic simplicity of Occam's razor, i.e.; big meteor=dead Dino's. Why make it complicated?