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Study Provides Compelling Evidence of Single Impact Extinction Theory 382

Posted by ScuttleMonkey
from the scientists-all-looking-for-someone-named-ele dept.
ectotherm writes to tell us that a new study at the University of Missouri-Columbia claims to provide compelling evidence that a single meteor impact was the cause of animal extinction 65 million years ago. From the article: "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."
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Study Provides Compelling Evidence of Single Impact Extinction Theory

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  • Re:Okay... (Score:3, Informative)

    by inKubus (199753) on Wednesday November 29, 2006 @05:53PM (#17040474) Homepage Journal
    Some scientists believe that there were multiple events that caused the massive global change that caused the mass extinction. This theory is that there was only one.

    It's amazing to imagine the world populated by giant birds and lizards. But what did these creatures breathe? Perhaps the world was covered in plant life, which provided a lot of Oxygen. Then the impact hit, killing the plants, lowering the oxygen enough that the larger animals just sort of suffocated. The smaller animals had smaller lungs, less air requirements, and thus did not perish.

  • by cdrguru (88047) on Wednesday November 29, 2006 @08:01PM (#17042216) Homepage
    Uhhh, no.

    Crater impacts in millions of years:

    Yucatan - 65,000,000

    Nordlingen, Germany - 5,000,000

    Barringer, Arizona - 0.05

    Yeah, there are a bunch of others out there but the spread is a lot more than you seem to think.
  • Self-aligned dates (Score:2, Informative)

    by 2901 (676028) on Wednesday November 29, 2006 @08:12PM (#17042326) Homepage Journal

    The interest in the article is that they have found a single sediment with both the K-T boundary marked by loss of marine plankton species and debris from the impact at the same level. So they can look at date difference without needing absolute dates and without the errors possible in isotopic geochemistry.

  • by flyingsquid (813711) on Wednesday November 29, 2006 @09:13PM (#17043052)
    The problem with all these sedimentological studies is that the statistical period between large meteorite impacts and the systematic error in the dating of the sediments (using isotopic geochemistry) in addition to the ambiguity in the fossil record (and the dating errors in those sediments) means that it's guaranteed that you will find a correlation between any mass extinction and a large meteorite impact event.


    This is really misleading- there may be other craters out there, but there is certainly nothing else out there like Chicxulub. The Chicxulub crater is one of the largest meteorite craters ever discovered; vastly larger than anything we've ever seen in human history or anything that's happened in the past 65 million years. The rock or comet responsible for it is thought to have been about 10km in diameter, travelling at tens of thousands of miles per hour; in terms of energy released by that blast, we're talking about something that would have made a full-scale nuclear exchange between the US and USSR look like a couple of kids playing with fireworks. It is estimated that a Chicxulub-scale impact occurs on the order of once every 100 million years, if that often.

    The end-Cretaceous mass extinction, meanwhile is one of the five largest mass extinctions to occur in the past half-billion years. In other words, a 1-in-100 million year event. What are the odds of two such large scale, exceptionally rare events occurring simultaneously? Pretty much nil. True, there may be a few scientists out there who debate whether the K-T extinction was caused by the Chicxulub, and they try to poke holes in the Alvarez extinction hypothesis. But they haven't been able to present a compelling alternative to it.

    Finally, ammonites go right up to the K-T boundary. In a paper in PNAS, Pope et al. show stratigraphic ranges of ammonites; the majority of ammonites extend to within a few tens of thousands of years of the K-T boundary and many go extinct right at the boundary.

  • by pedantic bore (740196) on Wednesday November 29, 2006 @09:23PM (#17043168)
    Go back and read it again. Afterward, God promised he'd never do it again. After nuking a few cities of the plain, and drowning almost everything else, he realized it was time to chill out and limit himself to a few massacres here and there.

    p.s., yes, I'm probably going to hell for that.

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