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New "Last Dinosaur" Find Backs Asteroid Extinction

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  • No, it doesn't (Score:5, Informative)

    by Wyatt Earp (1029) on Wednesday July 13, 2011 @03:45PM (#36754076)

    The margin of error on when the last dinosaurs were existent and the margin of error on when the K-T boundary was deposited are both hundreds of thousands of years.

    In some places there are at least 300,000 years of sediment between the fossil evidence of the Cretaceous–Tertiary extinction event and the K-T boundary.

    K-T boundary has is dated to (65.5 ± 0.3) Ma, the Cretaceous–Tertiary extinction event is dated to 65.5 Ma, so the impact could have been the day the last dinosaurs were alive, it could have been 300,000 years before, 11 years after, or 213,417 years after.

  • by Paltin (983254) on Wednesday July 13, 2011 @04:25PM (#36754706)
    That's not how it works.

    Considering the vast amount of time captured in even 13 cm of strata, there are many more generations of dinosaur corpses created and sorted through the taphonomic filter than would be created by a sudden extinction event. The deposition associated with the Hell Creek is one of rivers - which means there's a lot of energy to destroy things, as well as problems transporting from death location into the river to begin with. Simply put, there is no reason to expect that you'd fine a single bone from the last generation of dinosaurs - and even if you did, you'd have a hell of a time proving it.

    Here's an example paper from the modern that looks at this problem : http://www.cornellcollege.edu/geology/greenstein/personal/Reprints/Diadema.pdf [cornellcollege.edu]

    Clear record of mass mortality, like you expect, requires exceptional preservation such as that captured in the Burgess Shale. That isn't the case for the Diadema, or for the Hell Creek formation.

    And yes, of course you can associate things at 13cm. The number of vast changes in flora and fauna at the K/T boundary match up as well as could be expected with the Iridium spike and other impact markers. This is strong evidence that there is an association.

Your own mileage may vary.

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