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Re: K-Pg extinction global firestorms



I think it is a bit premature for us to say that anything is ruled out at
this point.

I have not read the Robertson et al. paper, so take my opinion with that
in mind.

But the idea that "all surviving species were plausibly able to take
shelter from heat and fire underground or in water" is not obviously
supported. Crown group birds had diversified by the K-T, and there is no
evidence that ratites, volant paleognaths, and galliform birds, had any
such sheltering opportunities. These groups do not build burrows that they
normally shelter in, and they were not divers.

Moreover, the impact on plant communities seems to have been worst at the
closest proximity to the impact site (North America), and far less severe
at great distance (New Zealand). In the latter case there were,
apparently, NO plant extinctions at the K-T boundary. If the Robertson et
al. model truly predicts a uniform global firestorm, then the model seems
contradicted by the fossil evidence of the southern hemisphere.

Jason Brougham
Senior Principal Preparator
American Museum of Natural History
jaseb@amnh.org
(212) 496 3544





On 3/29/13 10:56 AM, "Richard W. Travsky" <rtravsky@uwyo.edu> wrote:

>
>
>On Wed, 27 Mar 2013, Ben Creisler wrote:
>>
>> A new paper of interest:
>>
>> Douglas S. Robertson, William M. Lewis, Peter M. Sheehan & Owen B. Toon
>>(2013)
>> K-Pg extinction: Reevaluation of the heat-fire hypothesis.
>> Journal of Geophysical Research: Biogeosciences (advance online
>>publication)
>> DOI: 10.1002/jgrg.20018
>> http://onlinelibrary.wiley.com/doi/10.1002/jgrg.20018/abstract
>
>So, what about the other recent news that it could have been a comet?
>That 
>has a different composition from, say, an asteroid. It would seem to rule
>out a comet.