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Re: Double impact at K-T boundary ?



So then.....
The Dinos would have had to make it through THREE?! impact events if they were 
to make it to the present?
Well, the Avian lineage managed, too bad about the rest.

http://news.nationalgeographic.com/news/2009/10/091016-asteroid-impact-india-dinosaurs.html



--- On Fri, 8/27/10, Gautam Majumdar <gmajumdar@freeuk.com> wrote:

> From: Gautam Majumdar <gmajumdar@freeuk.com>
> Subject: Double impact at K-T boundary ?
> To: dinosaur@usc.edu
> Date: Friday, August 27, 2010, 1:55 PM
> Geology 2010; 38:
> 835-38    doi: 10.1130/G31034.1 
> 
> Abstract
> 
> The end-Cretaceous mass extinction has been attributed by
> most to a single 
> asteroid impact at Chicxulub on the Yucatán Peninsula,
> Mexico. The discovery 
> of a second smaller crater with a similar age at Boltysh in
> the Ukraine has 
> raised the possibility that a shower of asteroids or comets
> impacted Earth 
> close to the Cretaceous-Paleogene (K-Pg) boundary. Here we
> present 
> palynological and delta-13C evidence from crater-fill
> sediments in the . Our 
> analyses demonstrate that a post-impact flora, formed on
> the ejecta layer, was 
> in turn devastated by the K-Pg event. The sequence of
> floral recovery from the 
> K-Pg event is directly comparable with that in middle North
> America. We 
> conclude that the Boltysh crater predated Chicxulub by ~
> 2-5 k.y., a time 
> scale that constrains the likely origin of the bodies that
> formed the two 
> known K-Pg craters.
> 
> Interestingly a double impact was proposed by Wolfe in
> 1991
> 
> Palaeobotanical evidence for June 'impact winter' at the
> Cretaceous/Tertiary 
> boundary, Nature 1991; 352: 420-2 
> 
> --
> Gautam
> 
>