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Re: Study Finds that a Single Impact Killed the Dinosaurs



Palaeosols of the uppermost 2-3 meters of the Hell
Creek fm. are more acidic than those from lower
sections.  The only common fossils from this level are
found in stream deposits, where the water acted as an
acid buffer.  For more information on this topic, see
the reference below:

Retallack, G. J., G.D. Leahy, and M.D. Spoon. 1987.
Evidence from paleosols for ecosystem changes across
the Cretaceous-Tertiary boundary in Montana. Geology
15: 1090-1093.

Guy Leahy

--- dinoboygraphics@aol.com wrote:

> >>>But there is an overall lack of terrestrial
> fossils in the uppermost
> Hell Creek fm. Stuff really thins out ~20 m below
> the Hell Creek/Fort
> Union contact in eastern MT and in many places is
> almost non existant,
> so something other than an impact must have been
> happening to the
> environment. <<<
> 
> Or else the geochemistry was changed by the impact
> itself (e.g. acid 
> rain) resulting in a reduction in the liklihood of
> preservation as you 
> get closer to the K/T boundary.  Not saying it's
> right, but you have to 
> control for confounding factors before it's positive
> evidence.  How 
> about the percentage of teeth vs. other bones near
> the boundary? 
> Perhaps differences in the preservation of types of
> apatite would be a 
> test of whether it was truly faunal reduction or a
> change in 
> preservational regime.
> 
> Scott Hartman
> Science Director
> Wyoming Dinosaur Center
> 110 Carter Ranch Rd.
> Thermopolis, WY 82443
> (800) 455-3466 ext. 230
> Cell: (307) 921-8333
> 
> www.skeletaldrawing.com
> 
> -----Original Message-----
> From: lhall@montana.edu
> To: koreke77@yahoo.de
> Cc: dinosaur@usc.edu
> Sent: Wed, 29 Nov 2006 9:11 AM
> Subject: Re: Study Finds that a Single Impact Killed
> the Dinosaurs
> 
> But there is an overall lack of terrestrial fossils
> in the uppermost 
> Hell Creek fm. Stuff really thins out ~20 m below
> the Hell Creek/Fort 
> Union contact in eastern MT and in many places is
> almost non existant, 
> so something other than an impact must have been
> happening to the 
> environment. 
>  
> On 11/29/06, evelyn sobielski <koreke77@yahoo.de>
> wrote: 
> > But wasn't the multiple-impact theory as of
> recently 
> > more about the Chixculub bolide breaking up on
> entry 
> > and thus multiple, but essentially *simultaneous* 
> > impacts? Analysis of the bolide's trajectory
> could 
> > help. 
> > 
> > Eike 
> > 
> > 
> > 
> >
>
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> 
> 
>
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