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Re: Dinosaur heart found?




On Fri, 21 Apr 2000 NJPharris@aol.com wrote:

> In a message dated 4/21/00 1:35:26 PM Pacific Daylight Time, 
> dinoland@mailcity.com writes:
> 
> > And, yeah, Dr. Brochu in the Fox News report questioned why only the heart 
> > would be preserved.  Russell or one of the other authors mentioned 
> something 
> > about bacteria, but why would this bacteria only target the heart?  
> 
> Well, Russell was asked this question during his National Public Radio 
> appearance, and he answered that he did not know why the heart specifically 
> was preserved, except that it is composed of very dense muscle, as opposed to 
> the other viscera, which tend to be rather soft and spongy.


Russell also expressed puzzlement as to why the trachea was not preserved. 
The trachea is composed of rather dense tissue surrounded by rings of
even denser cartilage to strenthen the airway (prevent its collapse).  If
cartilage around the uncinate processes was mineralized, then why weren't
the tracheal rings similarly mineralized? 

By the way (for any lurking geologists/mineralogists on the list), Russell
noted in passing that much (all?) of the preserving medium for the heart
seems to be the hydrated iron oxide mineral "goethite".

And I'll add a bit of trivia as well.  The "ironstone"-cemented fossils
from the Hell Creek Fm. are almost always cemented by one or more of the
following minerals: siderite (an iron carbonate mineral), "limonite" (a
mix of goethite/hematite), goethite, and (rarely) hematite alone.

In increasing order of difficulty to prepare, siderite and goethite tend
to be the easiest to remove, and "limonite"- and hematite-cemented matrix
tends to be the worst to remove.

            <pb>