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Re: Schwei[tz]er and Soft Tissue Recovery



 At the SVP meeting, there was an interesting investigation on the
 metagenomics of dinosaur soft tissue preservation. The gist of it
 was that the material recovered from Mesozoic fossil bone had gene &
 protein material that matched WAY too many living things, and
 matched them WAY too perfectly.

Wait. What? There's DNA in it??? That _has_ to be contamination. Protein is one thing, iron-crosslinked protein yet another, but DNA, even in tiny fragments, doesn't last longer than 100,000 years -- unless it's frozen, which it's not, or maybe unless it stays completely dry throughout, which isn't possible in a well-drained sandstone. Did they really say there's DNA in it? I didn't notice that on their poster.

 One thing to be 'turkey-like' (and therefore distantly related to
 birds), another to be a plain old turkey. The authors at the talk
 supposed that genetic and protein material had leached through the
 soils, and invaded the fossil bones (Researchers in the tropics, as
 far as I understand it, do (somewhat similar) environmental DNA
 sampling to ID the different genetic types of things that are out in
 the forest (w/o having to ID the living animal). That's a pretty
 fascinating discovery in and of itself. They also felt that bacteria
 could make (and indeed showed similar) tubular structures that look
 like blood vessels.

 Later I noticed a poster from (if I recall correctly) someone in Dr.
 Schweitzer's group identifying the material in the soft tissue as
 definitely collagen.

...without sulfur in it. They proposed, on the poster, that it could have been lost by an unknown diagenetic process. :-/

The material they sequenced may all have been contamination. Yes, even the one identical to ostrich collagen; contamination in a lab is easy, and the methods are sensitive enough to detect tiny amounts.

 So what does anyone think about this, seems like the issue is still
 open, and this material was recovered quite a while ago.

 Has there been any sectioning of the 'goop' that Dr. Schweizter
 found, for histological examination (beyond what she's already done)?
 Does it react with biological stains that can distinguish between
 material like collagen and bacterial films?

Oh yes. Schweitzer et al. did try antibodies against collagen, and they do react with the samples. The question is whether the collagen is contamination.

 If genes and proteins from the environment are leaching into the
 fossil, should'nt they also be in the surrounding rock, indeed, might
 it be possible to detect higher concentrations closer to the surface
 and outside the bones? Coring at the site might be informative in
 that respect.

I don't think that has been done yet.