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Re: [dinosaur] Difficulties in discriminating dinosaur peptide sequences from modern cross-contamination (free pdf)



On 05/31/2017 03:42 AM, Ben Creisler wrote:
> A decade ago, reports that organic-rich soft tissue survived from
> dinosaur fossils were apparently supported by proteomics-derived
> sequence information of exceptionally well-preserved bone. This initial
> claim to the sequencing of endogenous collagen peptides from an
> approximately 68 Myr Tyrannosaurus rex fossil was highly controversial,
> largely on the grounds of potential contamination from either bacterial
> biofilms or from laboratory practice. In a subsequent study, collagen
> peptide sequences from an approximately 78 Myr Brachylophosaurus
> canadensis fossil were reported that have remained largely unchallenged.
> However, the endogeneity of these sequences relies heavily on a single
> peptide sequence, apparently unique to both dinosaurs. Given the
> potential for cross-contamination from modern bone analysed by the same
> team, here we extract collagen from bone samples of three individuals of
> ostrich, Struthio camelus. The resulting LC–MS/MS data were found to
> match all of the proposed sequences for both the original Tyrannosaurus
> and Brachylophosaurus studies. Regardless of the true nature of the
> dinosaur peptides, our finding highlights the difficulty of
> differentiating such sequences with confidence. Our results not only
> imply that cross-contamination cannot be ruled out, but that appropriate
> measures to test for endogeneity should be further evaluated.

I really dislike studies like this, not because of the result... but
because of the unsubstantiated accusation and application of the conclusion.

In the case of the T-Rex she could show you the protein material as it
was pulled out of the bone tissue?  Is the author accusing her here of
fraud based on would haves and could haves without any substantial or
direct evidence.

The real conclusion of this study is not that the studies were
contaminated with Kentucky fried chicken, but that Ostriches are related
to T-Rex and  Brachylophosaurus... something we pretty much know and
thank you for adding more evidence to that phenology.

> In a subsequent study, collagen
> peptide sequences from an approximately 78 Myr Brachylophosaurus
> canadensis fossil were reported that have remained largely
> unchallenged

This is a nasty left handed accusation that is substantially wrong and
this paper certainly doesn't provide any kind of challenge.  There is a
growing body of soft tissue evidence, both in the rock and with tissue
samples being examined in a variety of ways from scanning technology to
biochemistry.  If you want to show these two studies were flawed, then
show me the evidence, and not a hypothesis stated as a conclusion that
is not directly based on the studies technique, or your own direct
findings of said specimens.