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Re: Sinosauropteryx filament melanosomes challenged



I did not read the paper yet, but from the abstract, it appears as
reasonably skeptical, and provides alternative explanations from
decomposition experiments. If this can help in testing our assumptions
(I do not say this to support Bandits, of course), to me this kind of
contributions should be welcome, whatever the allegiances of
Lingham-Soliar.

2010/12/5 John Hunt <john.bass@ntlworld.com>:
> No surprise there.  It amazes me how quickly bandits can knock out papers.
>
> -----Original Message-----
> From: bh480@scn.org [mailto:bh480@scn.org]
> Sent: 04 December 2010 22:34
> To: dinosaur@usc.edu
> Subject: Sinosauropteryx filament melanosomes challenged
>
> From: Ben Creisler
> bh480@scn.org
>
> Another new paper. Pdf is free.
>
> Theagarten Lingham-Soliar (2010)
> The evolution of the feather: Sinosauropteryx, a
> colourful tail.
> Journal of Ornithology
> DOI: 10.1007/s10336-010-0620-y  (advance online
> publication)  (Online First™)
>
>
> A recent development in the identification of feathers in
> fossils by means of melanosomes was used to suggest that
> structures observed in an SEM of a filament in the basal
> theropod dinosaur, Sinosauropteryx, were phaeomelanosomes
> and that they represented conclusive evidence that the
> filaments were early feathers. At the most basic level,
> the claims of phaeomelanosomes are shown here to be
> founded on an optical illusion created when the SEM is
> reproduced at low image size—viewed at larger image size
> (~2× original) the structures are nondescript in both
> size and shape and impossible to equate with
> phaeomelanosomes. At a higher level of investigation, the
> study is seriously questioned for ignoring standard
> scientific protocol: despite size and shape being
> critical to the identification of the phaeomelanosomes,
> no statistically viable measurements of the structures
> (particles) were made—the measurements, which are simply
> conjectured, are shown here to be incorrect in the
> speculated sizes, and in shapes; inferences made on vital
> characters from birds and advanced non-avian dinosaurs,
> e.g. with respect to colour banding, are without
> confirmation in the test animal but conjectured on
> circular argumentation; alternative arguments, e.g. that
> the particles might be bacteria or colour from the
> overlying skin, are peremptorily dismissed or not
> considered; suggestions that the particles are embedded
> within the filament are without support since there is no
> evidence of cross-sections or tangential sections either
> made or occurring serendipitously—only a single section
> is reported, apparently of the filament’s surface. False
> dichotomies such as, if the structures are not bacteria
> they must be melanosomes, are questioned given that one
> of the most important factors in the taphonomy of ancient
> (structures in question, ~130 MYR) fossilised filaments
> i.e., decomposition—that the structures might reasonably
> represent the degraded remains of the filaments—is not
> even considered. Here, from experiments on the
> decomposition of native collagen in fish and reptilian
> dermis, SEMs of their ultrastructure show that
> distinctive spherical, elliptical or oblate particles,
> even more so than those figured in Sinosauropteryx,
> typically form during degradation. This is confirmed in
> SEMs of degraded collagen fibres in a 225-MYR ichthyosaur
> fossil, virtually point by point. In addition numerous
> small bead-like structures in the filament of
> Sinosauropteryx bear a striking resemblance to the unique
> 67-nm D-bands of collagen, in both shape and size. This
> paper does not question the value of scientifically
> meritorious identifications of melanosomes, as indeed of
> collagen and keratin, in interpreting the integumental
> structures of fossil animals. However, allegations of
> phaeomelanosomes in Sinosauropteryx are shown to be
> without scientific merit.
>
> http://www.springerlink.com/content/4555m8h3x6035653/
>
>
>