RE: Sinosauropteryx filament melanosomes challenged

[Jaime Headden <qi_leong@hotmail.com>]

  When eventualloy I get back to my blog, this is what I will write:

  TLS has, once again, failed to reproduce his results while investigating 
ostensibly avian fossils in the same (Jiufotang) formation from whence 
*Sinosauropteryx* derives. This is important because the finding of 
color-banding was first proposed for avian or 
"more-avian-than-*Sinosauropteryx*" feathers before it was projected onto 
*Sinosauropteryx*. If TLS were to have made this comparison, which he has so 
far failed to do for several years in his critical studies, I might have 
reasons to support this work on its face. But yet again he compares it only 
with dessication of dermis structures for extant animals, and not comparison to 
fossil material that is (arguably?) avian in TLS's eyes. The throwing of the 
word "merit" around in the paper just _rankles_.

Cheers,

Jaime A. Headden
The Bite Stuff (site v2)
http://qilong.wordpress.com/

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


"Ever since man first left his cave and met a stranger with a
different language and a new way of looking at things, the human race
has had a dream: to kill him, so we don't have to learn his language or
his new way of looking at things." --- Zapp Brannigan (Beast With a Billion 
Backs)





----------------------------------------
> Date: Sat, 4 Dec 2010 22:33:46 +0000
> From: bh480@scn.org
> 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/
>