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Re: Sinosauropteryx filament melanosomes challenged

It is also worth noting that Lingham Soliar's paper was accepted in July and 
revised October 11, but it does not refer to Plumage Color Patterns of an 
Extinct Dinosaur, Li et al., Science vol 327 12 March 2010. Lingham Soliar's 
criticisms of the methods of Zhang et al. may be valid and even constructive, 
but  the Li et al. paper explicitly seeks to improve on the methods of Zhang et 
al.  by using large statistical samples, sharp high - resolution figures, and 
analyses of melanosome size, shape, density, and distribution. They find that 
the feathers of Anchiornis do, indeed, preserve melanosomes.

Of course, Lingham - Soliar could respond that Anchiornis is actually a bird. 
But then we might wonder why none of the hundreds of specimens of 
archosauromorphs like Hyphalosaurus and Monjurosuchus, lizards like 
Dalinghesaurus, and turtles like Manchurochelys, show filamentous tufts like 
Sinosauropteryx. If collagen in diapsid skin can fossilize in a  way that looks 
like keratin filaments, then why does this never happen in archosauroforms 
below the theropoda?

On Dec 4, 2010, at 5:33 PM, bh480@scn.org wrote:

> 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 FirstË)
> 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 sizeËviewed at larger image size 
> (~2â 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 madeËthe 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 serendipitouslyËonly a single section 
> is reported, apparently of the filamentâs 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., decompositionËthat the structures might reasonably 
> represent the degraded remains of the filamentsËis 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/

Jason Brougham
Senior Principal Preparator
American Museum of Natural History
(212) 496 3544