Re: Is there a feathered juvenile *Psittacosaurus* specimen?

["Jaime A. Headden" <qilongia@yahoo.com>]

David Marjanovic (david.marjanovic@gmx.at) wrote:

<Today morning I received, for reasons I don't quite understand at the moment,>

  Perhaps a response to earlier comments on the issue?

<In fig. 11C I see the striations that are called "integumental structures
[...] the striations seem to have a rather random orientation. They are not
bundled into branching structures. Many are parallel over some 2 cm.>

  This is actually possibly what the study on random fibers in collagen bundles
would be preserved as, not regular pennate-like structures that would immitate
feathers, which is nice when it happens once, randomly, in a small area, but
not regularly, over the entire fossil, in shapes mimicking feathers, and in so
many fossils including matching the same structures in birds, that to call them
collagen fibers rather than feathers is stretching things. But it's nice in
this paper to 1) see how randomnality is expressed in collagen by using
matchsticks, and 2) that there are Jehol biota fossils which show this random
collagen system. However, it makes sense that these are heavy collagen systems,
prone to preservation, and since bone surfaces rarely seem covered in ANY
integumental features in Jehol-biota fossils, excluding them as surface
integument (i.e., skin) is presumptuous, as well as attributing them below the
ribs, when it is also possible they were parts of the intercostal tissues, thus
neither above nor below the ribs. This specimen is nice to document the issue,
but it's not "news", as specimens by the dozens, including *Monjurosuchus* and
*Keichousaurus* specimens are also known by such specimens, *Jeholotriton,* and
various other vertebrates. *Sinosauropteryx* is perhaps the most fascinating of
these for it's implications as a first bird, as well as setting the bar very
early for coelurosaur body tissues, whichg expand well beyond the expected body
wall. In discussing the last issue of _JVP_, I mentioned a paper on a new
specimen of *Dialingosaurus* which shows beautiful preservation of squamation
without these "hair bundles" all over it Martin has (elsewhere) expected to
prove his case. Indeed, I mentioned some time back that Jehol salamanders show
such "hairy" structures only around their gill arches, a feature one expects in
neotenic salamanders; but smoother, much less "complex" surface patterns of the
body outline elsewhere on the fossils. And there are perhaps a dozen such
salamander fossils to corroborate this. They do not themselves look like hairy,
feathered dinobirds, and implies the hairy look found in birds and dinosaurs
from the Jehol sediments are unique to them. (For whatever reason.)

  Which leads me to my own major criticism of the paper David mentions (which I
never got around to posting here):

  The authors NEVER took a bird fossil, say *Confuciusornis*, and applied their
technique, used to ascertain random collagen bundles in ichthyosaur skin, thus
allowing them to TEST their predictive power by excluding those features the
authors are _confident_ are found in birds. If so, the entire paper may have
been irrelevant, since the only new piece of data to the paper was
Theagarten-Soliar's work, otherwise it's a review of previous work Feduccia has
published. In addition, the authors argue against the filamentous nature of the
structures in *Sinornithosaurus* (Dave, NGMC 91) but later stress they are bird
allies but not theropods, so if they were feathers, _that's okay_. No,
actually, it's not, because if they ARE feathers, you see, their entire use of
random structures to identify feathering collagen patterns, as they attempted
using a dehydrated and perturbed hydrophid skin way back when, then the
branching structures really ARE feathers, and the paper was a waste of time.
Thus the only good part was the application of the collagen perspective in real
fossils other than ichthyosaurs, and it seems to in the end to put the nails
into the coffin of the idea of dinosaurs surrounded by collagenous blubbery
skins.

  Now, just imagine, if they are right, if the outlines of the *Monjurosuchus*,
*Jeholotriton*, and various dinosaurs, as well as ichthyosaurs, are collagen
imprints of natural body outlines, they would have been some massively blubbery
skins, and skins so thick the salamanders would have suffocated and dehydrated
to death for lack of the ability to aspire and absorb moisture through the
dermis. Ah, c'est la vie.

<On to the last new claim about a fossil. Illustrating an apparently
unpublished specimen of *Pelecanimimus*,>

  That's actually the holotype of *Pelecanimimus polyodon*, LH 7777.

  Cheers,

Jaime A. Headden

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

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