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RE: Wrong Reconstructions
I must confess my earlier mistake in the thread, that of concusing barbed
feathers with barbed-and-barbuled feathers, using the term plumulaceous to
exclude the feathers of *Scansoriopteryx* when, perhaps, they should have
persisted: the term pennaceous would have been more appropriate, or at least to
describe the form of the feather as a whole, due to the presence of barbules in
a pennaceous feather, but their lack in a plumulaceous feather (which would
describe those of *Scansoriopteryx*).
I also admit that Mike is correct; as Jason also argued, that preservation
may exclude clarity in preserving fine details like barbules. Certainly, the
neat form of the vanes and their "wholeness" implies the presence of barbules,
making them pennaceous; this occurs in *Microraptor gui*, but it seems
problematic in preservation of *Sinornithosaurus milennii* OR NGMC 91 -- and is
also the case in *Scansoriopteryx heilmanni*. I would contend however, that the
irregular and "messy" preservation of feathers apparent in some taxa may be
consistent with their form of feather, rather than be an artefact of
preservation, as was contended for *Microraptor gui*: Barbules are inferred,
rather than observed, due to feather form (or were, at any rate -- Hone et al.
2010 contend that details of feathers remain difficult, while their form is
still consistent with the above argument).
Hone, D. W. E., Tischlinger, H., Xu X. & Zhang F.-c. 2010. The Extent of the
preserved feathers on the four-winged dinosaur *Microraptor gui* under
ultraviolet light. PLoS ONE 5(2):e9223. doi:10.1371/journal.pone.0009223
Excuse my confusion.
Jaime A. Headden
The Bite Stuff (site v2)
"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
> From: MHabib@Chatham.edu
> To: email@example.com
> CC: firstname.lastname@example.org; email@example.com
> Date: Tue, 25 Jan 2011 17:19:00 -0500
> Subject: Re: Wrong Reconstructions
> On Jan 25, 2011, at 4:34 PM, Jaime Headden wrote:
> > The real issue is that aside from the "ebff"s, "feathers" in all fossils
> > are non-plumulaceous, lacking apparent barbs, and nothing similar to
> > "feathers" in the conventional (modern) sense.
> This does seem to be the case for the most part, but I've been wondering
> recently about how literally we can take this observation. My general
> question (and I'm keen to see what others here think) is this: given an
> animal *with* modern-grade, plumulaceous feathers, what are the chances that
> it would preserve with that feather structure clearly apparent? Might we just
> be seeing minor traces of much heavier feathering in many species?
> - The first dromeosaurids discovered with feather impressions seemed to show
> relatively non-barbous feather structures, but subsequent finds of quill
> knobs in Velociraptor and the feathering in Microraptorines might suggest
> that more "modern" grade feathers were present in a wider range of taxa, and
> just don't always show up clearly.
> - In some specimens a range of feather types is preserved, which provides
> confidence that those apparently lacking barbs were indeed downy in that
> individual. However, often the feather impressions are somewhat uniform,
> possibly suggesting that we are only seeing trace elements of feather
> structure. There are Confuciusornis specimens that look merely "fuzzy"
> (pardon my intense use of technical jargon there...), for example - we know
> from other specimens that, in fact, this taxon possessed contour feathers.
> One wonders how often this happens, given that most taxa are not represented
> by hundreds of specimens in the manner of Confuciusornis.
> Just food for thought.
> Michael Habib
> Assistant Professor of Biology
> Chatham University
> Woodland Road, Pittsburgh PA 15232
> Buhl Hall, Room 226A
> (443) 280-0181