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RE: Bird reduce their "heating bills" in cold climates
--- On Tue, 7/6/10, Jaime Headden <firstname.lastname@example.org> wrote:
> From: Jaime Headden <email@example.com>
> Subject: RE: Bird reduce their "heating bills" in cold climates
> To: "Jason" <firstname.lastname@example.org>, "Dinosaur Mailing List"
> Date: Tuesday, July 6, 2010, 4:18 AM
> Jura wrote:
> <Then there is the work of Zhou and Niswander (1996),
> and Sawyer & Knapp (2003) that show an antagonistic
> relationship between scales and feathers, with the scales on
> birds legs being a re-acquisition of the trait (by actively
> suppressing feather development) rather than being a hold
> over. This has further been supported by the discoveries of
> _Microraptor_, _Anchiornis_, _Pedopenna_ and a reassessment
> of the legs of _Archaeopteryx_ and _Confusciornis_ all of
> which showed feathers extending down to the feet, and
> suggesting that a "feathers all over" situation was the
> plesiomorphic condition. That birds have scales on their
> tarsal metatarsal region fits well with work by Alibardi
> & Thompson, showing that the scale formation on the this
> region of the foot occurs in a separate wave from that which
> covers the body.>
> While the antagonistic relationship between feathers and
> scales in birds may be apparent in a localized sense, there
> is no data in those works that supports a body-wide all or
> nothing hypothesis. This is especially true in birds where
> the two types of integument exist side-by-side on a single
> animal. When you raise the examples where feathers are
> present in various fossil maniraptorans, you ignore the
> presence of contradicting evidence that has been raised in
> the past on this exact topic:
I do nothing of the sort. That some maniraptorans (notably "Dave") preserve
scales on the tarsometatarsal region, just shows that by that time, scales had
re-evolved in that lineage. It's not like you were seeing a scaly face, and
tail too, or scales intermingled with feathers on the body.
As for _Archaeopter
it and _Confusciornis_ found feathers extending down the legs (and apparently
a four winged thing too).
> 3. Descriptive anatomy of the filamentous or
> "quill"-like structures in some dinosaurs in which
> squamation is present (see Lingham-Soliar on
> *Psittacosaurus*) show that this material is intersperses
> and omnipresent, regardless of the position of the
> structures. Naysaying that the structures are "possibly also
> plants" is a hand-wave: You must somehow account for the
> potential that they are what they are claimed to be in your
> hypothesis to test said hypothesis. This works when we have
> isolated elements as in *Longisquama insignis,* where there
> is only one skeleton associated with the structures, and
> several specimens of structures but no skeletons. No other
> associative hypothesis has been forwarded to account for
> Jiufotang "quills" that are not integumental (yet), nor to
> account for their apparent hollow form, which is backed up
> by similar structures (in the same skeletal region) in
> *Tianyulong confuciusi*.
Yeah, "apparent" is the operative word there. Zheng et al state that the
structures are hollow based of apparent translucency, but unfortunately they do
not provide any pictures to aid that statement, as all the _Tianyulong_
pictures show them to look like 2D scrapings.
As for the "quills" that they have been questioned as being plant matter is
touched on by the authors in the (currently only) paper, to which their
response was apparently "we don't think it's plant matter."
That the fossil's collection technique has made everyone leery of messing with
it, doesn't help matters either.
As for the association of both together, I already touched on it. The
association probably means that -- if truly integumentary -- then is more
likely a scale derivative more akin to the "spines" on some sauropods, than the
feathers in maniraptors.
hesis of competitive
> expression between scales and feathers in the legs of some
> birds it applicable, it appears this is not substantive to
> account for the material which shows filamentous versus
> squamous integument in OTHER parts of the body, such as the
> face, or the tail (see, for example, *Scansoriopteryx
> heilmanni*/*Epidendrosaurus ningchengensis*, where a patch
> of scales is preserved as a mould in the tail, while the
> limbs and anterior chest present traces of filamentous
The alleged scaly tail of _Scansoriopteryx_ / _Epidendrosaurus_ has been
considered suspect since it was first described. Czerkas & Chongxi point out
that the scales show evidence of post mortem removal, and more likely came from
the tarsometatarsal region.
> 5. Even more interesting, like some maniraptorans,
> *Tianyulong confuciusi* possesses multiple kinds of
> filamentous integument, including flattened fibers, small
> hollow tubes, and basally bound, branching bundles [hah!] of
> filaments (as is found in NGMC 91).
Multiple kinds of integument? Based on what study?