_Caudipteryx_ feathers (was secondary flightlessness)

["Ralph Miller III" <gbabcock@best.com>]

Jaime A. Headden <qilongia@yahoo.com> wrote:
>   The primary feathers of *Caudipteryx* show a flexible rachis, and in
> at least the first three preserved primaries on the specimen
> photographed in _Nature_ and _national Geographic_ there is an extreme
> double flex that would, I think, demonstrate a very unaerodynamic
> ability to catch wind or aid air pressure as would be required by
> sustained airlift in a jumping dinobird like this fellow. These
> primaries are, actually, very similar to the arm feathers of the emu
> (*Dromaius*) which are tapered down to a point (at least for those
> first primaries) and are symmetrically "vaned". The barbs of the
> feathers do not seem to interlock, so this is a minus for
> *Caudipterys* being a sustained-leaper.

Regarding the pronounced double flexion of the remiges you observe in the
_Caudipteryx_ specimen, is it possible that this flexion you see occurred
after death?  Could not the rachises have been subjected to unusual traumas
postmortem?  

Regarding interlocking barbs, at the National Geographic Society press
conference on Tuesday, June 23, 1998, Dr. Philip J. Currie said of the
_Caudipteryx_ feathers that "barbules must have been present" to hold the
barbs parallel (as they appear in the specimens).  The rachises of adjacent
remiges likewise appear to have been preserved parallel to one another in
the photographs, as well as in the accompanying illustrations.  Given the
lack of resolution in the fossil feathers (in so far as the photographs
reveal them), I fail to see the basis for applying emu feathers as an
appropriate analog to the preserved feathers of _Caudipteryx_.  These
structures apparently did not fossilize with the microscopic fidelity of
the _Archaeopteryx_ feathers.  The rectrices are held parallel to one
another, and there are no obvious gaps between adjacent feathers. 
Particularly if you accept Dr. Currie's determination that the feathers had
barbules, what leads you to conclude that the feathers did not interlock?  
    

Kevin Padian's commentary in today's _Nature_, _When is a bird not a
bird?_, also addresses your concerns.  I quote:

"_Caudipteryx_ and _Protarchaeopteryx_ go it (referring to
_Sinosauropteryx_) one better, evolving long feathers with a central rachis
(shaft).  Were these feathers airworthy?  Their vanes are symmetrical and
very even, suggesting interlocking barbs, although most flying birds have
asymmetrical feathers.  However, the arms of _Caudipteryx_ are only 60% as
long as the legs, and they are only two-thirds as long as in
_Protarchaeopteryx_ (in Archaeopteryx_ they are of more or less equal
length).  Evidently, the arms and feathers were not large enough for flight
(the plumage is not known well enough to say if it was effective as
insulation, or what other functions it may have served).  The feathers of
_Archaeopteryx_ seem to be a natural extension of this trend, so to speak,
but they are not much different qualitatively.  So the available evidence
suggests that structurally airworthy feathers may have evolved before they
were long enough, or their possessors able to use them, for flight."      

Do you disagree with the above statements?

On another note, the caption for figure 8b from the _Nature_ paper, which
refers to "Feathers of _Caudipteryx zoui_" reads: "Rectrices, showing color
banding..."  Color banding preserved in fossil dinosaur tail feathers? 
Very interesting.   

-- Ralph Miller III     gbabcock@best.com

Qu.: How do you get down off a dinosaur?