Re: secondary flightlessness (wordy)

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

Ron Orenstein wrote:

<An odd thought I had while looking at Caudipteryx (or pictures of it,
anyway) - a number of birds (eg grouse, cranes) use wing-assisted
upward leaps of the type Tom is talking about as part of their
displays.  I think it is reasonable to assume Caudipteryx used that
remarkable tail fan in some sort of display.  I wonder if it is fair
to speculate that the arm-feathers may have assisted display by
allowing airborne, flap-assisted leaps - or to jump even further and
note that if so, display might have been a driving factor in the
evolution of powered flight (a mechanism I have not seen anyone
suggest for the "ground-up" hypothesis).  Of course none of this can
be proved.......>

  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.

  But it doesn't rule out *Protarchaeopteryx*, though.

  Jaime A. Headden
_________________________________________________________
DO YOU YAHOO!?
Get your free @yahoo.com address at http://mail.yahoo.com