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Re: Science feather strength debate



> The feathers closest to the armpit move the
> slowest and the least far during a flap, so do they even
> generate any lift?

Yes, they do, wings generate lift even when not moving at all in gliding flight.

Though I doubt the part of the wing closest to the body generates much thrust 
during a flap.

--- On Sun, 11/14/10, Jason Brougham <jaseb@amnh.org> wrote:

> From: Jason Brougham <jaseb@amnh.org>
> Subject: Re: Science feather strength debate
> To: augustoharo@gmail.com
> Cc: tijawi@gmail.com, dinosaur@usc.edu
> Date: Sunday, November 14, 2010, 7:58 PM
> 
> Yeah, also, what exactly is the aerodynamic function of
> tertials? A wing
> is not a sail or a parachute. The feathers closest to
> the armpit move the
> slowest and the least far during a flap, so do they even
> generate any
> lift?
> 
> 
> > Agreeing with your opinion, as far as I am aware, as
> the bird humerus
> > is surrounded by muscle in a greater measure than the
> ulna, it is to
> > be expected that the plumage is not so firmly attached
> to the skeleton
> > at this point, and it may thus be more easily
> disarticulated with
> > decay. Correct me if I am wrong, but I never read or
> saw first-hand
> > humeri with feather knobs, while they can be found in
> the
> > carpometacarpus in addition to the ulna. If true, the
> lack of these
> > feather attachment structures may suggest feathers
> were not attached
> > to the humerus.
> >
> > 2010/11/14 Tim Williams <tijawi@gmail.com>:
> >> David Marjanovic <david.marjanovic@gmx.at>
> wrote:
> >>
> >>> Regarding life in trees, how good a glider can
> *Archaeopteryx* have
> >>> been when it had that gap between wing and
> body,
> >>
> >>
> >> I'm not wholly convinced that _Archaeopteryx_
> lacked humeral feathers
> >> (= tertiaries or tertials). ÂModern birds have
> three or four of these,
> >> proximal to the innermost secondary feathers.
> ÂHowever, no known
> >> _Archaeopteryx_ specimen exhibits feathers
> associated with the
> >> humerus. ÂFor example, the flight feathers in the
> Berlin specimen
he
> elbow, where the
> >> feathers stop dead: no tertiaries. ÂThis has been
> cited in support of
> >> the flight surface of _Archaeopteryx_ being
> discontinuous, with a gap
> >> between the wing and the body wall where the
> tertiaries would
> >> otherwise be (e.g., Garner et al., 1999 - the
> "Pouncing Proavis"
> >> model).
> >>
> >>
> >> However, two things make me skeptical about this
> interpretation.
> >> Firstly, some crown-group birds from the Messel
> are also found without
> >> tertiaries preserved, although the outer flight
> feathers are clearly
> >> preserved. ÂIn these cases, the absence of
> tertiaries is certainly
> >> preservational. ÂSo the same may be true for
> _Archaeopteryx_.
> >> Tertiaries were likely not as firmly attached to
> the wing as primaries
> >> and secondaries, and may have come loose.
> >>
> >>
> >> Secondly, Mayr et al. (2007) mention what could be
> evidence of
> >> tertiaries in the "Tenth Archaeopteryx". ÂThey
> describe "marked, fuzzy
> >> furrows at the âelbow jointâ which may stem
> from the tertiaries". ÂAs
> >> positive evidence goes, this is admittedly weak.
> ÂBut overall, I
> >> wouldn't write off the possibility that
> _Archaeopteryx_ had
> >> tertiaries, and therefore the wing was complete,
> right up to the body
> >> wall.
> >>
> >>
> >>
> >> Cheers
> >>
> >> Tim
> >>
> >
> 
> 
> Jason Brougham
> Senior Principal Preparator
> Department of Exhibition
> American Museum of Natural History
> 81st Street at Central Park West
> 212 496 3544
> jaseb@amnh.org
> 
>