Re: Sort Your Story Out! (Was: 2 refs that were once new...)

["David Marjanovic" <david.marjanovic@gmx.at>]

----- Original Message -----
From: "Tim Williams" <tijawi@hotmail.com>
To: <david.marjanovic@gmx.at>; <dinosaur@usc.edu>
Sent: Thursday, September 20, 2001 11:20 PM


> David Marjanovic wrote:
>
> > > I don't think this proves anything.  The fact that modern gliding
> > > birds have asymmetry within the range of modern flying birds is purely
> > > circumstantial -- plus it's the sort of convergence you'd expect,
> > > since an aerodynamically efficient feather is aerodynamically
> > > efficient whether used for flapping or gliding.
> >
> >So Archie didn't use its feathers for anything aerodynamic, no?
>
> If _Archaeopteryx_ used its wing feathers for passive gliding, then the
> feathers still served an *aerodynamic* purpose.  The issue here is what
sort
> of aerodynamic purpose these feathers were used for.  I find it difficult
to
> believe that long, planar, asymmetric, closed-vaned feathers were
originally
> developed for a non-aerodynamic purpose (brooding, display, whatever) and
> only later were put to use in aerodynamic locomotion.

The paper says that the feathers were exactly _not_ asymmetric (enough) for
_any_ aerodynamic purpose. *Archaeopteryx* is within the range of flightless
birds and outside of the ranges of both flappers and gliders. Gliders are
within the range of _flappers_, not that of non-fliers. So, if this paper is
worth something (and didn't, say, severely undersample gliders), then Archie
was neither a flapper nor a glider.

This doesn't falsify the "Pouncing Proavis" model (that _I_ dislike for
other reasons). It doesn't even falsify Feduccia's traditional parachute -->
glide --> flap scenario. Of course it says nothing about Archie's
phylogenetic position. It just strongly suggests that Archie neither glided
nor flapped.

> One proposal is that the wings of _Archaeopteryx_ were only useful for
very
> short flights.  The wing was used for lift and propulsion by flapping
(i.e.
> powered flight), but the pectoral musculature was insufficient for
sustained
> flapping.

I think they must have included some birds that fly rarely and only short
distances (such as pheasants or tinamous); I don't know, however, because
they just don't write what their 71 species of flappers are.