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

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

> > There was once a camp saying that its muscles weren't big enough. I
> > don't know whether it still exists.
>
> Well, it's the camp responsible for reference 2 in your original
> message, right?  That's J. R. Speakman, Evolution 47, 336 -- 340 (1993)

Probable. As I wrote I haven't read any of the refs. I'm just presenting the
paper :-)

> > > How does this mean it's incapable of gliding?  Surely that needs
> > > neither the muscular power required for flapping flight, nor the
> > > wrist shape required for the flapping stroke?
> >
> > As I wrote, perhaps not clearly enough:
> >
> > >> gliding birds (7 species from 7 families) are wholly within the
> >    range for flappers. <<
> >
> > They have the same wing feathers as flappers. So, judging from the
> > feathers alone, a bird can either both flap and glide, or none;
> > Archie is out of this range but within that of flightless birds.
>
> 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?

> In fact, come to think of it, this whole feather-asymmetry thing is
> nothing more substantial than guilt-by-association.  Given that Archie
> was more primitive than modern birds, we'd expect it to be less well
> adapted to flight than they are.

Less well adapted than _any_ of them are? Unfortunately they don't write
which 78 families of birds they measured, but I'd be surprised if they
didn't take a tinamou. 1.46 is far from 2.22.

> > "Vane asymmetry averaged 1.44 for the London specimen and 1.46 for
> > the Berlin specimen [...]