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

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

> > "Evaluations of muscle power^2 and osteology of the wrist^3 both
> > concluded that *Archaeopteryx* could not sustain powered (flapping)
> > flight, but this is at odds with the asymmetry of its flight
> > feathers, which is indicative of aerodynamic function^4,5.
>
> OK, wait a minute.  Here's the situation.  We have people who say that
> Archie couldn't fly (read "flapping flight"), period.  Then we have
> the camp that says it was endotherminc and therefore able to generate
> enough muscle power to fly.

There was once a camp saying that its muscles weren't big enough. I don't
know whether it still exists.

> And as if that weren't bad enough, you
> then have people like Paladino, Spotila and Dodson (see their _A
> Blueprint for Giants: Do Living Reptiles, Birds or Mammals Provide the
> Best Model for the Physiology of Large Dinosaurs?_ in _The Complete
> Dinosaur_) who claim that Archie, like all dinosaurs, was ectothermic
> but was capable of powered flight anyway!
>
> How can people disagree _that_ badly?  Surely the evidence can't be
> quite so ambiguous?  Can it?

That's what I'd like to ask... (Ectothermy is IMHO nonsense -- poor Archie
would have had to rest for half an hour after seconds of flight.)

> > Means, Archie was incapable of both flapping and gliding.
>
> 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.
        Incapability to glide is consistent with the long bony tail that
should have drawn the center of gravity near the hips (Ebel 1996).
        In the Proceedings of the Royal Society of the last half year there
are 2 papers on the aerodynamic effects of bird tails. Have yet to read
them.

I forgot to quote a few important sentences:

"Only three specimens of *A. lithographica* have the feathers sufficiently
preserved to measure vane asymmetry: the Berlin and London specimens and the
single feather. The single feather has an asymmetry of 2.2 [...], but where
this feather comes from in the wing, and indeed whether it is from the same
species, is unknown^6."

2.2 is still within the range of flightless birds, and just under the very
lower end of flappers (2.22). Whether it is from the same species is now
more doubtful than ever, given the Jurassic birds now reported in
http://www.cmnh.org/fun/dinosaur-archive/2001Jul/msg00067.html.

Ref. 6 is R. Owen, Proc. zool. Soc. Lond. 12, 272f. (1864)

"Vane asymmetry averaged 1.44 for the London specimen and 1.46 for the
Berlin specimen (Fig. 2d [which isn't very detailed, whence comes my wrong ~
1.25 estimate of yesterday :-] ]). The asymmetry in the primary four
feathers of *Archaeopteryx* is not significantly different to that of modern
flightless birds [...] and substantially and significantly lower than that
of modern flying birds (whether flapping [...] or gliding [...])" according
to several statistic tests.