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

[Mike Taylor <mike@tecc.co.uk>]

> Date: Thu, 20 Sep 2001 15:56:59 +0200
> From: "David Marjanovic" <david.marjanovic@gmx.at>
> 
> > 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.

Well, it's the camp responsible for reference 2 in your original
message, right?  That's J. R. Speakman, Evolution 47, 336 -- 340 (1993)
(See http://www.cmnh.org/fun/dinosaur-archive/2001Sep/msg00494.html)

> > 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.)

I struggle to understand that too.  The Paladino, Spotila and Dodson
chapter offers some arguments for thinking that dinosaurs generally
may have been ectotherms, but seems to assume for no reason that I can
see that the ecto->endo transition occurs further down the line than
Archie.  (Oh, alright, before some arch-pedant picks me off, they
assume that it occurs on the branch from MRCA(Archie, modern birds) to
modern birds.)

> > 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.

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.

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

On a different note, I whizzed around the dinosaur hall of the Natural
History Museum on Tuesday evening, keeping an eye out for the London
_Archaeopteryx_ which I think I read recently is held there.  Couldn't
find it.  Anyone know what the story is there?

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