Re: The origin of flight: from the water up (still short!)

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

----- Original Message -----
From: "Edels" <edels@email.msn.com>
Sent: Wednesday, March 27, 2002 9:40 PM


> David has proposed (or more properly, echoed a proposal) that the
feathered
> maniraptors

Probably not most known ones, though. :-)

> spent some time in the water - significant enough time to allow
> them to learn the flight stroke by 'flying' in the water, which they then
> used the same way when they were in the air - therefore: powered flight.

Yep.

> David's assumptions about the way the maniraptors would behave in the
water
> are based, it appears, on the idea that many animals move much more slowly
> in water [...].

Well, I basically said (parroting from Ebel) that Archie's tail may have
been used for steering, and was stiff enough to be used in water where drag
and all dynamic pressures are higher (at the same speed); that's why it's
stiffer than the tail of a flying squirrel. (Thanks to HP Jaime Headden for
his post which cleared some things up for me.)

> AFAIK, _Archaeopteryx_ did not appear to have the stiffening structures
> (ossified tendons) that some dromaeosaurs had, and the tail feathers do
not
> appear to be solidly interlinked.  This would seem to indicate that the
tail
> was somewhat flexible and not necessarily rigid, as proposed.

I was exaggerating (as usual in physics) when I compared it to a stiff
plate. But it does seem to have been pretty stiff, though less so
dorsoventrally than laterally, as seen in the specimens.

> I don't think the FUCHSIA scenario brings much to the table, other than a
> possible means of learning the flight stroke.

This is _all_ I intend it to do! :-) The full-blown arboreal scenario aims
to explain endothermy, feathers, wings, and the flight stroke at once; in
contrast, I use an extra scenario for each of these "steps". (Though
feathers must have come very soon after endothermy, or partly in concert.)
When FUCHSIA, aimed solely at explaining the flight stroke, can additionally
explain a few tail shapes, then fine.

> For one thing, I think that Archie was fully
> capable of flight, even with his long bony tail.  'He' may have been
awkward
> compared to modern birds, but I think the flight was there.

I used to think so... but the asymmetry of the wing feathers is outside the
range of all measured flying birds, and in the peak of flightless ones. (The
isolated feather, though, is at the lower end of the known range of flying
birds. Therefore I think it can't have belonged to the same species as the
skeletons. I hope it isn't the type specimen?)

> Feduccia even
> calculated that Archie could fly - even without endothermy.

Ruben calculated that Archie, if its flight muscles made up 7 % of body mass
(a total guess, Ruben just inserted the first low number he thought of), and
if it was ectothermic, was capable of flying for a few seconds, if it then
rested for at least half an hour. That's a bit much. In that time it was
defenseless. Well, a totally feathered ectotherm is rather absurd anyway.
        Ruben's calculation doesn't take into account how asymmetric the
feathers were; and I don't know what wing area he assumed.
        I'm pretty sure at least all Dinosauriformes were endothermic.
*Lagerpeton* may have been transitional (speculation!)... depends on, among
other things, the phylogenetic position of pterosaurs.

> Archie seems to
> be right on the cusp of so many things - just enough energy and feathers
to
> fly either as an endotherm or an ectotherm, just right between birds and
> dinosaurs.

To me, Archie seems to be right in the _middle_ of the early radiation of a
big clade of coelurosaurs, equal in content to most people's
Maniraptoriformes, being very similar to e. g. *Microraptor*,
*Sinornithosaurus* and *Sinovenator*, a full endotherm like everyone else,
and pretty far away from the ancestry of Pygostylia, but now we're getting
into my phylogenetic hypotheses which are a different affair.

> My two point five cents (minor inflation - Have you been to a gas pump
> lately?!?!? :-))

My about 2.27 euro cents. :-)