Re: The origin of flight: from the water up

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

----- Original Message -----
From: "Waylon Rowley" <whte_rbt_obj@yahoo.com>
Sent: Wednesday, March 27, 2002 7:30 AM


> I doubt we can say how pneumatic Archie was just by
> identifying pneumatopores on the bones. Regardless, it
> was still a very light coelurosaur.

It certainly wasn't as pneumatic as most neornithines who have air in their
sternum, furcula, ilia...

> In regards to Dipper wings:
> > Sure? Even stubbier than Archie's?
>
> Hard to tell from online pics because they all show
> them with wings folded, but Dipper's do appear to have
> smaller wings, or smaller primaries at least.

I'd appreciate a URL.

>  If we were talking about tiny
> hummingbird-sized maniraptors, FUCHSIA might make more
> sense, but there is just too much drag and resistance
> on a larger animal.

Maybe we are talking about at least blackbird-sized ones, considering how
small *Microraptor* was and considering the quality of the fossil record...
:-)

> If flapping flight began
> underwater, I would imagine the entire body moving up
> and down with each wingbeat as a result of this
> resistance. If your body has less resistance than your
> enormous wings, then you aren't going to be moving
> much.

Should depend on the exact shape of the wingstroke... and the shape of the
body... at least such mechanical issues are testable.

> I've seen the gulls diving and flying down into
> "bait-balls" of sardines on TV as well. They appear to
> me to be having trouble doing so.

Gulls have very long, narrow wings, compared to Archie.

> > On the published photos, the hallux isn't longer
> > than Archie's, seems to originate at the same
> > height above the other toes as in Archie, and is
> > disarticulated from the metatarsus
>
> I can say that this characteristic is useful in
> climbing.

I can say it hasn't reached the threshold beyond which it would be useful in
climbing. -- Testable.

> What purpose would you invoke using the
> FUCHSIA model?

None at all. :-)
Only one species of gull, *Rissa tridactyla*, has lost the hallux, BTW; this
species walks very little, but breeds on rocks, so some perching ability
might be considered useful.

> The formula is simple: jump,
> fold wings, extend wings, angle wings up, raise wings,
> bring wings back to horizontal. How hard is that? Most
> of it would already be employed by conventional
> gliders.

It would descend in a stair-shaped path: parachute-glide-parachute-glide...
IMHO this is the most complicated method to get from A to B in a forest,
short of climbing down the tree and climbing up the other. I think it might
bring about the flight stroke to such an animal's distant descendants, but
no profit to itself. Does any living glider do this?

> Note that when the wings are brought back to
> horizontal that the animal would "hop" higher into the
> air, giving it a boost.

A weak origin for the downstroke... Is this testable? :-)

> > This is outside the realm of FUCHSIA. =8-) I think
> > arboreality came later, after flapping flight on
> > the level of *Confuciusornis* and/or *Sapeornis*
> > had evolved.
>
> So what should we expect to see in a bird "fresh out
> of the water" as far as adaptations go? Do *C.* and
> *S.* display them, or any other primitive birds
> excluding Archie? You said that the semiaquatic
> interlude was brief, so we shouldn't expect many
> changes at all.

Yep. We might actually expect nothing. I don't think the diving behavior of
a fossil dipper could be found out, unless at least the nostril flaps are
preserved...
Oh, wait. A "bird fresh out of the water" should be able to fly. And indeed,
*C.* and *S.* could, and so could *Rahonavis*. :-)

> I hope your model is testable....

The biomechanical and hydrodynamic issues should be. For testing whether it
actually happened, rather than just being possible, we'll need a
tremendously improved fossil record, something like Messel or Sihetun, of MJ
or EJ age... and, see above, even that may not be conclusive.

> > > Birds simply flew out of the water, landed on a
> > > perch, and by a macromutation miracle modified
> > > this appendage?
>
> > Erm... yes, basically, but that took some Ma... :-)
>
> Right. But unless the hallux touched anything in the
> post-aquatic birds it wouldn't receive any
> evolutionary "stimulus" to change.

True. I have pretty little to say about that. I have yet to think up an
explanation :-)

> > I think *Rahonavis*, with its very long wings and
> > legs, had specialized into
> > a secretary bird analogue that, unlike a secretary
> > bird, didn't need to kill its prey with its jaws.

Anyway, it must have been a pretty good flier, and must have evolved this
ability (as seen from e. g. the mobile scapula-coracoid joint) independently
of Ornithothoraces. Amazing convergence. -- When you ask me, Paraves should
be anchored on it. :-)