[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: The origin of flight: from the water up
David Marjanovic wrote:
> Good argument. However, for a bird, Archie's wings
> are pretty short. That's certainly the plesiomorphy
> and therefore rather negative evidence, but it
> isn't evidence against.
To my knowledge, Archie was a poor flier (assuming it
even *could* fly). Putting Archie in water to build up
those flight muscles might be a little like putting a
poor swimmer in a pool full of sand. If it's bad at
one it's probably worse at the other.
I have trouble imagining how such a poorly-adapted
animal could become successful in the ocean.
> Archie wasn't so extremely pneumatic, and dippers
> still do fly around underwater
I doubt we can say how pneumatic Archie was just by
identifying pneumatopores on the bones. Regardless, it
was still a very light coelurosaur.
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'll bet quite something that Archie was a
> considerably worse flier than any dipper.
I would agree. All things being equal though, the
point still stands on wing size. If anything,
underwater flight will boost muscle size and degrade
wing size. 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. 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
On plunge-diving pelicans:
> Why is that telling? Pelicans are big and
> specialized. Many smaller birds don't plunge-dive.
Poor example. My bad :)
> Feduccia says explicitely that they flap in the
> waves. And I've seen several
> seabirds (gulls?) fly underwater on TV.
No comment on the flapping through waves. And yes,
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.
> Apart from the effects of its size, it must have
> been a much worse climber than I... or than a rat, >
to get closer to its size.
I think HP Jaime Headden has shown a possible method
of climbing in small dromaeosaurs. I don't see why
these animals would make poor climbers at all. There
are adaptations that can be interpreted as arboreal
even. No need to list them now - they've already been
> 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. What purpose would you invoke using the
> Chatterjee has proposed the same... I think
> undulatory flight can only arise
> in a fully capable flapper, it just looks too
> difficult for me. :-)
I doubt that many behavioral changes would be needed
to simply make a gliding maniraptor angle it's wings
up periodically (I'm not talking about flapping, but
the parasagittal axis of the wings). The mental
hardware would already be there if it was able to
guide its flight path. 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. Note that when the wings are brought back to
horizontal that the animal would "hop" higher into the
air, giving it a boost.
> Possible. But maybe just prey was held against the
> ground. I'd still expect longer halluces inserting >
farther down for this purpose.
And we do see that in more derived birds. They've just
> 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. I hope your model is testable....
> > 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.
> 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.
I see. Might be as superficial as my owl
analogy....but who knows.
Do You Yahoo!?
Yahoo! Movies - coverage of the 74th Academy Awards®