Re: FUCHSIA and the Ostrom Symposium Volume (long...)

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

----- Original Message -----
From: "James R. Cunningham" <jrccea@bellsouth.net>
Sent: Saturday, August 10, 2002 12:31 AM

> For birds an pterosaurs, it would appear that takeoff from the ground is
> feasible even before wings and musculature are sufficient for powered
flight.

Wow.

> > Why would anyone do that, without knowing a priori
> > that doing so increases speed and/or leads to takeoff?
>
> It generally doesn't lead to an increase in speed (remember my car and
> rope scenario).

I don't. Could you repeat it or find it in the archives? Thanks in advance.

> Also, don't forget that cursorial animals are also likely to have leg
> power enough to get into the air by leaping without being obligated to do
it by
> running.

Basal pygostylians and Archie don't appear to have been really cursorial,
though.

> I remember the chickens on the farm where I grew up using flapping to help
them
> turn, to great effect, particularly when I was chasing them.

Interesting... I don't see how this could lead to flight, though.

> Dunno about roadrunners.  Do they turn much when they are running, or just
go
> like h*** in a straight line?

Never saw one in natura... the one I saw on TV did make some turns and
didn't flap.

> > , and the first takeoffs into the air would have been simply flying out
of the
> > water.
>
> Sounds to me like taking something simple if done from solid ground and
making
> it difficult to the point of improbability.

I'm trying to find a way how they actually got the idea of doing it, of why
an animal with wings etc. whose ancestors have never flown suddenly would
find out that it can fly. This problem is IMHO commonly ignored. (It is
probably easy to explain in the context vertical running... the animal grabs
the tree trunk again and again and as fast as possible to flee upwards, and
finds out that this works even when it fails to reach the trunk and just
waves air around. But before the paper is published and I've read it, I
don't know what obstacles might lie in there.)

> > Jeremy M. V. Rayner: On the origin and evolution of flapping flight
> > aerodynamics in birds, 363 -- 385
> >
> > (- Uses great confidence in an outdated phylogeny to show that bats must
> > have begun as gliders.)
>
> Don't forget that Jeremy has forgotten more about flight than most of us
will
> ever know, and remembers far more than he has forgotten.

Great way to word a compliment :-) -- of course, of course. All I take issue
with is his statement "(the role of gliding in the origin of bats [...]
seems beyond question in light of the close relationship between Dermoptera
and megachiropterans, and the good fossil record ofgliding in Dermoptera
[...])" (p. 365f.) -- according to all new cladograms of Placentalia I've
seen there is no such relationship, Dermoptera is close to Primates and
therefore closer to Rodentia than to Chiroptera which sits around the base
of Laurasiatheria, so no gliding relatives of bats are known.

> I believe Archie did have one, though not particularly well-developed.

A supracoracoideus? The usual assumption is that it had one and many/all
other theropods did, too, but it didn't work like in Pygostylia, instead it
only pulled the arm forward.

> >  A runner that, in the style of Burgers & Padian above,
> > tried to flap wings in the predatory stroke while running would have a
very
> > effective brake. :-)
>
> Would you explain the mechanics of that to me?

When the wings meet in front of the body, a part of the air will be pushed
forwards, thereby pushing the animal backwards. But a second look at Fig. 9
of Gishlick's chapter shows that I was probably wrong, the predatory stroke
is different :-] (Can't see how thrust can come out of this, as opposed to
the wing stroke, either.)