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Re: Campbell's even crazier than a MANIAC? (archeopteryx climbing)
--- On Sat, 9/27/08, Michael Habib <firstname.lastname@example.org> wrote:
> Competitive exclusion is indeed a well-established concept
> in biology,
> but so is the knowledge of mechanical constraints.
> Besides, being a
> "basic principle" does not make a given factor
> more likely.
> Competitive exclusion is notoriously difficult to
> demonstrate, in fact,
> and it is still uncertain how important it is in
> evolutionary patterns.
They don't call them "basic principles" for nothing. Perhaps "competitive
exclusion" has some modern meaning I am unfamiliar with, so I will substitute
the term 'competitive superiority' in it's stead. It is an essential component
of the natural selection concept, and a reality familiar to everyone. Mechanics
are only relevant to evolution from the perspective of natural selection, so it
is considerably more accurate to say "Mechanics are notoriously difficult to
demonstrate, in fact, and it is still uncertain how important they are in
determining specific evolutionary patterns."
> The mechanical
> hurdles to
> which I refer are not mere postulates, incidentally - the
> structure and planform of many living gliders is such that
> oscillations of the airfoils would have a negative impact
> on vorticity.
True, but sometimes theory is misleading. Solar thermal power is more
"efficient" than photovoltaic panels (PV), for example. So when Google funded
(partially) a 720 acre solar power plant in the Mojave they naturally went w/
solar thermal. However, the concentrators must be washed w/ water twice a week
to maintain that "efficiency"!!!
PV panels, otoh, are virtually maintenance-free. It follows that a 100 sq mi
grid of PV is technically feasible, whereas maintenance of even 720 acres of
the more "efficient" troughs may not be doable longterm.
No flying squirrel will ever increase glide length by waving it's paws in
mid-flight, but it is possible for selection to enhance control motions that
occur at the end of the glide.
This logically has special implications for perch-hunting/terrestrial pursuit
bipeds. I use the behavior of the common anole as a base model, even though
they are not bipeds. They like the safety of high places, yet fling themselves
at terrestrial prey from heights of several meters. If they miss, they chase
enthusiastically, although they do not persist.
They are small, so they have no need for aerodynamic effect. Were they to
increase in size, a step-wise sequence of braking/gliding/flapping is
straight-forward in theory. Again, I point out the 'climber-friendly' nature of
cycads, and also that little lizards will likely remain lizards, unless the
birds are somehow wiped out.
> The origin of flight in pterosaurs is currently equivocal. Actually, I >
> consider the origin for pterosaurs to be
> currently equivocal, as do most pterosaur workers. It is
> plausible that arboreality could have been involved - but
> it didn't
> have to be.
Is this a good time to point out that earliest known birds, bats and ptero's
all had long tails and wing claws, and that some trees are really easy to climb?
> They may have had competition from pterosaurs, however (in
> terms of
> flying groups), and there were certainly plenty of small
I did not say that there was no competition. I continue to assume that the
competitive barriers faced by proto-birds as they achieved lift-off were less
than they would face in an environment filled w/ real birds. And bats.
> > Heh. Oh, do you have an example of "terrestrial
> origins for flight"? :D
> As mentioned before, birds may very well be an example.
Or not. There is debate about that... :D