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Re: Campbell's even crazier than a MANIAC? (archeopteryx climbing)

----- Original Message -----
From: "don ohmes" <d_ohmes@yahoo.com>
Sent: Saturday, September 27, 2008 1:55 PM

They don't call them "basic principles" for nothing.

Nobody calls anything a basic principle. "Basic principle" is not a technical term and does not have a definition. There is no official list of basic principles.

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."

Er... no. For natural selection you don't need any competitors at all, just a population and an environment which may or may not contain competitors. And "only" contradicts "relevant to evolution from the perspective of natural selection"!

The mechanical hurdles to which I refer are not mere
postulates, incidentally - the specific structure and
planform of many living gliders is such that rapid
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"!!!

"Theory has been wrong before, so it can be safely ignored"? Surely that's not what you are trying to say?

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.

What exactly would those control motions look like, and how could they evolve into flapping?

I use the behavior of the common anole as a base model, even though they are not bipeds.

And even though they are much better climbers than just about any maniraptoran.

Is this a good time to point out that earliest known birds, bats and ptero's all had long tails and wing claws

Well, no. That's because possessing these features is _normal_. They are _plesiomorphies_ -- retained character states.

For over a century, people looked at *Archaeopteryx*, saw the finger claws, and thought "wow, how utterly weird, a bird with finger claws! Surely these claws must have been a very special adaptation!" This is completely backwards. Having finger claws is normal for birds (and amniotes in general). Archie is normal, *Confuciusornis* is almost normal, and the Ornithothoraces are the weird ones, despite counting some 12,000 species. The presence of maniraptoran-style finger claws in Archie _does not need an explanation_; what needs an explanation is the _reduction_ of these claws that happened later.

Same for the loss of finger claws in *Nyctosaurus* and bats other than *Onychonycteris*, and for the loss of the long tail in anurognathids, pterodactyloids, most bats (though a few long-tailed bats still live), and avebrevicaud[at]ans.

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. 

OK, that's at least testable.

> 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

Forget about it. There are not enough clades of flying animals to do statistics with that.

Now, the clades of gliding or parachuting animals on the other hand...