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



--- On Sat, 9/27/08, David Marjanovic <david.marjanovic@gmx.at> wrote:

> 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"!

Er, yes. In reality, there is ALWAYS competition, even in lab.

> >> 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?

You are right, that is not what I was trying to say.

> > 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.

So they are better climbers. So what? You don't have to be optimized to climb 
to successfully climb. Especially cycads.

> 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.

Exactly. And 'they did not need them anymore, at least not enough to counteract 
their negative consequences' is reasonable. The obvious implication is that 
they did need them at one time. The length of time that elapsed before they 
disappeared indicates to me they may have continued to be useful even after the 
wings were formed, or at least that that possibility can't be discounted. 

Don