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Re: Feathers vs patagia

> David,
>      Well, I do look forward to seeing your paper.

So do I  B-( . I've just mailed to the editor asking what has happened
(maybe it is published, and snail-mail just hasn't carried it to me yet).

> However, I'm not sure your objections to Larry's ideas are necessarily
> valid.

How could you (nitpicking)? This is neither mathematics nor logics... ;-)

> He isn't saying that birds evolved from any of the advanced
> pterosaurs you are describing, but forms which were far more primitive
> haven't been found (or perhaps sitting unrecognized in some museum
>      I can contemplate such an ancestral form (perhaps a little more
> pterosaur-like than birdlike) gliding from gymnosperm to gymnosperm (be
> cycads, conifers, or some other gymnosperm). One line goes the pterosaur
> route, another goes the bird route, and the intermediates go extinct. And
> if I understand Larry's ideas correctly, theropods are secondarily
> flightless birds (in agreement with BCF theories).

Oh. OK. Still I think the transition from a glider to a (flapping) flier is
next to impossible for physical reasons. I must admit that I don't have a
better idea on how bat flight evolved than from gliding, but anyway we'd
expect to see a large brachiopatagium in birds instead of wing feathers.

>      I don't know if pterosaurs and birds had a primitive gliding common
> ancestor, but I think it is a good idea to investigate such possibilities
> (just as you are apparently doing in developing some other possible
> scenarios).  Whether Larry is wrong or right, I don't think his reasoning
> teleological, at least in the ways you seemed to be pointing out.  If they
> do have a common gliding ancestor, I suspect it would be more
> than birdlike.  Anyway, looking forward to your paper.
>                     -----Ken

I don't want to accuse him of spreading teleological beliefs, I only think
that he might (as I have repeatedly) have run into this trap without noticin
g it. I just can't think of any selectionary pressure leading to the
reduction of a sophisticated wing membrane (more complicated than in bats)
in favor of wing feathers; more on the improbability or impossibility of the
glider-flier transition in my paper :.-( and the references cited therein,
like the paper by Klaus Ebel, the ref of which I have sent to the list
yesterday (or today in the morning, on some other continents). (In this
paper, there's the maths and physics!)

However, I think HP Larry Febo has noticed some valid synapomorphies of
Ornithodira (Pterosauromorpha + birds sensu BCF). He has just mentioned
offlist that the supporting rods of pterosaur wings are keratinous and
hollow like feather keels; this supports the hypothesis (developed on this
list, I think) that protofeathers are a synapomorphy of Ornithodira and that
pterosaur hairs and wing rods may be feather keels. The difference between
our hypotheses in this point is little more than character polarity.


May G. W. Bush stay US president for long B-) . Exactly since he has been
designated (rather than elected...), the Euro is rising (I won't speculate
here about the causes B-) ). Yesterday it was already at 0.9543 US$,
tendency further rising... Ordering books at Amazon thus becomes cheaper and
cheaper. :-)