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Re: The Peters Strikes Back (pterosaurs)
Darren Naish wrote:
-- Wing membranes. At the moment the bulk of the
evidence indicates that extensive wing membranes are more
likely than narrow-chord ones.
>> A bulk of evidence would be great! But I'm looking for one example.
I am particularly impressed
by data showing a correlation between fore- and hindlimb
lengths: this is Elvidge and Unwin's data (see new JVP
abstract volume, p. 48A).
>> You can have fore and hindlimb correlation and also have a decoupled wing.
As usual, I know that anecodates
don't count for much, but I have seen an unpublished
(azhdarchoid) specimen at Karlsruhe which appeared to
show an extensive wing membrane.
>> Then someone in Karlsruhe gets the steak dinner. Get us together! I'm
>> metaphorically holding my breath, but previous such examples have not proven
>> valid. I am _not_ being sarcastic when I say: I would genuinely like to see
>> a deep wing membrane. And a pteroid sticking out anteriorly insitu. And a
>> plantigrade dimorphodontid track. And a pterosaur egg. (Wouldn't we all!)
>> Evidence is what it's all about.
I am far from convinced
by your interpretations of specimens as shown in, e.g., your
_Historical Biology_ paper. Let me emphasise to you
(again) that I have gone into the whole pterosaur issue
open-minded and without any original preference for any
particular view of pterosaur life appearance and phylogeny.
Unwin did cast a few spells and utter some subliminal
things down the telephone but they didn't sway me...
>> I appreciate your open-mindedness. What didn't convince you?
But the point alluded to in the quote is
that, so far as we know, pterosaurs did not radiate as miriad
passerine/microbat-like forms.. in other words there is
"Little indication that pterosaurs radiated as small forms of
terrestrial environments, as both birds and bats did". Ok
there are anurognathids and whatnot but, well, I don't think
you can reasonably disagree with this statement.
>> I wasn't thinking in terms of aquatic versus terrestrial. Thank you
for clearing that up for me. And not to be argumentative here -- while I agree
that there does
appear to be a definite tie to the water in non-dimorphodontids,
that still leaves a number of dimorphodontids (and their numbers are
-- Quadrupedality vs bipedality. Sorry Dave, while I'm
happy for facultative bipedality in pterosaurs, assorted lines
of evidence show that quadrupedality is presently better
supported. The lizards you cite do not have the same CoG
problems that the pterosaurs do.
>> What sort of ptero/lizard CoG problems are you referring to? Perhaps we
address these issues?
Your implication that
people in this generation (whatever that means) are ignoring
what you say is unfair: people might be disagreeing with
you because you might be wrong, not because they're
blinkered or stupid.
>> The problem might be that no one has argued against
my hypotheses, either privately (in my presence) or in press. I gave a damn good
argument that, although it came out of an unexpected an overlooked corner,
it answered a lot of questions. So I'm left wondering... (is it my breath?)
Hind limb diversity: compare big-footed Pterodaustro to
Entirely valid BUT pterosaur hindlimb diversity is still
lower than that seen in decoupled birds. That's the point.
>> You're assuming that pterosaur hind limbs are coupled. Hind limb diversity
>> -- or
_any_ kind of statistical analysis might not show that. Only _evidence_ can
Re: pterosaur ancestry, yes personally I agree with you that
prolacertiforms appear to be the most likely ancestors of
pterosaurs. But more data is still needed for us to be
confident about this and I note that some pterosaur workers
are still luke-warm to the idea.
>> Why is this so? What's the counter-argument? What's the better hypothesis?
I'm totally in the dark on this. I _know_ it's not Scleromochlus.
I do not however agree with
your interpretation of prolacertiforms as dinosaur-like
>> Only to the extent that, like little dinosaurs, they could run bipedally.
>> From a distance, if
you weren't able to determine the greater sprawl of the femora, you might
mistake one for
a little dinosaur.
Re: _Cearadactylus_ nested with ctenochasmatoids...
This should have been Dr. Unwin's clue that this could not
Ah, you have magic powers too? I thought the purpose of a
cladistic analysis was to produce results based on data, not
to show what is intuitively most satisfying.
>>> The results are from my own cladistic analysis, Darren. Almost 180
>>> characters and 90+ taxa. And
I've often seen that when something doesn't seem right, it needs to be further
investigated. I understand
Dr. Unwin's situation more than you might realize, however. The most difficult
part of the pterosaur cladogram
to figure out is the basal pterodactyloid situation. I struggled a long time
with the problem until it all crystalized.
And I'll send you the data, if interested.
Re: While virtually nothing is known about
> This will be known soon.
Err, yeah. Having seen the evidence for your pterosaur
babies Dave all I can say is.. good luck convincing
>>> While some embarassing over enthusiam did occur early on, the quest did
>>> turn up
some valid results in the past few weeks -- that you haven't seen. No one bats
And, hopefully to my credit, I acknowledged those early errors.
All the best and, hey, no hard feelings:)
>> It'll all come out in the wash. I'm having too much fun to quit. Will you be
>> at SVP? I'm sure you
don't want to miss out on the fun when I reveal the Chinese vampire to a
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