The Peters Strikes Back (pterosaurs)

[darren.naish@port.ac.uk]

Thanks to David (P) for his comments on the pterosaur 
article. Sorry Dave, didn't think you'd like it... I don't have 
time to deal with all of your points in turn but here are quick 
responses...

-- Wing membranes. At the moment the bulk of the 
evidence indicates that extensive wing membranes are more 
likely than narrow-chord ones. 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). 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don't count for much, but I have seen an unpublished 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. 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...

-- Re "Little indication that pterosaurs radiated as small 
forms of terrestrial environments, as both birds and bats 
did". In response David writes....

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This line from the text is confusing. Pterosaur tracks attest 
to the fact that at least some pterosaurs walked and fed in 
terrestrial environments (unlike bats, other than, perhaps the 
vampire). If instead this refers to bird and bat origins (as 
dinosaurs and as [insectivores? dermopterans? primates?] 
respectively) then from which non-terrestrial diapsids did 
pterosaurs come? -- if both small pre-dinosaurs and small 
prolacertiforms are respectively rejected and ignored?
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Pterosaur ancestry is irrelevant here: sure, pterosaurs 
evolved from ancestors that lived in terrestrial environments 
(BTW, the term 'terrestrial environment' is key here. 
'Terrestrial environments' are the opposite to 'aquatic 
environments', and the latter include lakeshores, mudflats, 
littoral areas, etc). 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.

-- 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. 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.

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Hind limb diversity: compare big-footed Pterodaustro to 
tiny-footed Anhanguera.
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Entirely valid BUT pterosaur hindlimb diversity is still 
lower than that seen in decoupled birds. That's the point.

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. I do not however agree with 
your interpretation of prolacertiforms as dinosaur-like 
bipeds.

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Re: Basal pterosaurs exhibit: a dorsoventrally shallow body

> no more so than any other diapsid or later pterosaur
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The statement does not imply that a dorsoventrally shallow 
body is _unique_ to basal pterosaurs. Similarly, the other 
basal pterosaur features we cite (curved manus claws etc) 
are not meant to be _unique_ to basal pterosaurs, just 
common to them. Credit where credit's due: most of the data 
here is from Chris Bennett's 1997 article on pterosaur 
ancestry (_Hist. Biol._ 12, 265-90).

Re: _Cearadactylus_ nested with ctenochasmatoids...

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This should have been Dr. Unwin's clue that this could not 
be true.
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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.

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Re: While virtually nothing is known about
pterosaur reproduction

> This will be known soon.
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Err, yeah. Having seen the evidence for your pterosaur 
babies Dave all I can say is.. good luck convincing 
everyone else.

All the best and, hey, no hard feelings:)

-- 
Darren Naish
School of Earth & Environmental Sciences
University of Portsmouth UK, PO1 3QL

email: darren.naish@port.ac.uk
tel: 023 92846045