Last response to Dave Peters; goodbye DML

[darren.naish@port.ac.uk]

Re: David Peters? most recent batch of comments on the 
_Biologist_ pterosaur article (Naish & Martill, 2003), here?s 
a belated response. As usual it?s coming a bit late, but the 
lateness might be useful seeing as Dave (and other 
interested parties) should by now have returned from SVP 
(hope it was fun).

On wing membranes I wrote?

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At the moment the bulk of the evidence indicates that 
extensive wing membranes are more likely than narrow-
chord ones. 
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In response Dave wrote?

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A bulk of evidence would be great! But I'm looking for one 
example. 
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Dave, I mentioned in my previous email the Brazilian Crato 
Fm azhdarchoid I?d seen at Karlsruhe: an azhdarchoid that 
(so far as I can remember) preserves a brachiopatagium 
extending to the ankle. Dino seems to think this is the case 
too as he said as much at SVPCA 1999 (Edinburgh): I?m 
not sure, but there may be more info on this specimen in the 
new Buffetaut & Mazin volume (and I know this is out now 
because reprints started arriving last week). Regardless, 
some nice photos of the specimen are published in Friedrich 
Pfeil?s 2001 book _Drachen der Lufte. Entwicklung und 
Leben der Flugsaurier_ (Jura-Museum Eichstatt, pp. 48). 
The specimen?s left leg and elbow region are shown in 
detail in Fig. 1 of Tafel 9, and a close-up of the animal?s 
foot is shown in Fig. 2. In both figs an extensive 
brachiopatagium inserting AT THE ANKLE is shown. I 
don?t eat steak: pasta would be nice:)

On incorporation of the hindlimb into the brachiopatagium, 
I wrote?

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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). 
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And in response Dave wrote?

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You can have fore and hindlimb correlation and also have a 
decoupled wing.
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True, but given that the correlation occurs in all measured 
pterosaurs (and therefore spans all of reported pterosaur 
phylogenetic diversity), isn?t it a bit suspicious that there 
aren?t any pterosaurs in which fore- and hind-limb lengths 
are not significantly correlated? The pterosaur pattern is in 
marked contrast to that of birds where there is a far looser 
correlation between fore- and hind-limb lengths. The data 
I?m basing these assertions on are, by the way, those of 
Elvidge & Unwin, as now presented at several meetings 
(Toulouse meeting, SVPCA Cambridge, SVP 2003). For 
previous comments on this see my brief discussion of 
Unwin?s SVPCA 2002 presentation at?
http://www.cmnh.org/dinoarch/2002Sep/msg00345.html

? and also?

Elvidge, D. J. & Unwin, D. M. 2001. A morphometric 
analysis of the hind-limbs of pterosaurs. In _Two Hundred 
Years of Pterosaurs, A Symposium on the Anatomy, 
Evolution, Palaeobiology and Environments of Mesozoic 
Flying Reptiles_. Strata Série 1 11, 36.

Elvidge, D. J. & Unwin, D. M. 2003. Locomotor modules, 
linkage and morphological disparity in pterosaurs and other 
flying vertebrates. _Journal of Vertebrate Paleontology_ 23 
(Supp. 3), 48A.

On my non-acceptance of Dave?s soft tissue 
reconstructions, Dave wrote?

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I appreciate your open-mindedness. What didn't convince 
you?
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To put it mildly (and I mean no disrespect), I don?t believe 
it?s possible to glean as much data from the specimens as 
you seem to be able to. Many of the details (concerning 
both osteological identifications and the identification of 
purported soft tissue structures) are down to your 
interpretation, and having (in cases) seen the same 
specimens with my own eyes, I generally do not accept your 
interpretations. _Longisquama_ for example: there is no 
way the specimen preserves the details you?ve reported. I 
have also been influenced by Chris Bennett?s comments?. 
http://www.bridgeport.edu/~cbennett/Critique.html

On the apparent absence of a radiation of small terrestrial 
pterosaurs I wrote?.

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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.
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And in response Dave wrote?

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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 increasing!)
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Granted, but so far as we can tell at present there is still 
"Little indication that pterosaurs radiated as small forms of 
terrestrial environments, as both birds and bats did". How 
many little anurognathids or whatever can you name? I?m 
thinking of five or six genera. Now compare that diversity 
to the number of terrestrial-environment fossil bird and bat 
groups.. Cenozoic bat clades (represented in the fossil 
record) that include or consist of small terrestrial-
environment taxa include pteropodids, emballonurids, 
megadermatids, rhinolophids, phyllostomids, natalids, 
molossids, philisids and vespertilionids, and Cenozoic avian 
clades (represented in the fossil record) that include or 
consist of small terrestrial-environment taxa include 
coliiforms, pseudasturids, psittaciforms, opisthocomiforms, 
cuculids, pteroclids, columbids, strigiforms, steatornithids, 
podargids, nyctibiids, aegothelids, caprimulgids, 
archaeotrogonids, jungornithids, aegialornithids, 
hemiprocnids, apodids, messelirrisorids, bucerotids, 
upupids, phoeniculids, gracilitarsids, leptosomids, 
trogoniforms, sylphornithids, eocoraciids, geranopterids, 
momotids, alcedinids, halcyonids, primoscenids, 
ramphastids, picids and passeriforms.. These are not 
complete lists, plus many of the clades listed here include 
several/multiple fossil taxa. Even if all the pterosaurs you 
have in mind _were_ denizens of terrestrial environments 
there is, as yet, little evidence for anything like the 
extensive radiations seen in microbats and landbirds.

On bipedality in pterosaurs Dave wrote?

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What sort of ptero/lizard CoG problems are you referring 
to? Perhaps we could address these issues?
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Unfortunately I can?t find any maths on this, but if you look 
at any of the lizards that employ bipedality one gets the 
impression that the relatively muscular tail provides an 
effective counter-balance to the rest of the animal, and I 
would think that their CoG is round about the pelvis. Snyder 
(1949) comments on this. Data presented by Sarah Sangster 
indicates that in basal pterosaurs (which are likely to have 
had a more caudally located CoG than pterodactyloids) the 
CoG is too far aft for the animal to adopt a bipedal posture 
unless it was capable of digitigrady, and digitigrady in any 
pterosaur cannot be reasonably supported right now. I 
therefore feel the lizard analogy is flawed and needs more 
work. Having said all that, I still don?t have a problem with 
occasional facultative bipedality in at least some pterosaurs. 

On the apparent lack of response to the conclusions Dave 
has published in his papers, Dave wrote?.

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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?)
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I can assure you that your work has been the subject of a lot 
of discussion behind-the-scenes. I do not think however that 
your papers are going to be much cited or discussed by 
other pterosaur workers though. Why? Well, let me say 
again that I mean no disrespect, nor do I want to be nasty, 
but the problem is that your conclusions are based on your 
controversial interpretations (see above). It may be that 
established pterosaur workers do not want to spend their 
time refuting arguments that they regard as being based on 
erroneous data. An interesting thing I have learnt in 
academia (specifically, from Martill) is that workers will 
often not bother to publish a refutation of another worker?s 
conclusions, even if they disagree strongly: this is not 
because they?re lazy, dispassionate or uninterested, but 
because life is too short and they have too much of their 
own research to get into print.

Re: pterosaur ancestry, I wrote?

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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. 
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And in response Dave wrote?

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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.
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Firstly, you do not '_know_' that it's not _Scleromochlus_: 
what you mean is that, so far as you tell right now, 
_Scleromochlus_ is unlikely to be the closest taxon to 
Pterosauria. As you know there are presently three 
hypotheses of pterosaur affinity; (1) prolacertiforms [e.g., 
Peters 2000]; (2) basal archosauriforms [e.g., Bennett 
1996]; and (3) ornithodires [e.g., Sereno 1991). So there are 
counter-arguments to the prolacertiform school. As you 
know, I personally favour prolacertiforms, but given that 
some noted pterosaur workers are still, as I said, luke warm 
to this idea, I still feel the need for some caution, especially 
so given that I?m not a pterosaur specialist myself. 

On pterodactyloid phylogeny Dave writes?

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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.
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Thanks for the offer ? I certainly am interested, but had 
better call an end to things here as I need to focus on the 
theropods I?m supposed to be working on. On that note, this 
is going to be my last DML email for quite some time. 
There?s a little academic project I have to get out of the way 
within the next two years and unfortunately I need to leave 
the list in order to become a more productive person. See 
you all on the other side?.

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

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