More pterosaur gossip

[Unwin <h0662eka@rz.hu-berlin.de>]

More pterosaur gossip

I fully support Chris Bennett's comments on the Toulouse pterosaur 
meeting (glad to see you made it home OK, Chris) and would also like to 
thank Silvio Renesto for his reports on the meeting. The idea that 
pterosaur workers never agree about anything ever is a bit of myth 
(though useful when seeking funding or trying to get a paper published) 
and the truth is that a consensus is being reached in some important 
areas such as terrestrial locomotion, i.e. they were quadrupedal 
plantigrades with an effective gait (e.g. Unwin TREE 14(7), 263-268 
(*ssp)). 

The recognition of pteraichnid tracks as those of pterosaurs has been a 
fantastic help in understanding these bizarre animals and the Crayssac 
site is surely the most important pterosaur ichnolocality in the world 
(certainly for me it was the highlight of the meeting). I understand from 
Padian's presentation at the meeting that he accepts that the Crayssac 
tracks are pterosaurian, but continues to argue that all other 
pteraichnid tracks were made by crocodiles, as he and Olsen first 
proposed in 1984. The problem is that the Crayssac tracks look just like 
all the other pteraichnid tracks (now reported from 30 or so Jurassic and 
Cretaceous sites from all round the world), and share a suite of unique 
features in common with them - even down to the phalangeal formulae which 
are clearly visible in some of the prints we examined at Crayssac as well 
as at other sites in Spain and North America. How then can the Crayssac 
tracks have been made by pterosaurs and all the other tracks by 
crocodiles? Is this some sinister plot by crocodiles to delude 
pterosaurologists? Obviously not. Padian's splitting of pteraichnid 
tracks into two groups is untenable and merely obfuscates the real issue 
- who made pteraichnid tracks? Except that this issue is now pretty much 
resolved - it was pterosaurs what done it - and about the only piece of 
evidence we don't have to support this is a dead pterosaur at the end of 
a trackway - stomped by a short sighted sauropod. 

Big questions remain, however, most notably with regard to the origin of 
pterosaurs. I completely agree with the comments made by Chris Bennett 
regarding David Peters' recent paper on a prolacertiform ancestry for 
pterosaurs. Unfortunately, David misinterpreted the skull of 
Sharovipteryx as preserved in ventral view when it is quite clearly 
preserved in dorsal view - consequently his reconstruction of the skull 
is seriously inaccurate and this leads to all sorts of problems with the 
cladistic analysis. In a separate study I tried including pterosaurs in 
various recent analyses of diapsid relationships including Dilkes (1998 
Phil. Trans. Roy. Soc. 353, 501-541) - and they popped out either as 
ornithodirans, or somewhere in or around the 
archosauriform-prolacertiform split depending on the taxa, characters, 
coding used. The bottom line is that right now pterosaurs can be slotted 
into various places in Diapsida and none of these options can be 
confidently excluded. So, if anyone out there has the 
time/funds/interest/requisite knowledge of diapsid anatomy/ enthusiasm 
for air travel/knowledge of foreign languages/diplomatic skills to take a 
crack at this problem, eMail me, or grab me at SVP, presuming that it 
happens and that I can get there. 

Regards

Dave 

*ssp = shameless self promotion


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Institut fur Palaontologie, MUSEUM FUR NATURKUNDE 
Zentralinstitut der Humboldt-Universitat zu Berlin
Invalidenstrasse 43, D-10115 Berlin, GERMANY

Email: david.unwin@rz.hu-berlin.de

Telephone numbers:
0049 30 2093 8577 (office)
0049 30 2093 8862 (department secretary)
0049 30 2093 8868 (fax)
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