More on Sharovipteryx

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

More on Sharovipteryx

Anatomy:
The elements described by Sharov as parts of the forelimb cannot be confirmed 
as such. So, we cannot actually say anything realistic about how long or short 
the forelimbs really were. In addition, S. had extensive membranes that were 
anterior to the hind limb as well posterior as Sharov correctly showed in his 
original paper. 

Functional morphology:
So far, all authors agree that S. was a glider. Arboreal usually tags along, 
but, as many people have already pointed out, lots of arboreal forms don't show 
any obvious arboreal specialisations, so, if you want S. to be arboreal thats 
OK, and if you don't that is OK too. 

Relationships:
Sharov assigned Sharovipteryx to the 'Pseudosuchia', but, recently, Tatarinov 
(1989, 1994) has argued that it is a prolacertiform. My co-authors and I also 
support this view in our chapter in the forthcoming Russian dino book. 

Dave Peters places pterosaurs as a sister group to S. which, presumably also 
means that pterosaurs are prolacertiforms. There is some evidence to support a 
relationship between S. and pterosaurs, and, depending on how you construct the 
data base, you can get pterosaurs to locate as basal archosaurs (as Bennett has 
shown) or even as a prolacertiform sister group (as a former student of mine 
once did). However, a lot more careful analysis of characters is needed before 
the question of the relationships of pterosaurs to other diapsids can be 
clearly resolved. See Bennett, S. C. 1996 The phylogenetic position of the 
Pterosauria within the Archosauromorpha. Zool. J. Linn. Soc. 118, 261-308. for 
an excellent account of the current situation. 

Incidentally, Ken Kinman mentioned pterosaur ankles. It is usually assumed that 
pterosaurs have the 'derived ankle' type, but Kellner and Tomida in their JVP 
abstract for 1993 point out that in a very well preserved specimen of 
Anhanguera the ankle appears to be of the crocodile-reversed type. See also 
Kellner and Tomida 2000. Description of a new species of Anhangueridae... 
National Science Museum Monographs 17 (National Science Museum - Tokyo) for a 
description of this incredible specimen. 

I once looked at Longisquama, but the preservation is so poor I could not 
confirm a lot of the anatomical details described by Sharov. Until better 
material is found not much that is truly useful can really be said about this 
animal. I had the impression that frond-like strucutres were associated with 
the type specimen, but they did not remind me of feathers. For other 
reconstructions and some brief comments on Longisquama see:

Halstead, L.B. 1975. The Evolution and Ecology of the Dinosaurs. London: Peter 
Lowe, 116 pp.

Halstead, L.B. 1982. Hunting the Past. London: Hamish Hamilton, 208 pp.

Haubold, H. and Buffetaut, E. 1987. A new interpretation of Longisquama 
insignis, an enigmatic reptile from the Upper Triassic of Central Asia. Comptes 
Rendus de l'Academie des Sciences Paris, Série II 305: 65-70.

Tschuessi

Dave 

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David M Unwin
Curator for Fossil Reptiles and Birds
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

Tel. numbers:   

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