Re: Birds vs. the pterosaurs

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

Birds vs. the pterosaurs

There have been a few papers on this subject. See for example: 

Buffetaut, E., Clarke, J. B. and Le Loeuff, J. 1996. A terminal Cretaceous 
pterosaur from the Corbieres (southern France) and the problem of pterosaur 
extinction. Bull. Soc. geol. France. 167, 753-759. 

Unwin, D. M. 1987. Pterosaur extinction: nature and causes. Memoires Sociéte 
Geologique de France, 150: 105-111.

Unwin, D. M. 1988. Extinction and survival in birds. In: Larwood, G.P. (ed.), 
Extinction and Survival in the Fossil Record. Systematics Association Special 
Volume 34, 295-318, Clarendon Press, Oxford.

and the subject is also treated by Wellnhofer in the Encyclopedia,

Wellnhofer, P. 1991. The Illustrated Encyclopedia of Pterosaurs. Salamander 
Books, Ltd., London, 192 pp. 

Combining our current understanding of pterosaur phylogeny (see for example 
Unwin, D. M., Lü, J. & Bakhurina, N. N. 2000. On the systematic and 
stratigraphic significance of pterosaurs from the Lower Cretaceous Yixian 
Formation (Jehol Group) of Liaoning, China. Mitteilungen Museum für Naturkunde 
Berlin, Geowissenschaftlichen Reihe, 3, 181-206), with a current data base for 
the Cretaceous pterosaur fossil record suggests that pterosaur diversity 
declined in the Late Cretaceous, and, by the Maastrichtian, only a few species 
(practically all of them azhdarchids, were left). Pterosaur bones are quite 
distinctive, and so far none have turned up in post Mesozoic sediments, so it 
looks as if pterosaurs did not make it through the K-T boundary. It is possible 
that birds had some impact on pterosaur evolution. It might be, for example, 
that in the Cretaceous, birds opportunistically filled 'niches' vacated by 
pterosaurs through normal extinction processes and thus slowly displaced pter!
!
osaurs in an indirect way. However, there is very little direct evidence to 
support this, and in any case I suspect that ecologically specking, while 
pterosaurs may have overlapped with birds to some extent, pterosaur 'niches' 
were probably different from those of birds and the two groups were capable of 
coexistence, perhaps with a little friction at the edges. Climatic conditions 
(strong or gusty winds) have often been cited as potentially lethal for 
pterosaurs, but even giant forms were around for millions of years. Since these 
and other pterosaurs were, undoubtedly, well adapted to the environments in 
which they lived it is likely that only really extreme conditions that spread 
world-wide are likely to have finished off entire species. 

The bottom line is that even with an incredibly dense fossil record (e.g. as 
for microfossils), remarkably good temporal and stratigraphic control and huge 
amounts of data on environmental conditions, and their geographic and historic 
variation, it is well nigh impossible to determine how or why groups such as 
pterosaurs or dinosaurs became extinct. Still, its fun (and stimulating) to 
speculate, and maybe someone will tackle pterosaur extinction at the pterosaur 
meeting to be held in Toulouse in early September. 

Tschuess

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)

web site: http://www.museum.hu-berlin.de/pal/vertp/unwinvp.html 
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