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The amazing 'Dark-Wing' Rhamphorhynchus
An excellent description with full colour plates of this incredibly well
preserved Solnhofen pterosaur has just been published in the latest edition of
Archaeopteryx. The full reference is:
Tischlinger, H. and Frey, E. 2002. Ein Rhamphorhynchus (Pterosauria, Reptilia)
mit ungewöhnlicher Flughauterhaltung aus dem Solnhofener Plattenkalk.
Archaeopteryx, 20, 1-20.
I fully agree with the authors that this specimen (JME SOS 4785), which I was
fortunate enough to be able to examine a couple of years ago, is the best
preserved example of Rhamphorhynchus muensteri yet known. The skeleton,
superbly prepared by Dieter Kümpel, is largely uncrushed and associated with
astonishingly well preserved wing membranes that appear to be more complete
than in any other example of this species. Further details of the wing
membranes were revealed using long wavelength UV light. This technique is
discussed in detail by the authors, and again by Tischlinger in a second paper
(this time on Archaeopteryx) in the same volume (note this second paper also
shows some UV light photos of the holotype of Scaphognathus).
The critical new discovery, described by the authors, is of a network of fibres
(probably muscles but might be elastic fibres), that run transverse to the
aktinofibrils (also superbly picked out by the UV light technique). The point
being that such a system is exactly what would be expected (and needed) in an
extensible membrane stretched between the fore and hind limbs. The authors also
describe a blood vessel system that ramifies through the wing-membrane and,
using Tischlingers UV light techniques, were also able to find evidence for
this system in some previously described specimens of Rhamphorhynchus. This is
one of the most significant papers ever published on pterosaurs and I take my
hat off to Tischlinger and Frey for a major ground-breaking contribution.
This specimen also bears directly on previous discussions regarding the
attachment of the brachiopatagium to the hind limb in pterosaurs. Plates 2 and
5 of the Tischlinger and Frey paper clearly show the inner part of the
brachiopatagium extending down the external margin of the tibia as far as the
ankle. This segment of the brachiopatagium has the same colour and texture as
the main part of the brachiopatagium, is completely continuous with it and,
most tellingly, even contains a small fold that starts in the main part of the
brachiopatagium and runs down into the segment of the brachiopatagium external
to the leg. A uropatagium is also preserved, but seems to be narrower than, for
example, in Sordes.
The brachiopatagium of JME SOS 4785 also shows a good match with the
brachiopatagia of other specimens such as the Zittel wing, but emphasises the
incompleteness of the proximal region of the brachiopatagium (either because it
was not preserved or was prepared away) in these examples.
So, as Tischlinger and Frey show in the final figure of their paper,
Rhamphorhynchus has the same basic wing construction as Sordes (no surprises
there then), but exhibits some subtle differences in wing shape that reflect
both differing skeletal proportions and differences in the shape of the
individual flight surfaces. Presumably these, in turn, reflect differing flight
(and life) styles, as hinted at, for example, by the dentition and details of
the hands and feet.
David M. Unwin PhD
Institut fur Palaontologie, MUSEUM FUR NATURKUNDE
Zentralinstitut der Humboldt-Universitat zu Berlin
Invalidenstrasse 43, D-10115 Berlin, GERMANY
0049 30 2093 8577 (office)
0049 30 2093 8862 (department secretary)
0049 30 2093 8868 (fax)