The Insights of Dietrich Schaller

Figure 1. Zittel's (1882) interpretation of the Zittel wing , narrow to the elbow (the body was added).

Beyond all reason, the shape of pterosaur wings and their connection to the hind limb form continuing arguments.

Zittel 1882
Karl von Zittel (1882) provided early insight with the discovery of a perfectly preserved Rhamphorhynchus wing and his precise interpretation of it  (Fig. 1) – narrow to the elbow. The negligible extension to the left knee (rather than mid-thigh, as shown on the right wing) is forgivable).

Schaller 1983
One hundred years later, the next scientist who understood that Zittel (1882) was correct, was Dietrich Schaller (1983, 1985, 2007) who carefully studied and interpreted the materials, but was largely ignored by the vast majority of pterosaur workers.

Interpretations of pterosaur wings by Dietrch Schaller (2007).

Figure 2. Interpretations of pterosaur wings by Dietrch Schaller (2007).

Insights
Schaller (2007) studied and illustrated (Fig. 2) several pterosaur specimens with well-preserved wing membranes and found a remarkable consistency in their shape. All were stretched between the wingtip and elbow and consisted of various zones, which he color-coded. None overextended the elbow. All demonstrate a slight spoon shape at the tip. Schaller (2007) illustrated uropatagia stretched between the tail and hind limb, rather than between the hind limbs as others illustrated it based on the false interpretations of Sharov (1971) and Unwin and Bakhurina (1994). Schaller (2007) also illustrated the hind limb fully and laterally extended, as in Sharovipteryx. This provided a horizontal stabilizer, as in modern airplanes, that would have provided sufficient lift to the hind limbs to keep them laterally extended without effort.

Vienna specimen of Pterodactylus.

Figure 3. The Vienna specimen of Pterodactylus in situ from Elgin, Hone and Frey 2011. Click to see the specimen.

Oversights
Following established (but false) paradigms, Schaller (2007) illustrated the uropatagium (in orange, Fig. 2) extending to the tip of the fifth toe, but there is no evidence of this. The uropatagium extended only to the ankle. The fifth toe was hinged and extremely thin. It would not have made a good uropatagium stretcher.

Schaller (2007) illustrated the fuselage fillet (“plagiopatagium” in royal blue) oriented toward the knee, rather than mid thigh with a very thin anterior extension to the ankle. Such an extension would not have been aerodynamically desirable, but reflects a remnant of the paradigm of the deep chord hypothesis. Strangely, Schaller (2007, Fig. 2) did not illustrate the fuselage fillet in Rhamphorhynchus and Pterodactylus, where it is most clearly preserved (Fig. 3).

Even so
Others have ignored his work, but Schaller deserves credit (as I gave him in Peters 2002) for keeping the valid Zittel wing shape hypothesis alive. Early work (Schaller 1985) interpreting Sordes was marred (he gave it a flying squirrel-like wing membrane), but corrected in Schaller (2007, Fig. 2) and for this he also deserves credit.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
Elgin RA, Hone DWE and Frey E 2011. The extent of the pterosaur flight membrane. Acta Palaeontologica Polonica 56 (1), 2011: 99-111. doi: 10.4202/app.2009.0145
Peters D 2002. A New Model for the Evolution of the Pterosaur Wing – with a twist. – Historical Biology 15: 277–301.
Schaller D 1983.
Nuebeschreibung des Pterosaurierflügels. Zoologisches Institut der Universitätt München.
Schaller D 1985. Wing Evolution. In: Hecht M, Ostrom JH, Viohl G and Wellnhofer P eds. The Beginning of Birds. Proceedings of the International Archaeopteryx Conference, Eichstätt 1984, (Freundes Jura Museum, Eichstätt), 333–348.
Schaller D 2007. The superordinate Pterosaur Evolution as deduced from the Evolution of their Wings. On the occasion of The Wellnhofer Pterosaur Meeting, Munich 2007, Verlag Dr. Friedrich Pfeil, Munchen. on sale
Sharov AG 1971. New flying reptiles fro the Mesozoic of Kazakhstan and Kirghizia. Trudy of the Paleontological Institute, Akademia Nauk, USSR, Moscow, 130: 104–113 [in Russian].
Unwin DM and Bakhurina NN 1994. Sordes pilosus and the nature of the pterosaur flight apparatus. Nature 371: 62-64.
Zittel KA 1882. Über Flugsaurier aus dem lithographischen Schiefer Bayerns. Palaeontographica 29: 7-80.

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