More evidence for a narrow chord wing membrane in pterosaurs

Unidentified by a museum number
this beautifully complete and articulated Solnhofen (Late Jurassic) Rhamphorhynchus specimen (Figs. 1, 2) preserve outlines of soft tissue, including a narrow-chord wing membrane (supporting Zittel 1882; Schaller 1985; Peters 2002; contra Unwin and Bakhurina 1994; Elgin, Hone and Frey 2011).

Figure 1. Rhamphorhynchus specimen preserving soft tissue, including a narrow-chord wing membrane. For details see figure 2.

Figure 1. Rhamphorhynchus specimen preserving soft tissue, including a narrow-chord wing membrane. For details see figure 2.

A closer view reveals a wing-tip ungual
(Fig. 2) better presented when Photoshop increases the contrast in the photo. Note: the other wingtip is more buried. This one less so. You’re still seeing the matrix over the wingtip ungual. The preparators did not excavate the entire wingtip from either wing.

Also worthy of note:
the propatagium extends to the deltopectoral crest, not to the neck. Pedal digit 5 is not connected to the uropatagia or any other membrane. And there is no single deep chord uropatagium extending between the legs. The toes are also webbed in other specimens. Here those webs are covered by the brachiopatagium.

Figure 2. Closer view of the specimen in figure 1 with overlays showing the various membranes and wingtip ungual.

Figure 2. Closer view of the specimen in figure 1 with overlays showing the various membranes and wingtip ungual, here a little bit buried along with the tip of m4.4, probably expanding the apparent size of the wing tip, just as burying an arrowhead necessitates using more mud to cover the edges and smooth out the edges.

As documented
earlier, the deep chord wing membrane is never found in pterosaurs. Both Unwin and Bakhurina 1994 and Elgin, Hone and Frey 2011 used cartoonish outlines to fudge their data. And when Elgin, Hone and Frey 2011 could not fudge their data (e.g. the Zittel wing), their desperation to avoid confirming Peters 2002 forced them to claim ‘membrane shrinkage‘ when there was none. I’m not sugar-coating this. This is what some paleontologists do in the present age. Be ready for it when you enter this field.

Click to animate. This is the Vienna specimen of Pterodactylus, which preserves twin uropatagia behind the knees.

Click to animate. This is the Vienna specimen of Pterodactylus, which preserves twin uropatagia behind the knees.

Is this a case of confirmation bias?
Yes. But I have yet to see any examples that confirm any other interpretation. Please send them if you have them.

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.
Peters D 2009. A reinterpretation of pteroid articulation in pterosaurs. Journal of Vertebrate Paleontology 29:1327-1330.
Prondvai E and Hone DWE 2009. New models for the wing extension in pterosaurs. Historical Biology DOI: 10.1080/08912960902859334
Schaller D 1985. Wing Evolution. In: Hecht, M., Ostrom, J.H., Viohl, G. and Wellnhofer, P., eds, The Beginning of Birds. Proceedings of the International Archaeopteryx Conference, Eichstätt 1984, (Freundes Jura Museum, Eichstätt),pp. 333–348.
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.

http://reptileevolution.com/pterosaur-wings.htm
http://reptileevolution.com/pterosaur-wings2.htm
http://reptileevolution.com/rhamphorhynchus-wings.htm

 

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