Pterosaur and bat wing origins

It has been a long time
since some aspect of pterosaur biology was covered here, what with theropods, turtles and lizards stealing the spotlight lately. It is also remarkable that the origin of bats continues to be the hottest topic (by far) at the PterosaurHeresies day-after-day. Let’s take a look at both today and see what we can learn.

Figure 1. Bat embryo wing shape compared to Pterodactylus. Note the ability to fold (relax) the wings until they virtually disappear in both cases. Also note the origin of bat wings paralleling those of pterosaur wings in that during embryology the bat wing also has a narrow chord that more deeply develops long after birth.

Figure 1. Bat embryo wing shape compared to Pterodactylus. Note the ability to fold (relax) the wings until they virtually disappear in both cases. Also note the origin of bat wings paralleling those of pterosaur wings in that during embryology the bat wing also has a narrow chord. Distinct from pterosaur wings the bat wing more deeply develops long after birth. Last minute note: bat hind limbs sprawl, unlike most mammals, but like Pterodactylus hind limbs (but not Dimorphodon and kin, they had erect hind limbs). 

Bat wings
According to the evidence shown above in the embryo bat, the fingers and the wing membrane do not achieve adult proportions until long after birth. Babies cling to their mothers. The wing membrane of the embryo converges with that of pterosaur in having a very shallow at the elbow wing chord, but it diverges during ontogeny because it deepens with maturation. The Myotis embryo lacks uropatagia. That, too, develops later in the process (see above) and reaches its fullest extent long after birth. Adult image here.

A casual look around the Internet 
shows that the deep chord wing membrane model of pterosaurs promoted by Hone, Elgin, Bennett and Witton have been widely adopted. And that’s akin to hogwash and alchemy, not Science. In Science you don’t make up excuses (like membrane shrinking) to match preconceptions. You observe reality. Facts are facts. No one has yet produced a pterosaur specimen with a deep chord wing membrane. By contrast, all available examples (like Figs. 2, 4) demonstrate the opposite.

Figure 2. Here is the Vienna specimen of Pterodactylus in situ and with matrix removed. Now compare this figure with figure 3, which shows the wings and uropatagia unfolding. There is no way to turn this into a deep chord wing membrane. And it decouples the forelimbs from the hind limbs.

Figure 2. Here is the Vienna specimen of Pterodactylus in situ and with matrix removed. Now compare this figure with figure 3, which shows the wings and uropatagia unfolding. There is no way to turn this into a deep chord wing membrane. And it decouples the forelimbs from the hind limbs. Why don’t other pterosaur workers accept this. Because they are too deeply married to the false paradigm.

Now
let’s unfold those Pterodactylus wings (Fig. 3)

The Vienna Pterodactylus.

Figure 3. The Vienna Pterodactylus. Click to animate. Wing membranes in situ (when folded) then animated to extend them. There is no shrinkage here or in ANY pterosaur wing membrane. There is only an “explanation” to avoid dealing with the hard evidence here and elsewhere that the pterosaur wing was stretched between the elbow and wing tip. Any other explanation is alchemy and hogwash.

You may remember that the deep chord/single uropatagium theory
goes back to Sharov (1971) who vaguely traced wing membranes as they appeared on Sordes without regard for taphonomy. Click here for more details on Sordes.

The myth of the pterosaur uropatagium

Fig. 4. The Sordes uropatagium is actually displaced wing material carried between the ankles by the displaced radius and ulna.

And the origin of the pterosaur wing
of course, goes back to the nonviolent Cosesaurus, which had trailing fibers from the forelimb first noticed by Ellenberger 1993 and Peters 2009 and also here and here.

References
Ellenberger P 1993. Cosesaurus aviceps . Vertébré aviforme du Trias Moyen de Catalogne. Étude descriptive et comparative. Mémoire Avec le concours de l’École Pratique des Hautes Etudes. Laboratorie de Paléontologie des Vertébrés. Univ. Sci. Tech. Languedoc, Montpellier (France). Pp. 1-664.
Peters D 2009. A reinterpretation of pteroid articulation in pterosaurs. Journal of Vertebrate Paleontology 29: 1327-1330
Sharov AG 1971. 
New flying reptiles from the Mesozoic of Kazakhstan and Kirghizia. – Transactions of the Paleontological Institute, Akademia Nauk, USSR, Moscow, 130: 104–113 [in Russian].

 

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