Bennett (2007) reported that Anurognathus only had three wing phalanges. Not true, as the image of the fossil below demonstrates. Granted, the distal wing phalanges are hard to see, but once again, succeeding sister taxa all have four.
Anurognathus would have been an agile aerial insectivore, able to trap insects on the wing with its gaping jaws.
The wings did not attach to the ankles (contra Elgin, Hone and Frey in press), nor did they come to impossibly narrow points distally. This wingshape, presented in Peters (2001), evolved from the wing of Longisquama, Cosesaurus and Sharovipteryx, distally to produce thrust, not proximally as gliding membranes, as imagined by Bennett (2008) and others before him. Aktinofibrils spread like a Japanese fan to provide the shape and support the wings needed to fly, and permitted them to fold up and virtually disappear when not flying. Any sort of wing model that extends the trailing edges to the ankles always leaves a wrinkled blanket when folded. Not good. And there's no set of taxa in the Repilia that demonstrate how such a wing could have evolved.
Also notice what the hind limbs are doing. Along with the uropatagium they create horizontal stabilizers, like on airplanes.
The feet, webbed as they were, acted like twin rudders. They also created aerodynamic lift laterally in order to help keep the legs outstretched.
Finally, note how broad the thighs were, matching the length of the pelvis. With such thighs, pterosaurs were powerful runners on the ground, wings folded. Such thighs are only otherwise found in dinosaurs (including birds) and mammals, both of which are warm-blooded clades. |
