After two centuries examining pterosaur fossils, scientists have learned much about their anatomy. Let’s look at those featherless wings, what some eyewitnesses (of apparent pterosaurs) compare with bat wings. We’ll begin with fingers, including the one finger that supports the wing:
For pterosaurs, one of the four fingers (digits) supports the wing. The other three are for graspings, similar to digits in other animals. But we need to compare this with the wings and fingers of bats:
Notice the above image and the use of the bat’s five digits: one for a claw and four in support of the wing: far different from the pterosaur’s three-claw/one-support.
Eskin Kuhn sketched the above two long-tailed flying creatures soon after he observed them in Cuba, in 1971. The drawing does not show the claw finger or fingers clearly, but he described the wing-finger structure as follows:
“The structure and the texture of the wings appeared to be very similar to that of bats: particularly in that the struts of the wings emanated from a “hand” as fingers would; except that a couple of the fingers were short (as for grasping) and the other ran out to the tip of the wing, others back to the trailing edge of the wing to stretch the wing membrane as a kite would.”
One skeptic may have noticed part of this description and concluded it correlated with bat anatomy rather than pterosaur anatomy. Concerning the wings, the eyewitness did say “very similar to bats.” Perhaps that skeptic did not read the whole sentence, however. The sketch itself does not show the bat-hands that seem to be described by “emanated from a ‘hand’ as fingers would.” Did Mr. Kuhn really have a detailed knowledge of bat anatomy? It seems to have been only a generalized knowledge, for the next part of his description is anything but bat-like.
. . . a couple of the fingers were short (as for grasping)
Bats do not have two short fingers for grasping, only one. To be sure, pterosaurs have three, but one of those three could easily be hidden during flight, or close enough to another claw-finger that three looked like two.
Consider what he next describes:
. . . others [fingers] back to the trailing edge of the wing to stretch the wing membrane as a kite would . . .
Neither bats nor pterosaurs have any finger or fingers at the trailing edge of the wing membrane. That does not mean that there is never any appearance of any structure at the trailing edge; but I suspect that Kuhn simply misinterpreted it, assuming it was part of the bone structure.
Even for newcomers to pterosaur fossils, the three claw-fingers are easy to distinguish above. The long wing finger, digit number four, however, dwarfs the other three . . .