wing extensor placement on pterosaurs

[David Peters <davidrpeters@earthlink.net>]

Funny things happen when you just look at the acme of the Pterosauria  
(Quetz. Ornitho. Pterano.). Let's go back, back, back in time-ime-ime  
to basal forms.

Wellnhofer 1991:54 demonstrates how a Rhamphorhynchus wing opens and  
closes. With wing deployed, the big extensor process of the first  
phalanx is dorsal to digits I-III. I found the same to be true of  
Eudimorphodon. Hence, I-III were ventral to the extensor of the wing.  
Now, if this changes in later pterosaurs with a longer metacarpus, it  
has to be explained. I'm ready to listen.

I see in the reconstruction of the giant Q. that the metacarpals I- 
III, both distally and proximally, are pasted onto the front of the  
wing metacarpal, but on the lower half. Not sure how much of this is  
preserved vs. restored.

Send pictures of your favorite metacarpals!

David Peters
St. Louis

PS. The same illustration (Wellnhofer 1991:54) gives me the willies.  
I thought this was just artistic license, but here the unguals are  
all rotated to face anteriorly, opposite of the wing finger. one  
behind the other, like riding a bicycle built for three. Who is  
onboard with this? And who says the claws should be oriented  
ventrally in flight, as in other tetrapods? Clue me in.