Re: Pterosaur wing membranes

[Michael Habib <mhabib5@jhmi.edu>]

> The cropped photo is a bit like quoting a sentence out of context.  
> What structure causes the continuation of the brown coloration that 
> extends undisturbed on out past the other side of the leg?  Is is 
> possible that this is a coincidental artifact of positioning, perhaps 
> of a wingtip or some other feature?  I sure would like to see more of 
> the photo


The photo also has the same problem that many of the pterosaur 
specimens do, which is it doesn't actually demonstrate that the 
patagium seen attaching to the ankle is the trailing edge of the 
brachiopatagium.  It is quite possible that the patagium seen running 
to the ankle is coming from the hip region (ie.  it is a hindlimb 
patagium separate from the main wing).  This interpretation is also 
quite consistent with the membrane impressions present in many of the 
other supposed 'broad wing' pterosaur specimens.  Note that this is not 
my idea; Jim Cunningham and John Conway beat me to the punch on that 
one (and it may have been proposed by someone before them as well, I 
cannot say).

And, of course, there is the possibility that the brachiopatagium did 
run to the hindlimb, but only as a very narrow stretch of membrane 
(thus maintaining an overall narrow chord).  While the separate 
membranes makes more sense to me, the narrow 'fillet' model at least 
maintains a narrow chord, which makes infinitely more sense than the 
broad chord model from a flight dynamics standpoint.


Cheers,

--Mike Habib