Re: Nice example of narrow chord pterosaur wing on the 'net

[Mike Habib <habib@jhmi.edu>]

On Mar 21, 2010, at 6:44 AM, David Peters wrote:

> 1. There is a beginning and and an end to the inboard wing membrane  
> CM 11 426. The  part that is missing crosses the ventral rim of the  
> torso. The edges at the end of the beginning and the beginning of  
> the end point directly toward each other.

Sure, they point at each other.  That doesn't mean they point in the  
direction that the membrane took in life.  Furthermore, the approach  
the body or limb may not have been at a constant angle/arc.  In fact,  
it is quite likely that it didn't for structural and aerodynamic  
reasons.  If you were to apply the same reasoning that you use above  
to modern bats, you would end up estimating a hip attachment for the  
inboard patagia for many species, because the wing inboard of the  
elbow takes the path of an arc, rather than a straight line.


> There are two models of pterosaur wing membrane attachment out  
> there, the one that attaches to mid thigh and all the others. This  
> specimen supports the former.

[Insert look of utter confusion] - there are at least four wing  
membrane attachment models in the literature, arguably five if you  
include variants of the ankle attachment.  There are several other  
plausible ones that aren't even in the literature.  So we're looking  
at something like four to seven plausible membrane models.


> 2. I don't simply "dismiss" the other wing shapes. A paper was  
> published that demonstrated how those wing shapes were based on  
> misidentiications.

You published a paper in which you *argued* for misidentifications.  I  
think you had some good arguments there - but that's not a "slam  
dunk", especially when we're talking about specimens that others have  
seen personally but we are examining in photos (in the case of the CM  
specimen, I've actually looked at it personally).


> No paper in the last eight years has put forth evidence to the  
> contrary. Were there evidence to the contrary those who support the  
> other side would have published (witness Hone & Benton 2007, 2008;  
> Hone et al. 2009). Such a paper is heartily encouraged as it is  
> better to figure this out in complete detail.

Well, there are: Wang et al. 2002; Lü 2002; Bakhurina and Unwin 2003;  
Frey et al. 2003 and Bennett 2007.  That's a fair number in the last  
eight years.  There hasn't been as much debate over it as there once  
was, largely because there is wide agreement for a generally narrow  
chord wing, with most of the lasting disagreement centered around  
inboard attachment.  Since the attachment, itself, has less overall  
functional effect than the general shape of the wing as a whole, many  
researchers have calmed down a bit on the debate.

Cheers,

--Mike


Michael Habib
Assistant Professor of Biology
Chatham University
Woodland Road, Pittsburgh PA  15232
Buhl Hall, Room 226A
mhabib@chatham.edu
(443) 280-0181