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



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