Re: Quick question for pterosaur aficionados:

[Mike Habib <habib@jhmi.edu>]

I guess you could say phylogeny?  Flying animals, as a general rule,  
flex whatever joints are available to reshape the wing as needed (be  
it span reduction during flight or folding of the wing "on the  
tarmac").  For bats, a lot of the motion comes from the digits, while  
birds have fused digits and therefore rely heavily on wrist flexion,  
instead (especially for wing folding when not in flight).  Pterosaurs  
don't have any joints fused up in the forelimb, so they're all able to  
flex to some degree for purposes of folding and span reduction.   
However, the MC-PH joint of the fourth digit is the most mobile in  
this regard, and probably did most of the folding.  Elbow and shoulder  
also certainly important, along with the wrist, especially for span  
reduction in flight.

If they have it, they can use it.

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



On Mar 24, 2010, at 12:29 PM, David Peters wrote:

> I was more interested in complete folding, like "on the tarmac."
> But thanks for that data.
>
> Some of both? Is this phylogenetic? Or happenstance?
>
> David Peters
> davidpeters@att.net
>
>
> > Some of both.  Any joints that
> > can be flexed will help fold the wing.  Most of this
> > will occur at MCIV-PhIV (outboard), but the elbow can flex,
> > as can the wrist.  For actual folding, the wing finger
> > is most important, but it should be noted that span
> > reduction during flight was likely accomplished more at the
> > elbow and wrist.  The initial span reduction produces
> > extra cambering, and so (counter-intuitively) increases the
> > lift on the span-reduced wing.  Additional span
> > reduction reduces lift as area shrinks, and then reduces it
> > a great deal if the wing begins to flutter (this last issue
> > prevented pterosaurs from utilizing the same degree of span
> > reduction in flight as birds use).
> >
> > --Mike
> >
> >
> > Michael Habib
> > Assistant Professor of Biology
> > Chatham University
> > Woodland Road, Pittsburgh PA  15232
> > Buhl Hall, Room 226A
> > mhabib@chatham.edu
> > (443) 280-0181
> >
> >
> >
> > On Mar 23, 2010, at 9:33 PM, David Peters wrote:
> >
> > > Wing folding:
> > >
> > > Inboard or outboard of the elbow?
> > >
> > > You can probably guess what I would say, but I'll
> > weigh in after others have spoken.
> > > David Peters
> > > St. Louis