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Re: Senter 2006, Confuciusornis, and humeral mobility



On Mar 22, 2011, at 4:53 PM, Jason Brougham wrote:

> At least half of the specimens lack aerodynamic tail feathers, which suggests 
> that any aerodynamic capabilities would be unstable, advanced, types rather 
> than gliding which would probably benefit from  a good stabilizer (like the 
> long tail of Archaeopteryx).

Just as a quick note, it is a myth that the tail of modern birds is primarily a 
stabilizer; it is also a myth that unpowered flight must be more stable than 
powered flight.  The long tail of Archaeopteryx would tend to act as a passive 
stabilizer because of the specific effects on the drag profile it would tend to 
promote.  It has been suggested that taxa near the base of a group that later 
develops powered flight might benefit from passive stabilization, as those 
organisms might lack the required neural architecture to control unstable 
flight.  To the extent that those stem-taxa might be unpowered, then basal 
gliders could be expected to be more stable than more derived members of the 
group (seems to be true for birds).  I don't mean to suggest that you, 
personally, were mistaken but only that the terminology regarding stabilization 
and gliding is often taken to mean something it does not (in both casual 
conversation and in published works, sadly).

--Mike H.


> 
> 

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