Re: semilunate carpal

["Tim Williams" <twilliams_alpha@hotmail.com>]

Patrick Norton wrote:

> >(2) Aerial locomotion: The "swivel wrist" was evolved for orientational
> control (steering and stability) during aerial descents.<
>
> Tim, that is not at all what I'm saying. I'm talking only about evolution 
> of aerodynamic orientational control in cursorial animals.

Then I apologize for the misinterpretion.  Orientational control during 
aerial "ascents".


> >(2) holds that secondarily non-aerolocomotive<
>
> Aarrghhhhhhhhhh! One more time, I am NOT talking about a secondarily 
> flightless >condition!

Nor am I.  By aerial locomotion I mean any process by which the properties 
of air are used in some locomotory capacity - to assist in running, turning, 
leaping, flying, etc.  In arguing that the "predatory stroke" was exapted 
from an aerial steering device, it is secondarily non-aerolocomotive.

> My premise is that the avian folding wrist evolved in cursors as an 
> advancement for aerodymanic control when moving quickly >on the ground<.  
> Please stop restating my position if you insist on getting it wrong.

See above.

As I understand it, a model quite similar to yours was proposed in 1985 by 
Peterson (I may have the spelling wrong - I'm going from memory here).  This 
model was itself a modification of the flapping-start cursorial model 
proposed by Caple et al. (1983).


Tim


---------------------------------------------------------------------

Timothy J. Williams

USDA-ARS Researcher
Agronomy Hall
Iowa State University
Ames IA 50014

Phone: 515 294 9233
Fax:   515 294 3163




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