Re: pteros have lift-off

[Tim Williams <tijawi@yahoo.com>]

Augusto Haro wrote:


> > Elongation of the forelimbs is a character that
> appears to be primitive for coelurosaurs.
> 
> but not to the degree of Archaeopteryx, I suppose...


True.  But context is important here, which was (to quote D. Peters): 
"Archaeopteryx and other birdy descendants of short-armed theropods".  
Whichever ancestral group DP had in mind (= basal eumaniraptorans, basal 
maniraptorans, or basal coelurosaurs), I wouldn't characterize any of these as 
"short-armed".  I'd be surprised if GSP did either.  

Forelimb (especially manus) elongation by birds was not a revolutionary change. 
 It was a further extension of the ancestral "long-armed" condition of 
coelurosaurs.  Therizinosaurs also show increased forelimb elongation, but for 
very different reasons to birds (presumably).



Cheers

Tim