Re: MY THOUGHTS ON THE 'DINO/BIRDS'

["Matthew Troutman" <m_troutman@hotmail.com>]

<<I find this highly unlikely, and I am not sure on what you base it.  
Surely Caudipteryx at least, with its long legs and shortened forearms 
(at least compared to Protarchaeopteryx) seems a most unlikely glider. I 
would have thought the most obvious use for the tail fan at least was 
display, though as I suggested in an earlier post I can imagine (based 
on no analysis whatever) it making short, fluttering leaps - again, 
perhaps, in display.>>

You may be right with Caudipteryx, its tail is rather similiar to the 
some of the fan tails found in colies and some "piciformes" (and 
Sandcoleiformes) that might be for display.  However, nothing says that 
the tail didn't bear a slight aerodynamic function perhaps related to 
arboreality.  

I still cannot find any logic within the "fluttering" model that was 
made by Caple et al.. I go along with Rayner (1991) who says: 

"...are implausible, for two reasons.  First, there are no comtemporary 
analogues of running animals feeding with their wings, or using 
forelimbs as lifting surfaces for stability: running birds generally 
fold their wings to minimize drag.  Second, and more important, neither 
model addresses the question of *why* the wings should be flapped, and 
how imprecise forms of wing waving needed for predation or stability 
developed into true flapping... the main pressure for this model has 
come form unfounded objections to the gliding model, often arising from 
misunderstanding of flapping flight mechanics (as in Balda, Caple & 
Willis 1985).  The fluttering model must fail because it takes no 
account of the extreme morphological, physiological and behavioural 
specializations required for flight.  Slow flight, take-off and landing 
are the most demanding types of flight experienced by most birds, and 
yet the first "flights" of a fluttering proto-flapper would have been at 
low speeds, where the energetic demands of flight are at their most 
extreme (Clark 1977), and the wingbeat cycle is at its most complex 
(Rayner 1988a,b).  This model need not be considered further."

Rayner thought that the gliding, arboreal was the best model put out 
because of the easy use of the gravity and the easy steps needed to 
evolve flight.  The only reason he doesn't support it is the problem of 
theropods and Archaeopteryx and their cursoriality.  This is why he 
supported the hypothesis that flight in birds evolved when theropods ran 
and jumped into the wind.  This fails because it assumes that wind would 
be constant and that early birds did not the have the special anatomical 
controls that modern birds had.  

Rayner didn't take into the account that some theropods were arboreal 
and if some were proven to be arboreal, I'm sure Rayner would go to the 
arboreal theory.  

<<This highlights one of the bugbears I have argued about repeatedly 
here - the assumption that gliding is THE intermediate stage between 
full powered flight and flightlessness.>>

I didn't sat this.  

Matt Troutman

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