Re: New alvarezsaurid

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

>
>I haven't said that the maniraptoran hand makes for a better flier. I 
only
>said that the maniraptoran hand is found in all avians and in many 
pre-avian
>dino-birds. I've decided to refrain from making statements about 
whether
>anatomical features are "better" for this or "better" for that purpose, 
since
>such statements cannot presently be substantiated. All we can do is 
catalogue
>the existence or nonexistence of these features in the specimens we 
have.

    Very well put.

>I can speculate, however, that because the less mobile, longer hand 
exists in
>so many extant flying avians, whereas the more mobile, grasping hand of
>earlier theropods does not, that the less mobile hand was an adaptation 
for
>flight within the theropod clade--for reasons presently unknowable, at 
least
>until someone actually performs wind-tunnel studies (real or 
computer-virtual)
>on various accurately modeled theropod hands and compares their 
aerodynamic
>characteristics.

    It can also have evolved for climbing.

>Who knows? Perhaps the less mobile hand evolved to help the 
ur-maniraptoran to
>scratch itself and preen better, and then all its descendants became 
stuck
>with this kind of hand to use as a wing, even though the looser, 
shorter hand
>would have made a "better" wing. If you think this is a ridiculous 
idea, show
>me why.
>

    I don't think that the 'preening' model makes sense. Hoatzin chicks, 
with their stiff mani and seperate fingers do not preen themselves with 
them. Preening is important for birds ( well, at least in my bird ). 

The best, present interpretation is that it evolved for climbing.

MattTroutman

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