Re: New alvarezsaurid

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

><< Theropods, and 
> espcially the "flightless" ones still have mobile wrists which are 
> incongruent with forelimb function as " prey holders ".  >>
>
>Of course they had mobile wrists, because the wings of their ancestral 
forms
>retained considerable grasping ability. Having a mobile wrist (and even 
an
>opposable manual digit I) is not at all incongruous with "prey 
holding"! The
>ancestral forms were nowhere near as highly adapted fliers as are 
modern
>birds, so their flightless cursorial descendants retained considerably 
more of
>the non-flying forelimb functions than did, for example, flightless
>maniraptorans or more modern flightless forms.
>

  Flying requieres considerable control over the movements of the manus 
in birds. All birds, basal and derived, had more control over the 
movements of the manus. Larry Martin has shown that even Archaeopteryx 
had a heart-shaped ulnarae. All enantiornithines had heart-shaped 
ulnarae. The only thing that really makes the basal bird manus more " 
primitive " is that the fingers were more mobile. Regardless, a mobile 
manus is not a predatory design. A manus where the phalanges are 
parallel to the radioulna is better for "prey handling" because it 
resists strain and is inheritantly more stable. 

MattTroutman

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