Re: New alvarezsaurid

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

>It is in _Archaeopteryx bavarica_...although it is quite reduced 
(secondarily?
>who knows?), to fit on the small sternum.
>

   I don't know why you can say that a carinate sternum is primitive for 
Aves and Avetheropoda. Clearly volant early birds do not have a carinate 
sternum and neither do dromaeosaurs. 

>Again, since we don't know what the common ancestor of allosaurids and 
birds
>looked like, we can't say whether it had a carinate sternum. If not, 
then the
>keel evolved twice (not a major problem, since it definitely evolved
>independently of birds in pterosaurs).
>

    I agree it is not a major problem if it evolved twice ( actually 
over a dozen odd times among amniotes ), and lets leave it at that.

MattTroutman

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