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Re: New alvarezsaurid
>It is in _Archaeopteryx bavarica_...although it is quite reduced
>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
>looked like, we can't say whether it had a carinate sternum. If not,
>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.
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