Re: New alvarezsaurid

[Dinogeorge <Dinogeorge@aol.com>]

In a message dated 98-03-29 17:42:12 EST, m_troutman@hotmail.com writes:

<< The carina is not seen in basal birds such as Archaeopteryx... >>

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

<<...so it is not seen in the common ancestor of allosaurs and birds. >>

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).