Re: New alvarezsaurid

[Dinogeorge <Dinogeorge@aol.com>]

In a message dated 98-03-27 04:51:02 EST, jaemei@hotmail.com writes:

<<  If *Allosaurus* possessed a 
 carina or keel, that means the keel did not evolve for flight, at least 
 in this dinosaur (just imagine, an allosaur flapping its stubby little 
 arms {in comparison to the body} as it runs, trying to get lift, jogging 
 towards that cliff over there....). In birds, the keel develops the 
 forward-and-down stroke of the humerus (and hence, the wing) the more 
 powerful movement of the arm in general. The keel increases the normal 
 flexion of the muscles attached, and thus add power to the stroke that 
 existed before birds got wings. Birds just modified it for flight (that, 
 or theropods modified it for...). >>

Now suppose that the keel >did< evolve for flight, in a small, volant
theropod, and was retained by at least one of the descendant lineages of this
small theropod--the lineage that led to the allosaurids. Then we don't have to
imagine an allosaurid trying to take off using its arms in order to account
for the presence of a keel on its sternum. (The keel is not particularly well
developed--it's about as prominent as the keel on the sternum of _Mononykus_.
And we all know what the keel means in _Mononykus_, right?)