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RE: Secondarily Flightless Question



Jaime Headden wrote:

>  Only tinamous today among ratites fly, but comparison to the fossil 
>record shows that primitively, ratites lost flight perhaps several 
> times. 

Perhaps feeble flight ability is actually primitive for the Neornithes.
Tinamous (on the Palaeognathae side) and screamers (close to the base of the
Neognathae) are both poor fliers.  The basal lineages of neornithine birds
were therefore more predisposed to losing this ability completely... not
just ratites, but maybe dromornithids (anseriform kin) too.  The more
accomplished flight abilities of most modern birds would therefore be
derived.

Ronald Orenstein wrote:

> Even in modern birds there has been argument about the flying ability 
> of some species (eg the Kagu of New Caledonia), 

Good point.  The kagu has been reported to capable of short gliding
descents.  It therefore uses its wings for aerial locomotion, but not
flight.

Tracy Ford wrote:
  
> Really? I find it right on the money. Other than myself, George, Greg, 
> Sankar, what other paleontologist believe theropods could climb? 

There was also that fellow O.C. Marsh... oh, maybe 200 year ago.  :-)

To be fair, I think the scientific community can be forgiven for being very
cautious with regards to the issue of tree-climbing non-avian theropods in
the past.  Until very recently, there was no direct anatomical evidence for
scansorial behavior in this group.  Now we have the luxury of a raft of
small theropods that show scansorial specializations.  But those of us who
advocated climbing behavior in theropods must be honest and admit that,
before these discoveries, we were stretching the (then) available evidence
to breaking point.  _Microraptor_ and _Scansoriopteryx_ have considerably
lightened the burden.




Tim