RE: New dinobird "Sinovenator"

["Williams, Tim" <TiJaWi@agron.iastate.edu>]

David Marjanovic wrote:

>Just to make sure -- "derived" doesn't mean "closer to Neornithes", it
>means having a longer branch (having evolved further away from some >common
ancestor).

...such as indicated by the accumulation of apomorphies.

The skeleton of _Archaeopteryx_ is actually one of the most conservative and
least specialized of all maniraptorans.  Identifying autapomorphies in the
skeleton of _Archaeopteryx_ has actually proven to be very challenging (and
may simply be because they're just not there).  The integument of
_Archaeopteryx_ appears to be a totally different matter - although here the
frame of reference is much narrower, since comparatively few Mesozoic
maniraptorans have integument preserved along with the skeleton.

Just because a species is "closer to Neornithes" DOES NOT automatically mean
that it is "more derived" (or "more advanced)".  This assumption goes
hand-in-hand with the outmoded notion that birds should get their own
"Class" because the darn things can flap and fly.  

That's enough from me.

Tim


------------------------------------------------------------ 

Timothy J. Williams 

USDA-ARS Researcher 
Agronomy Hall 
Iowa State University 
Ames IA 50014 

Phone: 515 294 9233 
Fax:   515 294 3163