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RE: smallest ANCIENT non-bird dinosaur - was what I was asking


Jamie Stearns wrote:


> I wonder if Aves ought to be defined as Passer>Velociraptor from now on.


This is effectively the definition of Avialae proposed by some.


> Granted, this could place certain dromaeosaur taxa within _Aves_, but I'd
> say there's somewhat more stability with this definition then arbitrarily
> anchoring the clade on Archaeopteryx, whose position has become somewhat
> problematic as of late. 


Yes, Mike implied this too regarding _Archaeopteryx_.  The only "problematic" 
aspect I can see comes from the phylogeny of Mayr et al. (2005) [the "Tenth 
specimen of _Archaeopteryx_" paper], which has an _Archaeopteryx_-_Rahonavis_ 
as sister group to a Deinonychosauria clade that included _Confuciusornis_ (!). 
 However, I think it was agreed at the time that the analysis could have 
benefited from the inclusion of a better representation of avian ("bird") taxa. 


But, if an analysis *did* show that _Archaeopteryx_ was basal to a 
Deinonychosauria+Ornithurae clade, then deinonychosaurs would be inside Aves 
(if the definition of Aves is anchored in _Archaeopteryx_, without any external 
specifiers).  This would mean that _Velociraptor_ would be an "avian" - and we 
would be perfectly justified in calling it a "secondarily flightless bird".  
IMHO, what's the big deal?  _Mononykus_ was originally regarded as a 
secondarily flightless bird, before being removed to outside Avialae/Aves.  Why 
couldn't certain non-traditional avians (like _Velociraptor_) be moved in the 
other direction?  If deinonychosaurs did evolve from flighted theropods, and 
are closer to modern birds than _Archaeopteryx_ is, then they deserve to be put 
in Aves - and be called "birds".  


Cheers

Tim
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