RE: small dinosaurs with feathers

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

"Jura" wrote:

> With very few exceptions, most of the scenarios I have seen where birds
> are referred to as theropods/dinosaurs, have always been for political
> reasons only. 

With all due respect, this assertion is plain nonsense.  Stephan Pickering
is perfectly correct on one point: in a phylogenetic context, birds
represent a monophyletic subset of theropod dinosaurs, and therefore birds
*are* dinosaurs.  Just as mammals are a subset of cynodont therapsids, and
insects are a subset of uniramian arthropods.  I could go on, but we all
have better things to do than rake over these particular coals.

Stephan's extension of this point was that 'bird' should therefore cease to
be used in any scientific sense and remain solely in the vernacular realm,
which others on the list (myself included) took issue with.  The term 'bird'
can be used perfectly well in both a scientific (in this case, phylogenetic)
and vernacular context.


> That is to say, birds are referred to as living dinosaurs/branches of 
> theropoda only when one wants to impress others with the "fact" that 
> dinosaurs didn't all die out 65 mya. 

All of the available evidence, as assessed by phylogenetic analyses, shows
that birds (Aves) evolved from within the Theropoda.  Therefore, birds are
theropods as well as dinosaurs.  Just as mammals are both cynodonts and
therapsids, and insects are both uniramians and arthropods... etc etc etc
etc.



Tim