Re: Dinosaur Taxonomy (was Re: Re: dinosaur flatware)

[Stan Friesen <swf@ElSegundoCA.ATTGIS.COM>]

From: pharrinj@PLU.edu
 > On Mon, 15 Jan 1996, Stan Friesen wrote:
 > > 
 > > Not if the defining characters of Herrerasauria do not include any
 > > uniquely derived characters found only in the known herrerasaurs.
 > 
 > If that is the case, then no taxon Herrerasauria should ever be 
 > diagnosed, and the points discussed here become moot.

Yes it can - it just is diagnosed on a combination of theropod
apomorphies and the plesiomorphic condition of the characters used
to diagnose the "higher" theropods.  This is *always* how one
diagnoses a paraphyletic taxon!!  It is still a "differntial
diagnosis", as it still specifies how the taxon differs from all
coordinate taxa.

It is only cladists that insist on restricting a diagnosis to
apomorphic characters only!


[By the way, I can prove that, unless one uses the "cladistic species
definition", the Rules of Zoological Nomenclature *require* the existance
of at least *some* paraphyletic genera].

swf@elsegundoca.attgis.com              sarima@netcom.com

The peace of God be with you.