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RE: Ceratosauria vs. Neotheropoda?



Tim Williams wrote-

> However, in the wrong hands, paraphyletic groupings could spell big trouble. 
> For example, I can foresee the BANDits resurrecting the Thecodontia as a 
> paraphyletic group that includes the (alleged) ancestors of birds, and 
> claiming the validity of Thecodontia is justified under the rules of 
> phylogenetic taxonomy.
>
>
> I know Thecodontia is an extreme example; but I can see paraphyletic groups 
> being misused and abused by people who (whether by accident or design) equate 
> evolutionary 'grades' with clades, and come up with all sorts of spurious 
> phylogenetic hypotheses and conclusions as a result.
 
I'm no fan of BANDits and paraphyletic groups, but I don't see the big worry 
here.  If they define Thecodontia paraphyletically, it will still indicate a 
limited range of taxa that can be used to test phylogenetic hypotheses.  The 
hypothesis Aves is a clade in Archosauriformes that is outside Crocodylomorpha, 
Pterosauria or Dinosauria is just as valid conceptually as the hypothesis Aves 
is a clade in Dinosauria.  The problem with current uses of the term thecodont 
by BANDits is that they have no clear definition of Thecodontia, so include 
even such non-archosauriforms as Longisquama and drepanosaurids.  If they 
define it, problem solved.
 
Mickey Mortimer