Re: Strange thoughts on PN - was Re: BAD vs. BADD

[Mike Taylor <mike@indexdata.com>]

David Marjanovic writes:
 > > Dinsauria=(Megalos+Iguanodon)
 > > Aves=(Archaeo+Passer)
 > > Classicodinosauria (or whatever) = Dinosauria without Aves
 > >
 > > just because this grouping is so useful...
 > 
 > Is it so useful?
 > 
 > Isn't it less useful than:
 > 
 > - primarily flightless dinosaurs

... which is a paraphyletic ground made by removing an apomorphy-based
clade from Dinosauria.

 > - primarily wingless dinosaurs

... which is a paraphyletic ground made by removing an apomorphy-based
clade from Dinosauria.

 > - primarily featherless dinosaurs

... which is a paraphyletic ground made by removing an apomorphy-based
clade from Dinosauria.

 > - Mesozoic dinosaurs

... which is a totally arbitrary group hardly related to evolutionary
concepts at all.

 > - non-neornithean dinosaurs

... which is a paraphyletic ground made by removing a crown clade from
Dinosauria.

 > - extinct dinosaurs (now _that_ is paraphyletic!)

... which is equally aritrary.

There is a sort of definitional apartheid going on here whereby some
kinds of paraphyletic group are somehow seen as less legitimate than
others.  David is not alone in his distain for the group formed by
removing Aves from Dinosauria; but neither am I alone in liking that
group.  (And I don't give a rat's arse about birds :-)

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