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Re: "Phylogenetic Definitions and Nomenclature..."



On Thu, 25 Mar 1999, Thomas R. Holtz, Jr. wrote:

> At 01:24 PM 3/24/99 -0500, T. Mike Keesey wrote:
> 
> >Doesn't the definition in The Encyclopedia of Dinosaurs 
> >{_Deinonychus_ > birds} have priority?
> 
> I'd forgotten about that one.  Yeah, it should.  In fact, the definitions in
> Encyclopedia of Dinosaurs were from the version of Padian, Hutchinson &
> Holtz that was originally reviewed (the paper has been "in press" for a
> while).  The plan was to get the paper out first, but such are the vagaries
> of publication and peer review.

Well, that's a relief. Some of Sereno's definitions are rather ... I'll
just be polite and say they don't seem to consider that his phylogeny has
the slightest chance of being wrong.

One exception, though: very nice definitions for the three allosaur
families: 

Allosauridae == {Allosaurus > Sinraptor, Carcharodontosaurus,
Cryolophosaurus, Monolophosaurus}

Carcharodontosauridae == {Carcharodontosaurus > Allosaurus, Sinraptor,
Monolophosaurus, Cryolophosaurus}

Sinraptoridae == {Sinraptor > Allosaurus, Carcharodontosaurus,
Monolophosaurus, Cryolophosaurus}

Unfortunately, unless I'm mistaken, the Encyclopedia's ones have priority!

Allosauridae == {Allosaurus > Sinraptor}
Sinraptoridae == {Sinraptor > Allosaurus}
(no definition of Carcharodontosauridae -- Sereno's is the only one I know
of)

Meaning that Carcharodontosauridae is either

(a) outside Allosauroidea {Allosaurus + Sinraptor}, in which case all's fine
(b) inside either Allosauridae or Sinraptoridae!

In case (b), we have either the nasty possibility of an "-idae" inside
another "-idae", or we bend the rules a bit and change the name of
Carcharodontosauridae to Carcharodontosaurinae.

And to top it off, everyone seems to have an unresolved trichotomy of
these three. Except, I guess, for those who think carcharodontosaurids are
abelisaurs -- in which case Carcharodontosauridae becomes a junior
subjective synonym of Ceratosauria {Ceratosaurus > Neornithes}.

Actually, his explicit definition is "all *allosauroids* closer to Ca. 
than to either A., M., Cr., or S." (emphasis mine). By either definition
of Allosauroidea, the "abelisaur hypothesis" renders Carcharodontosaurus a
non-allosauroid. So would this turn Carcharodontosauridae into a null
group? 

Ack!

--T. Mike Keesey                                    <tkeese1@gl.umbc.edu>
WORLDS                                  <http://www.gl.umbc.edu/~tkeese1>
THE DINOSAURICON                               <http://dinosaur.umbc.edu>