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Re: SVP Preview

--- npharris@umich.edu wrote:
> Quoting Dinogeorge@aol.com:
> > formation of names, you quickly lose track of where things are in the 
> > hierarchy. Quick, without looking it up, tell me how these taxa might be 
> > nested: Dinosauromorpha, Dinosauriformes, Dinosauria, Eudinosauria, 
> > Dinosauroidea. Or Sauropoda, Eusauropoda, Macronaria, Titanosauriformes, 
> > Titanosauromorpha, Somphospondyli, Titanosauria, Diplodociformes, 
> > Diplodocimorpha. But given, e.g., Tyrannosauria, Tyrannosauroidea, 
> > Tyrannosauridae, Tyrannosaurinae, Tyrannosaurini, and Tyrannosaurina, once 
> > you know the endings convention, you can immediately see that those names
> are
> > in a nested sequence, rank or no rank.
> Yes!  This is precisely a point I tried to make some months ago.  Why is it 
> that (at least some) pracititioners of PT on this list don't see this as a
> good thing?

Because it rests on the assumption that a given phylogeny is real.

Hierarchies may change, depending on the phylogeny. For example, _Maniraptora_
may include _Tyrannoraptora_, or _Tyrannoraptora_ may include _Maniraptora_,
but they will always refer to the same definitions. (_Maniraptora_ =
Clade(_Vultur gryphus_ <- _Ornithomimus velox_), _Tyrannoraptora_ =
Clade(_Tyrannosaurus rex_ + _Vultur gryphus_), if I may emend these to
PhyloCode-acceptable forms).

Under Sereno's phylogeny:

Maniraptora (although he uses this name for a less inclusive taxon)
   `--(Maniraptora sensu Sereno)

Under Holtz's old phylogeny:

Maniraptoriformes =Tyrannoraptora

Under various newer phylogenies (including Holtz):


Now, if these names were given ranked endings *and expected to follow them*,
they might fail.

A small sacrifice to pay for explicitness. I'd far rather have
_Tyrannosauroidea_ defined as "the first ancestor of _Tyrannosaurus rex_ which
is not also an ancestor of _Vultur gryphus_ or _Ornithomimus velox_, plus all
of that ancestor's descendants" than "the superfamily (whatever that means)
including _Tyrannosaurus rex_".

On another note, if Sereno first defined _Torvosauroidea_ using an identical
definition to his definition for _Spinosauroidea_, then, under PT,
_Torvosauroidea_ should have priority. Once again, they aren't superfamilies
(although superfamilies with the same name might exist under traditional,
ICZN-based taxonomy) -- they are phylogenetic taxa, clades with no absolute
rank. As with species, priority should be assigned by date of explicit
definition, not by date of coinage.

Of course, anyone is free to use traditional taxonomy and ICZN rules for higher
taxa (certainly a vast number of researchers do) -- just don't expect
practitioners of phylogenetic taxonomy to follow.

=====> T. Michael Keesey <keesey@bigfoot.com>
=====> The Dinosauricon <http://dinosauricon.com>
=====> BloodySteak <http://bloodysteak.com>
=====> Instant Messenger <Ric Blayze>

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