Message 2001-02-0038: Genera as Clades

Thu, 08 Feb 2001 15:51:24 -0500 (EST)

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Date: Thu, 08 Feb 2001 15:51:24 -0500 (EST)
From: "T. Mike Keesey" <tmk@dinosauricon.com>
To: -PhyloCode Mailing List- <PhyloCode@ouvaxa.cats.ohiou.edu>
Subject: Genera as Clades

My website, the Dinosauricon, is an attempt to catalogue all
non-neornithean Ornithodira. The site is generated programmatically from
databases.

For the next version of my site (which will largely adhere to PhyloCode),
I am planning to implement a new system for genera. I'm not proposing it
as a solution that PhyloCode should adopt, but I thought it might spark
some discussion.

Basically, every genus is seen as a stem-based clade with its type species
as the internal specifier and *every single other type species* as
external specifiers. ICZN rules will be used to determine what is and
isn't a valid type species.

If I left it at this, the system would be fairly objective, but would lend
itself to oversplitting. Hence, I'm going to (regrettably) add the
capability to arbitrarily suppress certain generic names.

Some species may not fall into any generic clades. These will be cited
with the original genus they were published under, with the generic name
in quotes.

Examples:

I. Higher Tyrannosaurini

_Tyrannosaurus rex_ Osborn 1905 is a type species by ICZN rules.
_Tyrannosaurus bataar_ Maleev 1955 is the type species of _Jenghizkhan_
Olshevsky _vide_ Olshevsky, Ford & Yamamoto 1995. _Tarbosaurus efremovi_
Maleev 1955 is also a type species. _Jenghizkhan_ will be arbitrarily
suppressed to prevent oversplitting.

_Tyrannosaurus_ becomes Clade(_T. rex_ <-- all other unsuppressed type
species), and _Tarbosaurus_ becomes Clade(_T. efremovi_ <-- all other
unsuppressed type species). Under most present phylogenies, this would
make _T. bataar_ a species of _Tarbosaurus_, not _Tyrannosaurus_ as
originally thought.

(I may decide to suppress _Tarbosaurus_ as well, in which case all three
of these species would fall under _Tyrannosaurus_.)

II. Mononykini

_Mononykus olecranus_ (Perle, Norrell, Chiappe & Clark 1993), _Parvicursor
remotus_ Karhu & Rautian 1996, and _Shuvuuia deserti_ Chiappe, Norell &
Clark 1998 are all type species. _Ornithomimus minutus_ Marsh 1892 is not.
(_O. velox_ Marsh 1890 is the type species of _Ornithomimus_.) Given this
phylogeny (which _O. velox_ is a distant outgroup to):

--+--_M. olecranus_
  |--_O. minutus_
  |--_P. remotus_
  `--_S. deserti_

_O. minutus_ does not belong to any of the stem-based generic clades, so
it is cited with quotes around its original genus: _"Ornithomimus"
minutus_.

Note: further resolution to the above phylogeny could conceivably result
in _"O."  minutus_ being assigned to _Mononykus_, _Parvicursor_, or
_Shuvuuia_.

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Again, I don't intend this as a serious proposal. The arbitrary nature of
the suppressions goes against the spirit of PhyloCode. But perhaps the
suppressions are not as necessary as I make out? Has anything similar been
proposed?

_____________________________________________________________________________
T. MICHAEL KEESEY
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