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Use of Genera



I've been giving some thought to the use of genera lately. As some people on
the list may know, when I launched the new version of The Dinosauricon, I
decided to use a provisional system, wherein genera are used as stem-defined
clades, with the type species as the internal specifier and all type species of
all other genera as external specifier. (E.g., _Tyrannosaurus_ would be defined
as "the first ancestor of _rex_ Osborn 1905 which is not also an ancestor of
another type species, plus all of its descendants.")

But there are certain flaws with the system. It undermines stability in two
ways. One, it grants validity to genera not commonly in use. For example, if
applied to hominids, _Pithecanthropus_ would have to be revived (for _erectus_;
which, incidentally, I believe leaves _habilis_ without a "genus").

Furthermore, it does not guarantee the content of any "genus". _Homo_ might
consist of _sapiens_ and _neanderthalensis_ for now, but what if some
overzealous paleoanthropologist names a genus for _neanderthalensis_? _Homo_
will be reduced without its definition even being changed.

I've decided that, in this case, stability is really important. These are the
organisms' *names*; they shouldn't be in constant flux. Therefore, I've decided
to implement another system on The Dinosauricon: the original system.

When I say stability, I don't mean with literature from 10 years ago, or 50
years ago. I mean all literature spanning the history of formal biological
nomenclature.

The concept of Genus was originally much different from what it has become,
much broader. As an example, Linnaeus' Primates (equivalent, more or less, to
Archonta) was divided into four genera: _Vespertilio_, _Lemur_, _Simia_, and
_Homo_. Are more really necessary?

Broadening the concept of Genus not only enforces stability over the course of
*all* literature, but also reduces bickering about which species belongs where.
Should _boisei_ and _robustus_ be placed in _Australopithecus_ or
_Paranthropus_? No, just put them in _Homo_ and have done with it.

I have decided to place all non-neornithean dinosaurs in six genera:
_Iguanodon_, _Megalosaurus_, _Hylaeosaurus_, _Cetiosaurus_, _Plateosaurus_, and
_Archaeopteryx_. Expect to see binomina like _Iguanodon horridus_,
_Megalosaurus rex_, _Cetiosaurus excelsus_, _Archaeopteryx regalis_, etc.

Gone will be the unproductive arguments about whether to synonymize
_Tarbosaurus_ and _Tyrannosaurus_, _Ornithomimus_ and _Struthiomimus_, etc. --
all _Megalosaurus_ now.

Still got to figure out how to handle trivial homonyms (is _M. rex_ the
tyrannosaurid, the basal theropod, or the basal tetanuran?). Perhaps I'll
convert old genera (_Megalosaurus alwalkeria_, _Megalosaurus edmarka_, etc.)

Working on the changes now; expect to see them in a few weeks. Any comments?



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