Message 2002-04-0020: Re: genus definitions

Wed, 01 May 2002 18:47:06 +0200

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Date: Wed, 01 May 2002 18:47:06 +0200
From: David Marjanovic <>
To: PhyloCode mailing list <>
Subject: Re: genus definitions

> I think it works pretty well, except for one or two pitfalls. One is that
> need to arbitrarily suppress some generic names which are not commonly

Simply don't convert them. :-)

> But with this style of definition, _ostromi_ and _comahuensis_ could be
> designated as types of their own clades, and thus excluded from
> _Archaeopteryx_.
> On the other hand, this could be abused if, for example, someone decided
> make _Homo neanderthalensis_ the type of a new clade, thus excluding it
> _Homo_ AND excluding _erectus_, _habilis_ etc. from any clade more
> than _Hominina_. Just as it could be used to preserve stability (as in the
> _Archaeopteryx_ example), it could be used in a destabilizing manner.

You could change the definition to "than with any (other) species designated
as a type species under the preexisting codes". This would also be available
for new clade names; everyone could make *Homo sapiens neanderthalensis* the
type... I think subspecies of a new clade, but that clade would be a part of
*Homo* because *neanderthalensis* hasn't been a type (sub)species of
anything so far, as far as I know, and would therefore not be excluded from
*Homo*. It would also present a convenient approach to convert subgenera and
superspecies (a few exist among the beetles, and in 19th century pterosaur
systematics). Of course this would destroy your example of how stability
could be preserved should that short-sighted definition of *Archaeopteryx*
be converted (under some phylogenies, it would include the entire
Dromaeosauridae and its close relatives... *Velociraptor*, *Deinonychus*,
*Utahraptor*, *Bambiraptor*, all!).
        On the whole I think this should be decided case by case;
*Crocodylus* has got a node-based definition that seems to work (but I don't
know the relevant literature!).


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