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Re: Platecarpus tympaniticus - how to analyze a nomen dubium



On 22 September 2010 10:36, Michael Mortimer <mickey_mortimer111@msn.com> wrote:
>
> Mike Taylor wrote-
>
>> > PhyloCode (which has yet to be implemented) states that if a clade name is 
>> > based on a genus name, that genus must be used as an internal specifier. 
>> > So again, not only must Ceratopsidae (and Ceratopsinae) include 
>> > _Ceratops_, but _Ceratops_ must be included in the definition(s).
>>
>> Actually, I think the PhyloCode leaves enough wiggle-room for us to do
>> what is obviously the right thing here: Article 11.7 is the relevant
>> one, and it says "In the interest of consistency with the rank-based
>> codes, it would be desirable for a clade whose name is converted from
>> a typified name under a rank-based code, or is derived from the stem
>> of a such a name, to include the type of the that name. Therefore,
>> when a clade name is converted from a preexisting typified name or is
>> a new or converted name derived from the stem of a typified name, the
>> definition of the clade name must use the type species of that
>> preexisting typified name or of the genus name from which it is
>> derived (or the type specimen of that species) as an internal
>> specifier."
>>
>> But we don't have to convert the rank-based name Ceratopsia, typified
>> by Ceratops. Instead we can make a brand new clade Ceratopsia,
>> anchored on whatever taxa we want, named not after an included type
>> but after the characteristic morphological feature of the clade's
>> member, i.e. a horned face.
>>
>> That's what I'd do, anyway, if it fell to me.
>
> Er, so you'd erect Ceratopsia Taylor, 201X to replace Ceratopsia Marsh, 
> 1890?  I certainly hope the Phylocode doesn't usher in such ridiculous 
> violations of authorship under the guise of naming clades homonymous with 
> ranked taxa.

It's worse than you think.  So far as the PhyloCode is concerned
authorship of the rank-based taxon and the homonymous clade are
completely separate, so whatever definition I used of Ceratopsia when
defining it as a PhyloCode-govered clade, it would be Ceratopsia
Taylor 201X.  The code suggests an authority-mentioning scheme that is
something like Ceratopsia Taylor 201X [Marsh 1890], which goes some
way to towards addressing this.

Worse, there seems to be no way to cite the originator of a specific
phylogenetic definition or indeed the first explicit user of the name.
 So Marsh used the rank-based family Diplodocidae in 1884, and so is
deemed also to have raised the superfamily Diplodocoidea (by the
Principle of Coordination); Upchurch first used the name Diplodocoidea
in 1995; and Wilson and Sereno defined it phylogenetically as
(Diplodocus < Saltasaurus) in their classic 1998 monograph.  But since
that definition is not governed by the PhyloCode, it would need
re-establishing once the code is enacted.  If I did that, then the
resulting name would be Diplodocoidea Taylor 201X [Marsh 1884], and
neither Upchurch (1995) nor Wilson and Sereno (1998) would get any of
the attribution love.  I think the idea is that the people who first
coined a phylogenetic definition should be encouraged to be the ones
to redefine it under the PhyloCode, but in the case of authors like
Wilson and Sereno who are antagonistic towards the Code and explicitly
don't wish to contribute, what can you do?

I suppose the moral of all of this is that we should be less concerned
with whose personal name appears after the taxonomic name; in
practice, the personal name rarely if ever appears after clade names
anyway, so this may be a bit of a red herring.

Anyway -- back to ceratopsians:

> In this case, even your dishonest non-Ceratops-based Ceratopsia wouldn't work 
> since basal ceratopsians lack horns.

There's nothing dishonest about defining a taxon in such a way as to
include the member that have historically belonged to it.

And nothing that says all members of a clade have to have the
morphological feature that the clade is named after.  A name is just a
label.

> So any claim to have a coincidentally and conveniently similar name merely 
> due to the apomorphy you chose fails since an apomorphy based Ceratopsia 
> would be some neoceratopsian subclade.
>
> Also apomorphy-based definitions suck, but that's another topic. ;)

Woah!  Who said anything about apomorphy-based definitions?  Did you
leap to that conclusion because the etymology of the name Ceratopsia
is "horned face"?  That's confusing definition with etymology.

> Again, I suggest we simply define Ceratopsidae in a way that definitely 
> includes Ceratops (Ceratops montanus <- Protoceratops andrewsi, Leptoceratops 
> gracilis) since the current definition of it being the centrosaur-chasmosaur 
> clade isn't official anyway.  That way follow the ICZN and the Phylocode 
> without any trickery.  Ceratopsia shouldn't even be an issue since Ceratops 
> is obviously a ceratopsian, so (Ceratops montanus <- Pachycephalosaurus 
> gregorii) is just fine as a definition.

I was talking about Ceratopsia, but since you mention Ceratopsidae,
there's no reason we shouldn't define it as (Triceratops horridus <-
Protoceratops andrewsi, Leptoceratops gracilis), give the etymology as
"horned face" (not mentioning Ceratops montanus), and move on.

That seems obviously The Right Thing.  The fact that the clade name
happens to resemble the name of a dubious genus is neither here nor
there.