RE: What, if anything, is _Apatosaurus_ (Was: Ceratops (was RE: Pterosaur diversity (was: Re: Waimanu)))

[mike@miketaylor.org.uk (Mike Taylor)]

Michael Mortimer writes:
>> The moment you see one of those honking great cervical ribs, you
>> know what you're dealing with instantly.  So how can it be that in
>> a cladistic analysis, such an obviously distinctive character
>> counts for no more than, say, an unobtrustive rugosity on the
>> lateral face of the distal part of pedal phalange II-2?  That's
>> just wrong.
> 
> Well, these apomorphies weren't decided by a cladistic analysis, but
> I agree weighting is a tricky issue.

One of these days, I am going to write an extended rant on character
weighting.  Bottom line: I think the current unweighted-characters
convention amounts to an agreement to bury our heads in the sand.

>>>> 3. If we consider names ending -idae (etc.) to be "family-level"
>>>> and therefore governed by the ICZN, then Wilson and Upchurch
>>>> (2003) are right that Titanosauridae must also die;
>>> 
>>> Er, why?
>> 
>> Because (early in the argument) I posited that _Titanosaurus_ is
>> rightly considered a domen dubium.  If you contest that assumption,
>> the rest of the argument doesn't follow.
> 
> But I noted that the ICZN says NOTHING about nomina dubia.  A taxon
> should merely be "well known" if it has a family-level group named
> after it.

Huh!

> Titanosaurus is well known, wouldn't you say?  Which dinosaur worker
> hasn't heard of it?  I really don't know why Wilson and Upchurch
> (2003) started the whole 'family-level taxa can't be based on nomina
> dubia' myth.  Find the part of the ICZN that says that.  I don't
> think it exists.

That is very interesting.  Re-reading Wilson and Upchurch (2003), I
see that what they actually say is just:

        Based on the evidence given above, the genus
        _Titanosaurus_ is invalid and co-ordinate suprageneric
        Linnean taxa must likewise be abandoned.

There's no appeal to authority -- just an unsupported assertion.

In fact, so far as I can tell, W&U don't quote the ICZN at all in this
paper other than on p. 140 where they mention that names erected in
dissertations are not considered valid.

 _/|_    ___________________________________________________________________
/o ) \/  Mike Taylor  <mike@miketaylor.org.uk>  http://www.miketaylor.org.uk
)_v__/\  "He looks around; he sees angels in the architecture, spinning
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