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What, if anything, is _Apatosaurus_ (Was: Ceratops (was RE: Pterosaur diversity (was: Re: Waimanu)))
Michael Mortimer writes:
> Upchurch et al. (2004) found that none of the original apomorphies
> of Apatosaurus (also from 1877) are valid anymore. And of the
> eleven apomorphies they consider valid for Apatosaurus, four are
> seen in other sauropods, while five can only be observed in one
> specimen of Apatosaurus and involve bones not commonly found in
> sauropods (braincase, atlus, astragalus). And this is Apatosaurus!
> An extremely distinctive genus known from multiple fairly complete
I admit this kind of talk worries me. We all know what _Apatosaurus_
is. A while back, someone on this list came up with the idea of "the
pornographic definition of birds" which is "I know one when I see
one". That's sort of how I feel about _Apatosaurus_. 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.
> Using Wilson and Upchurch's criteria, very few sauropod genera
> would be valid.
Really? What are the criteria that you allude to exactly? That each
valid genus should be diagnosed by at least one autapomorphy? I would
think that most sauropod genera have that.
>> 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.
/o ) \/ Mike Taylor <email@example.com> http://www.miketaylor.org.uk
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