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Re: Lumping Spinosauridae Redux



> Date: Mon, 20 Sep 2004 14:20:04 -0700 (PDT)
> From: "Jaime A. Headden" <qilongia@yahoo.com>
> 
> <Here's my take on this.  To define any kind of higher group, in these
> enlightened days, we need at least two specifiers: either two ingroups
> (for a node) or an ingroup and an outgroup (for a stem).  (Here I am
> ignoring apomorphy-based clades, and quite right, too.)  The magic of the
> "genus" (and the "species", which is arguably no less illusory for fossil
> animals) is that you're allowed to define it on only one specifier. 
> (Actually, you don't have to define it at all, but if you do, you only
> need one specifier.)  For example:
> 
> * Species _Baryonyx walkeri_ = specimen BMNH R9951 and all other  
> individuals that are pretty damned similar to it.>
> 
>   This is how J. Clarke has been defining her species.
> 
> <* Genus _Baryonyx_ = specimen BMNH R9951 and all other individuals that
> are quite similar to it but not necessarily _that_ similar.> 
> 
>   I don't understand ... how similar is "not too similar"? What's the
> metric?

Pre-CISE-ly!

My new and perhaps indefensible position (I don't know if I can defend
it, I haven't tried yet) is that it makes pragmatic sense to have a
notion either of genus or species for fossil taxa (because it's useful
to be able to name a taxon on a single specifier), but that it's
essentially meaningless to have both, since there is no way to
establish the boundaries between them.

>   ... 'Sides, I don't need anyone to agree with me, just acknowledge
> and practice science.

Well, if what you're discussing is taxonomy (as it is here), then you
absolutely do need people to agree with you, otherwise you can't
communicate.  Case in point: it's as confusing as hell that different
authors at different times have used "Diplodocidae" to indicate
(roughly) the groups (_Diplodocus_ not _Saltasaurus_), (_Diplodocus
not _Dicraeosaurus_) and (_Diplodocus_ not _Apatosaurus_).  Since
taxonomy is language, and the purpose of language is communication,
and communication is only possible when there's agreement on the
meaning of words, then in these areas we need agreement.

(But, no, of course you don't need people to agree with your ideas
about biomechanics, palaeoecology, etc.)

 _/|_    _______________________________________________________________
/o ) \/  Mike Taylor  <mike@indexdata.com>  http://www.miketaylor.org.uk
)_v__/\  "When the seagulls follow the trawler, it is because they
         think sardines will be thrown overboard" -- Eric Cantona.
         Yeah, right.

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