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The Unbearable Consequences of Undiscovered Phylogeny [was: Re: "The X Digit"...a Pteroid bone??]



T. Mike Keesey wrote:
>Man, this would wreak havoc with the content of some clades -- Ornithodira
>{Pterosauria + Dinosauria} would include pseudosuchians, _Euparkeria_,
>etc. (not to mention prolacertiforms). Dinosauromorpha 
>{Dinosauria > Pterosauria} would be come virtually identical  to
>Archosauriformes.
        C'est la vis. At least one of these taxa, Ornithodira was first
named as a phylogenetic taxon (AFAIK). Thus, while *you personally* may have
some preconcieved notions about what it should contain, there is no problem
with access to the literature, because there is no pre-PT literature on the
taxon. Once there is no problem with pre-PT literature, we all lose the
right to bellyache. As George makes clear (from his own way), if you can't
deal with this sort of problem, you might want to drop PT. ;)

        BTW: I see you use the new Buchholz-Wagner shorthand. Thanks, and
how's it coming?

>If this were the case, abandonment of Ornithodira
        NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO nononononononononononono!
This is not what PT is for at all. We don't "abandon" taxa because they no
longer contain what we thought they did. That's exactly what PT is *not*
about. You must embrace the change, and its phylogenetic implications.
Phylogeny directs out taxonomy, PT is about divorcing PT from a priori
notions of taxonomy (except, IMHO, insofar as it imperils access to the
literature. You get one shot to get this right, and so far it seems to be
getting boffed, again IMHO.)
        
>and refinement of the definition of Dinosauromorpha {Dinosauria > Pterosauria,
>Pseudosuchia} might be a good idea. 
        Well, you know my feelings on this. I'm always up for multiple
exclusive anchor taxa for stem-based definitions. Unfortunately, we have no
means currentlyu available to alter an established definition. I'm not sure
if Dinosauromorpha is pre-PT or not (I doubt it). If it were, you could at
least make a case for this.

------------------------------------------

George O. wrote:
>One of the reasons I'm not a terribly enthusiastic advocate of strictly
>cladistic taxonomy.
        This is *NOT* a "strictly cladistic" taxonomy, it is a "Phylogenetic
Taxonomy". Cladists use a number of different taxonomic schemes. As far as I
know, in order to be "strictly cladistic", a taxonomy must merely eschew
paraphyly, and I believe you're supposed to make taxon rank (if present)
accord with clade rank, or something like that. Personally, I don't muck
about with modifying Linnean systematics myself.

        :)
        Wagner

--------------------------------------------------------------------------------
     Jonathan R. Wagner, Dept. of Geosciences, TTU, Lubbock, TX 79409-1053
 "Only those whose life is short can truly believe that love is forever"-Lorien