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Re: tiny-armed theropods
Mickey Mortimer <email@example.com> wrote:
> I don't know where you got the idea that nomina dubia aren't taxa or
> organisms. Troodon formosus is a real animal, diagnostic
> holotype or not. There was a living organism which the type tooth of Troodon
> belonged to, and this individual can be included in a
> phlogenetic analysis, regardless of whether additional individuals could be
> assigned to its species.
Of course the tooth of _Troodon formosus_ came from a real animal.
I'm not suggesting it was carved out of stone by Cretaceous trolls.
But if a genus is declared a nomen dubium, then it no longer denotes a
real taxon. For example, the teeth named _Deinodon horridus_ (a nomen
dubium) could belong to any number of tyrannosaurid species. So
although the teeth came from a real individual, that individual does
not represent a distinct taxon. Thus, it would serve no purpose to
code the teeth and put them into a phylogenetic analysis. Yes, you
*could* put _Deinodon_ into a phylogenetic analysis. But it's like a
dog chasing a car: it can be done - but what's the point?
> There's no rule that says only taxa or only valid taxa can be included in
> such analyses.
Yes, I know. But since a nomen dubium no longer represents a real or
distinct taxon, it's removed from taxonomic consideration. Sticking a
nomen dubium into an analysis is just going through the motions. It's
not advancing the scientific process in any way. The only reason you
would include a nomen dubium in an analysis is if it happens to be a
name-nearing taxon of a clade, which strikes me as circular reasoning.
I'd prefer that nomina dubia be excluded from clade definitions.
> The microraptorian NGMC 91 is included by Senter (2007) for instance, despite
> being only a single individual that has not been
> conclusively differentiated from Sinornithosaurus. Indeed, it has only been
> described as Dromaeosauridae gen. et sp. indet. and
> Sinornithosaurus sp. indet..
IMHO this is irrelevant. If NGMC 91 is recovered as a distinct taxon
in the analysis, then it is no longer indeterminate. On the other
hand, if it cannot be conclusively differentiated from
_Sinornithosaurus_, and can be conclusively differentiated from other
dromaeosaurids - then NGMC 91 belongs in _Sinornithosaurus_.
> What's the point of having a rulebook for a community if they only follow the
> rules they want to anyway? It's like enforcing laws only
> when they don't inconvenience you. We might as well just get rid of the ICZN
> if we're going to call it wrong when we don't like what it
Well, now that you mention it... :-) I have repeatedly opined that
the ICZN Code should *not* apply to family-level taxa (family,
subfamily, tribe, superfamily), only to genera and species. So while
I don't advocate completely getting rid of the ICZN, it's focus should
be removed from family-level taxa. It just causes too many problems
when phrasing sensible phylogenetic definitions.