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Re: Typical and less typical types



Just thought I'd add a bit more to clarify the status of nomina dubia...
    There is a distinct difference in all the nomenclatorial codes between
*biologically* valid names and *nomenclatorially* valid names. The
nomenclatorial codes only deal with the latter (the ICZN calls them
"available" names). It is an objective decision as to whether a name
fulfilled the requirements of the Code when it was described. After that, it
is a much more subjective question as to whether the species is identifiably
distinct from other species, etc. There's nothing stopping me deciding for
whatever reason that my recently-deceased cat, for instance, represents the
type of a species distinct from all  other cats, and giving it a name, which
would then be *nomenclatorially* valid if published. It would be quite
unlikely to be *biologically* valid,
    As such, the term "nomen dubium" (while very useful) has no actual
nomenclatorial status (I think these says it's mentioned in the glossary to
the ICZN, in earlier editions it wasn't mentioned at all, and it still makes
no appearance in the actual body of the Code). There decision that a species
is unidentifiable is a subjective one by the researchers, and others may
differ in opinion. Also, more information may become available that allows
the species to be identified (I realise that with some names, probably
nothing short of a time machine will do that, but nevertheless...).
    As such, a so-called "nomen dubium" still remains available for purposes
of priority, homonymy, etc. If I was to decide that _Antrodemus valens_
definitely came from the same species as _Allosaurus fragilis_ (as some
people did for a while), I would *have* to use the name _Antrodemus valens_,
because it was named first (I think :-) ). I couldn't continue to use
_Allosaurus fragilis_ on the basis that _A. valens_ was based on shonky
material. We still use _Allosaurus fragilis_ because we *can't* be certain
that the two are, in fact, the same species.
    The cases mentioned by David are not part of the basic rules. ICZN
judgements refer to cases where, in order to maintain stability and stop
everyone going cross-eyed, the rules actually must be *broken*. As such,
each judgement represents its own individual case, and does not affect the
application of the Code to other names. The ICZN may rule that that a nomen
dubium be suppressed. After that, it can't be used and doesn't take
priority, but because it's now a "rejected" name, *not* because it was ever
a "nomen dubium". Also, a rejected name can never be resurrected except by a
second decision by the ICZN (I don't know of any case where this has
happened, though).
    In cases of ICZN rulings where the holotype is replaced by a neotype,
BTW, the original holotype, again, cannot be resurrected except by another
ICZN ruling (again, I know of no case where this has happened). The original
therefore no longer has any nomenclatorial status. It's different if the
neotype was designated because the holotype was lost or destroyed. Such
cases (which are much more common) don't require an ICZN ruling, and if the
original holotype (spot the tautonymy :-) ) is ever found again, it
automatically resumes precedence.

    Cheers, and hope that all this doesn't confuse everyone too much,

        Christopher Taylor

On 11/8/04 3:16 am, "Ken Carpenter" <KCarpenter@dmns.org> wrote:

> Ah, not quite. Paratypes are all the specimens used to make the original
> diagnosis. A paratype cannot be designated after the fact. A paratype might be
> a headless skeleton and the holotype a skull with a few other bones that tie
> it to the paratype as the same species.
> 
> cotypes are not important anymore since the term is no longer used. We would
> call these syntypes today, a term still in use.
> 
> A holotype is always a holotype, even if the name is declared a nomen dubium.
> The tooth of Paleoscincus costatus (Acad. Nat Sci of Phil. 9263) is still the
> holotype for that taxon even though the name is a nomen dubium. The name is
> just restricted to that specimen.
> 
> 
> Kenneth Carpenter, Ph.D.
> Curator of Lower Vertebrate Paleontology &
> Chief Preparator
> Dept. of Earth Sciences
> Denver Museum of Natural History
> 2001 Colorado Blvd.
> Denver, CO 80205
> 
> Phone: (303)370-6392
> Fax: (303)331-6492
> email: KCarpenter@DMNS.org
> 
> For fun: http://dino.lm.com/artists/display.php?name=Kcarpenter
> 
>>>> David Marjanovic <david.marjanovic@gmx.at> 10/Aug/04 >>>
> In mid-late July there was a discussion on the meaning of holotype, neotype,
> paratype and so on. Here's how I understand the subject:
> 
> 1) Holo-, syn-, co-, lecto- and neotypes are important. Para-, allo- and
> paralectotypes are not.
> 
> 2) Imagine someone finds one new specimen and designates it the holotype of
> a new species. Then a lot of better preserved specimens are found and
> referred to the same species. Then it turns out that they are not the same,
> or that the holotype is undiagnostic. The normal procedure is to pick one of
> the referred specimens as the holotype of a new species. But if this would
> produce too much confusion, someone can petition the ICZN. The ICZN (and
> _nobody else_, ignoring the ICBN...) can then decide to pick one of the
> referred specimens as the neotype of the original species. The original
> holotype _loses its type status_ in the process! The neotype _replaces_ it.
> A species with a neotype has no holotype anymore. -- This has happened with
> *Coelophysis*, and, "one level higher up", with *Iguanodon* (whose original
> type species, *I. anglicus*, is a nomen dubium, so the ICZN has made *I.
> bernissartensis* the new type species; *I. anglicus* is no longer the type
> species of anything).
> 
> 3) Imagine someone finds 5 new specimens that seem to belong to the same
> species (perhaps a growth series). Being in the early 20th century or
> earlier, he designates _all of them together_ the type; they are syntypes.
> This practice has meanwhile been forbidden; the reason is obvious -- who
> guarantees that the syntypes all belong to the same species (as IIRC has
> turned out not to be the case with *Trachodon* and *Chienkosaurus*). Lots of
> syntypes are, however, still haunting around; this is because a first
> revisor is needed for each case. That person picks one of the syntypes and
> declares it the lectotype (lectus, Latin: chosen/picked). The others become
> paralectotypes in the process; as paratypes, they are not of much further
> nomenclatural interest.
> 
> 4) I'm not sure what a cotype is, but I think that's what syntypes are
> called when there are 2 of them (perhaps supposed to show sexual
> dimorphism).
> 
> 5) An allotype is a special sort of paratype, namely one of the opposite sex
> to the holotype. Rare, AFAIK not existing for any Mesozoic dinosaur, and, as
> a paratype, not of any nomenclatural interest. (Except that it probably has
> a heightened probability of becoming the neotype should one ever be needed.)
> 
> I hope all this is correct and helps! :-)
> 
> 
> 
>