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RE: Suchosaurus, Baryonyx and Martinavis
Mike Keesey wrote:
> I knew it seemed familiar.
Yes, I could almost hear you rolling your eyeballs. ;-)
> But isn't that a separate matter, to do with the selection of
> neotypes? The only instances I see in the ICZN of the word "dubium" is
> in articles about the selection of a neotype.
The selection of neotypes is a separate issue; here the ICZN cites the term
nomen dubium explicitly. However, the principle behind a nomen dubium comes up
elsewhere implicity - specially with this hierarchial typification issue.
>> "Objectivity provided by typification is continuous through the
hierarchy of names. It extends in ascending order from the species
group to the family group.
>> Thus the name-bearing type of a nominal species-group taxon is a
specimen or a set of specimens (a holotype, lectotype, neotype or
syntypes [Art. 72.1.2]),
>> that of a nominal genus-group taxon is a nominal species defined
objectively by its type; that of a nominal family-group taxon is the
nominal genus on which its
>> name is based."
>> So to return to the current example... if _Troodon formosus_ is not
*taxonomically* valid at the level of species, then the genus is not
valid (because of the
>> nature of its type).
> But it is taxonomically valid, since it was validly published, isn't it?
If a name is validly published, it is *nomenclaturally* valid, I would say.
Nomenclatural validity is determined by the ICZN, and is objective (at least in
Taxonomic validity, on the other hand, is entirely subjective. For example, if
I found two separate genera with _Troodon_ teeth, I can publish a paper
claiming that _Troodon formosus_ is a nomen dubium. As a nomen dubium, the name
is restricted to the type, and no further material can be assigned to it; thus,
the name is removed from taxonomy. But, no matter how compelling my arguments
are, my claim that _Troodon_is a nomen dubium is all based on my subjective
interpretation of the material. (Same goes for the determination of subjective
> Wouldn't this have more to do with species-group names that somehow
> did not meet the requirements of publication, thereby being nomina
> nuda (and thereby making any genus-group names typified by them nomina
> nuda, and any family-group names typified by those genus-group names
> nomina nuda)?
I wondered about that too. But the principle of hierarchial typification should
also apply to when a nominal species is a nomen dubium. Also, most nomina nuda
arise because there is NO type at all: the actual publication in which the name
appears meets ICZN criteria, but no type or description was provided.
> Your usage of "valid" (i.e. diagnostic) is not the same as what I
> thought the ICZN's usage was (i.e., validly published and not
>>From the ICZN's online glossary:
> "valid, a. (validity, n.) Of an available name or a nomenclatural
> act: one that is acceptable under the provisions of the Code and, in
> the case of a name, which is the correct name of a taxon in an
> author's taxonomic judgment."
> "[I]n an author's taxonomic judgment." That's pretty vague, but I
> think it means judgment concerning synonymy. I.e., a valid name is an
> available name that is not also a junior synonym.
Yep. But although there is a clear connection, taxonomic validity and
nomenclatural validity are different entities. Where hierarchial typification
is concerned, changing taxonomy can change the associated nomenclature of
'ranked' taxa (=coordinated family-level taxa). Otherwise, we would use
Deinodontidae instead of Tyrannosauridae, or Podokesauridae instead of
> Since the holotype specimen is so poor, we can't be very sure whether
> _Troodon formosus_ and _Stenonychosaurus inequalis_ are synonyms. If
> they are, _T. formosus_ is the valid name. If they aren't, then both
> are valid names. In either case, both are available names. In no case
> is _T. formosus_ invalid (although it may be a candidate for a
Oh yes, _Troodon formosus_ is certainly a valid name - in the nomenclatural
> I would disagree in the case of eponymous names. _Ceratops montanus_
> might not be well-known, but it should not be permissible for it to be
> outside of _Ceratopsidae_.
Yep. And there's the rub. It is often difficult to assign a fragmentary taxon
to a given family. How confident are you (or anybody) that _Ceratops montanus_
can be assigned to Ceratopsidae? All we have for _Ceratops montanus_ are an
occipital condyle and a pair of horn cores.
> Isn't _Deinodon_ specifically a nomen oblitum, though?
I wasn't aware of this. To be a nomen oblitum a name must not appear in the
literature for 50 years after its publication, and I don't think _Deinodon_
> Let's come back to that in a decade or two....
That's October 3, 2027. Save the date! :-)
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