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Re: ICZN on families based on nomina dubia



Mike Keesey (keesey@gmail.com) wrote:

<The ICZN does not officially mark taxa as nomina dubia (it's a subjective
desgination, up to the author[s] -- right?), so how could it possibly be a
rule?>

  Indeed, there is no such RULE, nor has there ever really been one. There
has, however, been "recommendations" in treating nomina dubia. The reason
nomina dubia are not explicit under the ICZN is because any author may
alter the diagnosis of a previous author and the criteria by which the
taxon being so dubiously assigned can changed with data, so nomina dubia
are by their nature not a "distinct" entity as are nomina nuda, etc. The
same goes for nomina valida. This is why nd and nv are rather ... ill-used
in the literature. Taxa based on such names, as has been pointed out in
the past, have traditionally been treated as less than utile entities, and
a more "diagnostic" taxon used to coin a new containing name, such as the
case with Titanosauridae and Saltasauridae. Ceratopsidae retains a
distinction in that the family is better understood as composed, so the
literature is far more vast and referenced than variation in caudals found
here and there, as in titanosaurids until the recent 80s, 90s, and early
00s. 

  The following posts detail other aspects of the discussion, which Mickey
has been referred to before.

  http://dml.cmnh.org/1998Jun/msg00513.html

  http://dml.cmnh.org/2002Jan/msg00739.html

  Therein, to recap, it should be noted that these recommendations have
been followed nearly without fail for the last 20+ years, and taxonomic
reassignments have been based, so their application has become something
of an unwritten (yet, oddly, written) rule.

  Cheers,

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


                
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