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Re: Lumping Spinosauridae Redux



Mike Keesey (mightyodinn@yahoo.com) wrote:

<Temporal modifier?>

  The temporal modifier would have to be used to determine, as in crown
clades, membership as a type species _at that time_, permitting authors to
look at the species assignments in a temporal context so as to determine
their own synonymies.

<Not so. If _tenerensis_ and _walkeri_ are the same, then _Suchomimus_ and
_Baryonyx_ are heterodefinitional synonyms (see above).>

  I don't think Mike's system neccessarily allows this to occur, since
*tenerensis* is still the type species of *Suchomimus,* *Suchomimus* will
_always_ be equivalent to *walkeri.* Under the same set-up, using Mike's
definitions for species (as performed by Joyce et al. on turtles and
Clarke on Niobrara Chalk birds), the type specimens are mutually
exclusive, therefore so are the types of each species, therefore so are
the types for each genus. And so forth. They will not be allowed to be
synonymous unless, for example, the two different materials were found to
belong to the same specimen or individual. I see it like this:

  1. a. type specimen of species A = type species of genus A = genus A
     b. type specimen of species B = type species of genus B = genus B

  2. if type specimen of A and B do not belong to the same animal, then 2a
     is true; if the two type specimens belong to the same animal, then
     2b is true:

     a. if the type specimens of A and B are unique, then any clades
        established to contain them are unique from one another and
deserve
        distinct addresses, i.e., clade labels, i.e., names.
     b. if the type specimens of A and B belong to the same animal or
        individual, they pertain still to two different specimens, and are
        catalogued as such. Under the clade address, two unique specimens,
        therefore two unique species, and therefore two unique genera,
        exist.

  3. species that are not types of any genus are not constrained by this,
     and may be put into any other generic container, but themselves
cannot
     be relegated as synonymous species, as their type specimens uphold
     their validity as species.

  Any assignment of synonymy would be subjective on the part of
observation of the material, anyway, and this is how it has been done. I
do not think there is an objective means of referring species into
synonymy, at least not as presented to date.

  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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