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Re: Lumping Spinosauridae Redux

--- "Jaime A. Headden" <qilongia@yahoo.com> wrote:

> 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.

At what time? Sorry, I still don't follow.
> <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.*

No, _Suchomimus_ would be a clade and _walkeri_ a species. Different types of

If _Suchomimus_ = genus(_tenerensis_), _Baryonyx_ = genus(_walkeri_), and
_tenerensis_ = _walkeri_, then it follows that _Suchomimus_ = _Baryonyx_.

> 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.

But the provisional definitions rests on species, not on specimens. I think
that's what you're missing.

>   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.

I agree there; I don't even think there is an objective definition of species,
at least not as presented to date.

=====> T. Michael Keesey <http://dino.lm.com/contact>
=====> The Dinosauricon <http://dinosauricon.com>
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