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Re: Me vs. Makovicky et al.- comparison and consensus



On 10/18/05, Roberto Takata <rmtakata@gmail.com> wrote:
> 2005/10/18, T. Michael Keesey <keesey@gmail.com>:
> > This is rather odd, since, as recently noted on the list,
> > "oviraptorosaurs" are listed as one of the externals specifiers for
> > _Therizinosauria_. So if any of the internal specifiers for
> > _Therizinosauria_ are closer to _Oviraptor_ than to birds (and several
> > analyses posit so for all of the internal specifiers), their
> > definition of _Therizinosauria_ yields an empty taxon!
>
> Not necessarily so. Therizinosauria would be Oviraptorosauria closer
> to _Therizinosaurus_ than to _Oviraptor_. As Carnosauria is Theropoda
> closer to _Allosaurus_ than to _Passer_

Once again, the definitions in Currie & Padian (eds.) 1997:

"Therizinosaurs include six described genera (_Alxasaurus_,
_Enigmosaurus_, _Erlikosaurus_, _Nashiungosaurus_ [sic],
_Segnosaurus_, and _Therizinosaurus_) ... Therezinosaurs [sic] may be
defined as the aforementioned taxa and all others closer to them than
to oviraptorosaurs, ornithomimosaurs, and troodontids."

"Oviraptorosauria may be defined to include Oviraptoridae and all taxa
closer to _Oviraptor_ than to birds."

Nothing can be closer to the six therizinosaur specifiers than to
oviraptorosaurs if they themselves are oviraptorosaurs. Ergo, the
definition yields an empty taxa (if any of the therizinosaur
specifiers share more recent ancestry with _Oviraptor_ than with
birds, at least).

Consider it this way: what if you defined _Saurischia_ as all  taxa
closer to _Megalosaurus_ than to archosaurs? Well, _Megalosaurus_ *is*
an archosaur, so there can't be anything closer to it than to
archosaurs.
--
Mike Keesey
The Dinosauricon: http://dino.lm.com
Parry & Carney: http://parryandcarney.com