Re: proper name for coelophysis

[Stan Friesen <swf@ElSegundoCA.ATTGIS.COM>]

>From: bonn@qcvaxa.acc.qc.edu ("Bonnie Blackwell, x 3332")
 > 
 > i recently read in lucas' textbook that _Rioarribasaurus_ is the new
 > name for _Coelophysis_.  Has this name been accepted generally by the 
 > dinosaur
 > community?  I note in mail messages from the listserver by several people,
 > that they are still using _Coelophysis_.  Opinions please...
 > thx

Well, *I* am certainly hesitant to accept it.

The basic argument *for* it is that the type specimen of Coelophysis
is too fragmentary and damaged to be really identifiable, so the
Ghost Ranch theropod cannot properly be refered to Coelophysis.
[An species name with an unidentifiable type specimen is held
to be restricted to just the type specimen - this is indicated
by the use of the term "nomen dubium"].

So, what has happened is that the name Rioarribasaurus has been
proposed as the name for the Ghost Ranch theropod, on the assumption
it cannot be included in Coelophysis.  Those who believe that
Coelophysis is a nomen dubium, accept Rioarribasaurus.

Now, part of my problem here is that I feel some people are too
quick to declare a specimen a nomen dubium.  For instance some
strict cladists consider any specimen that does not show an
identifiable apomorphy to be a nomen dubium.  I think this is
unnecessary.  At the species level metric evaluation of normal
intra-specific variation combined with biogeographic data
can be sufficient to identify a specimen adequately for
assignment to a species.

Thus, for now, and until a second contemporaneous species that
is "indistinguishable" from the Coleophysis type specimen is
discovered, I will consider the referal of the Ghost Ranch
series to Coelophysis to be adequately warrented.

[Actually, I believe the same person who proposed Rioarribasaurus
has suggested that there are two species present at Ghost Ranch,
but I think most other workers believe the two morphs are male
and female of one species].

swf@elsegundoca.attgis.com              sarima@netcom.com

The peace of God be with you.