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Re: Coelophysis/Rioarribasaurus



From: "King, Norm" <nking.ucs@smtp.usi.edu>
 > I reiterate that many of the comments made by people here (including the
 > above by Dinogeorge!) support my contention that the
 > Coelophysis/Rioaribasaurus situation could have been handled better.

Definately.  But only in that I think the appeal to the ICZN was
unnecessary and ill-concieved.

 >  I
 > suspect Lagosuchus/Marasuchus could also.

I don't think so.

I read the paper that made the revision.  It was properly written,
concise, and to the point.

I did not find their arguments for the insufficiency of the Lagosuchus
type material convincing.  But that is a different issue, distinct
form the proper way of dealing with such matters.  If I want to
make an issue of this, I should write a paper refuting their arguments
and submit it to a journal.

[Mind, the article did make a reasonable case that at least two species
are present in the the material originally refered to Lagosuchus].

 > >Yes, by disregarding the differences between the type specimens.
 > >This is a good thing? Why not return to the days of the 19th century,
 > >when all pterosaurs were described as species of _Pterodactylus_, all
 > >theropods were described as either _Megalosaurus_, _Deinodon_, or
 > >_Laelaps_...[snip]...The point of creating a diagnosis is to
 > >_distinguish_ a taxon from its close relatives of similar morphology.
 >
 > I guess I have to work on the clarity of my statements.  I am not
 > contending that a better diagnosis wasn't needed, but that we could have
 > found a better way to shuffle the names in question.

There are only a few ways possible, without a ruling from ICZN.

The name Coelophysis *must* refer to the taxon including the original
type material.  There is no choice on this.

So we can have:

        - One species: Coelophysis bauri.
        - Two species, one genus: Coelophysis bauri + C. colberti
        - Two genera: Riarribasaurus colberti, Coelophysis bauri

There *are* no other possibilities. (Well, a different name could
have been chosen for Rioarribasaurus :-)

Any other choice requires a ruling by the ICZN setting aside the
normal rules.

 >  _Coelophysis_ could
 > have been retained for the well-known specimens which have historically
 > been referred to that genus.

That is what the appeal to the ICZN is trying to acomplish.

Without an ICZN ruling this is only possible if the Petrified Forest
specimens are considered to be congeneric with the Ghost Ranch specimens.

In other words, you are arguing in *favor* of the appeal to the ICZN,
and suggesting that the ICZN support the requested change of type
material.

I am always hesitant to refer a matter to the ICZN.  I believe that
should be restricted to special circumstances.

For instance, when it appeared that Centrosaurus (the dinosaur)
was pre-empted by a long unused non-dinosaurian Centrosaurus
(a junior synonyn of something else??), I supported getting the
ICZN to rule the older Centrosaurs a "forgotten name".

[By the way, what *is* the current status of this matter?]
 >
 > That's a good point, but in the current debate we're talking about just
 > one(?--we'll see, right?) animal from one location that has always been
 > known by the well-known name in question.

It is either one animal from *two* locations, or two animals.

I actually suspect that the two forms *are* distinct species.
 >
 > >and all of the nearly 40 species of cats would be
 > >subsumed under the name _Felis_...
 >
 > But I believe my cat is still _Felis_, and my dog is still _Canis_.

That is because the first cat species *named* was the domestic cat,
by Linnaeus himself, and ditto for the dog.  This makes the domestic
species of each the type species of their respective genera. The rules
thus require that *no* *matter* *what* *else* one does, the names Felis
and Canis *must* refer to the taxon that includes the domestic forms.

Even if we placed the domestic cat in its own genus, by itself, that
genus would be _Felis_, even though this would mean placing all of the
Eurasian wild cats into some other genus. [Of course in reality he
Eurasian wild cats are so similar to the domestic cat that placing
them in a separate genus would be absurd, so the issue doesn't come
up].

Similarly for the dog.
 >
 > Which author?

Whichever author is writing the document that uses the names.

 > Different authors don't agree!

True.  That is their right.

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

The peace of God be with you.