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Re: Rioarribasaurus vs. Coelophysis

 From: Jonida@aol.com
 > Speaking of the name controversy, what *is* the current "paleontologically
 > correct" nomenclature for this dino?

This is a "who makes the best case" issue.

The specimens in question are the small theropods from Ghost Ranch.
Traditionally they are considered to be specimens of Coelophysis,
based on apparent similarity to the type specimen of Coelophysis.

However, the type specimen is quite fragmentary, making comparisons
difficult.  In fact it has been suggested that it is so fragmentary
as to be unidentifiable - that is, in taxonomic parlance, a nomen
dubium.  Now, if it is a nomen dubium, no other specimens beyond the
type specimen may be refered to the species, thus requiring a new
name for the Ghost Ranch animal, which is quite well known - hence

So, it boils down to: do you accept the reasoning that led to
Coelophysis being declared a nomen dubium or not?  If you do,
you call the Ghost Ranch stuff Rioarribasaurus, otherwise you
probably continue to call them Coelophysis.

[I am a little heterodox on these issues, I tend to resist
accepting that a specimen is really a nomen dubium unless it
is truly horrendous, so I am still using Coelophysis].

 > I'm compiling a dinosaur manual for the
 > American Museum of Natural History (it's intended for school groups and the
 > like) and have no idea which name to list it under. I'm on the verge of just
 > duplicating the sketch and profile under both names...=P (Unfortunately, I
 > can't say "Rioarribasaurus -- see Coelophysis" (or vice versa) because the
 > booklet has to be comprised of individual pages for kids who write in asking
 > about one particular animal)

Choose one name, and in the text say that the animal is also often
called by the other.

 > If anyone can think of animals that I've missed but should really
 > include, though, I'd appreciate any suggestions. So far, I have: Allosaurus,
 > Apatosaurus, Baryonyx, Brachiosaurus, Coelophysis/Rioarribasaurus,
 > Deinonychus, Dilophosaurus, Gallimimus, Oviraptor, Parasaurolophus,
 > Protoceratops, Stegosaurus, Triceratops, Tyrannosaurus, Utahraptor, and
 > Velociraptor. Possibles include Pachycephalosaurus and Ankylosaurus.
 > Oh, one last query -- I know that Struthiomimus is believed to have been
 > toothless, but did Gallimimus, for whom a more complete skull exists, have
 > any teeth? I presume not, but I've found no reference to their presence or
 > lack thus far...

Since they are both included in the family Ornithomimidae, I
think it is safe to say both are toothless.  [And the lack of
teeth in Struthiomimus is quite definate, there are some very
good skulls around].

It is Harpymimus and Pelecanimimus that have teeth.

swf@elsegundoca.ncr.com         sarima@netcom.com

The peace of God be with you.