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Archaeoraptor v Microraptor

T. Mike Keesey wrote:

I remember asking this list a while ago what the difference between _nomen
dubium_ and _nomen vanum_ was. The upshot seemed to be that _nomen vanum_
didn't really mean much, and _nomen dubium_ should be used instead. Is
this right?

As I recall, "nomen dubium" refers to a name that is dubious for ANY reason. "Nomen vanum" refers specificaly to a name that is invalid because the type specimen was inadequate for diagnosis. There was an article in the _Journal of Vertebrate Paleontology_ which discussed this in depth. (If I'm wrong about this, then I invite corrections.)

At any rate, it seems that if _A. liaoningensis_ and _M. zhaoianus_ are
based on the same *individual*, what goes for one goes for the other.
Unless I'm mistaken, if Olson's designation is to be invalidated it must
be in some other fashion.

I'm not certain about this interpretation. _Archaeoraptor_ and _Microraptor_ may be based on the same *individual*, but one could say that they are based on different *specimens* (slab and counterslab). Slab and counterslabs of the same individual may or may not receive the same catalog number - in the case of _Microraptor_ they happened to be catalogued together. Many other individual fossils have counterslabs (e.g. _Scleromochlus taylori_, _Sinosauropteryx prima_) and it at the discretion of the museum (or whatever place the fossil is being housed) whether slab and counterslab are catalogued under the same number.

The other issue concerns what happens when earlier-named non-diagnostic material is shown to belong to a later-named specimen that is diagnostic. Does the name of the former take priority over the latter? This may have a precedent:


In this case, the crappy type specimen of _Manospondylus gigas_ might be one part of a more complete _T. rex_ specimen. Does this mean that this latter specimen must take the name _Manospondylus gigas_? If it does, then it means that we have a diagnostic specimen that carries the name _Manospondylus gigas_. This would further mean that the name _Manospondylus gigas_ would have priority over _T. rex_. My recollection of the discussion on the list that this story sparked regarded this proposition as absurd. The name _Manospondylus_ is attached to a non-diagnostic vertebra, and should be limited to this vertebra irrespective of whether this vertebra belongs to a more complete (and diagnostic) specimen of _T. rex_.

Similarly, in the _Archaeoraptor_ vs _Microraptor_ fracas, we have one *part* of the specimen (the tail vertebrae) carrying the name _Archaeoraptor_ and the whole specimen carrying the name _Microraptor_. If the tail vertebrae are non-diagnostic then, like _Manospondylus_, _Archaeoraptor_ can be put to bed as a _nomen dubium_.



Dr Timothy J. Williams

USDA/ARS Researcher
Agronomy Hall
Iowa State University
Ames IA 50014

Phone: 515 294 9233
Fax:   515 294 3163

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