RE: BRONTOSAURUS FOREVER! (and BIG MAMMAL TRAMPLES DEAD DINOSAUR)

["Williams, Tim" <TiJaWi@agron.iastate.edu>]

Garrison Hilliard wrote: 

>Screw it... I, Bob. and Gordon agree... it's Brontosaurus.

Oh well, that's it then.   :-)

Actually, the _Apatosaurus_ vs _Brontosaurus_ 'controversy' is not as
complicated as you might think, and boils down to three separate issues:

(1) Nomenclatural: _Apatosaurus_ was named before _Brontosaurus_ - but since
both genera were named by the same person (Marsh), do the laws of priority
apply?  The ICZN says yes.  Therefore _Apatosaurus_ gets the gig.

(2) Taxonomic I: Do _Brontosaurus excelsus_ (type species of _Brontosaurus_)
and _Apatosaurus ajax_ (type species of _Apatosaurus_) belong in the same
genus?  With one exception (see below), sauropod workers answer with a
resounding 'yes': the two species are so similar that they are certainly
congeneric, and perhaps even conspecific.  Thus, _Apatosaurus_ wins out as
the valid genus that contains both species.

(3) Taxonomic II: Is _Apatosaurus ajax_ a valid species?  _A. ajax_ is the
name-bearing species for _Apatosaurus_.  Hence, if the type specimen for _A.
ajax_ is shown to be non-diagnostic at the species level, then the name
_Apatosaurus_ gets thrown on the scrap heap as a _nomen dubium_ (or, more
properly, a _nomen vanum_).  As the next available name, _Brontosaurus_
would then become the valid name for this genus sans the _A. ajax_ holotype.
However, modern sauropod workers uphold the validity of _A. ajax_, despite
the immature nature of the type specimen.

Bakker has taken issue with both (1) and (2) - the former in the 1970's, and
the latter more recently (1998) on the basis of a distinctive sauropod skull
(not yet described) which Bakker mentioned as possibly referrable to _B.
excelsus_.



Tim


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Timothy J. Williams, Ph.D. 

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

Phone: 515 294 9233 
Fax:   515 294 9359