RE: Altispinax diagnosis

[Tim Williams <twilliams_alpha@hotmail.com>]

Simon M. Clabby wrote:

> http://dml.cmnh.org/2002Jan/msg00267.html

Where to begin, where to begin...

According to this message, the "diagnosis" of _Altispinax_ is: "Tetanurae 
with dorsal spines up to five times the height of their respective centra; 
spines constricted just above the arch; pleurocoels shallow and short; 
centra with moderately flared ends; metatarsal IV with pronounced distal 
divergence relative to II; relative to metatarsals II and IV, III is larger 
and stouter; metatarsals II-IV with distinct distolateral and dorsomedial 
shoulders."

However, it cannot be established that _Megalosaurus oweni_ and 
_Acrocanthosaurus altispinax_ are synonyms.  The former is known from pedal 
material (BMNH 2559), the latter from distinctive vertebrae (BMNH R1828; 
inspiration for the name _Altispinax_), and there is no evidence that either 
belong to the same species.  I cannot vouch for the accuracy of the 
morphological description given above, but given its source I would advise 
to take it with a grain of salt and get a second opinion.

The message also says: "I reprinted this small paper, with minor revisions 
on 25 July 1994 (reprinted 10 February 1995), and a reprinting (slightly 
revised) on 16 August 1995."

Let's just say, the "small paper" probably did not appear in the sort of 
publication you'd find on a library shelf.  In other words, this foray into 
the taxonomy of _Altispinax_ was probably self-published and disseminated to 
a limited pool of individuals.

As for the taxonomic interpretations, the following is a farrago of 
nonsense:

     "Altispinax von Huene 1923 BMNH R1828 nomen conservandum
     = Becklespinax Olshevsky 1991 BMNH R1828 nomen rejectum
     = Valdoraptor Olshevsky 1991 BMNH 2559 nomen rejectum
     Altispinax lydekkerhueneorum Pickering 1990 BMNH R1828
     =   Megalosaurus oweni Lydekker 1889 BMNH 2559 nomen dubium
     = ?Acrocanthosaurus altispinax G.S. Paul 1988 nomen nudum
     = Becklespinax altispinax Olshevsky 1991 BMNH R1828 nomen rejectum et 
nudum
     = Valdoraptor oweni Olshevsky 1991 BMNH 2559 nomen rejectum et nudum"

A few comments:
1.  "Altispinax lydekkerhueneorum" is not a valid name.  It is no more valid 
than "Tyrannosaurus stanwinstonorum", "Allosaurus whitei", or any other 
dinosaur name that has sprung from the copious imagination of this author.
2. As I said, there is no evidence that _oweni_ and _altispinax_ are 
synonyms; this is pure speculation on the part of the author.
3. The issue of _Becklespinax_ versus _Altispinax_ as the valid name for _A. 
altispinax_ is still open to dispute.  There is no doubt that the valid 
species name is _altispinax_, proposed by Paul who erected the taxon 
_Acrocanthosaurus altispinax_ for BMNH R1828.  As this species clearly does 
not belong in _Acrocanthosaurus_, the question remains as to what the valid 
name of the genus is: _Altispinax_ or _Becklespinax_.  In his thesis, Rauhut 
put forward the view that _Altispinax_ has priority, since Huene intended 
the genus name to be attached to the distinctive vertebrae (BMNH R1828), not 
the teeth that are the type of _Megalosaurus dunkeri_ (to which BMNH R1828 
was once referred).  Olshevsky has a contrary opinion, and proposed the name 
_Becklespinax_ for this specimen.  Looks like a job for the ICZN...
4. I cannot fathom why the author calls _Acrocanthosaurus altispinax_ a 
_nomen nudum_ - unless he believes that the book _PDW_ does not satisfy ICZN 
rules for being considered a valid publication for the purposes of 
scientific nomenclature.  (How's that for irony?)
5. One cannot call a taxon a _nomen dubium_ AND refer it to another taxon.  
The term _nomen dubium_ is applied to any taxon that cannot be referred to 
another taxon, or have further material referred to it; the name is limited 
to the type material to which it was originally attached.
6. The terms _nomen rejectum_ and _nomen conservandum_ imply that a name was 
officially rejected or conserved, respectively.  An author cannot do this 
will-nilly.  In the example given above, the author in question is kidding 
himself.



Tim

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