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RE: Altispinax diagnosis



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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