RE: Ornithodiran phylogeny - a graphical approach

[Tim Williams <twilliams_alpha@hotmail.com>]

Mike Taylor wrote:

> It's funny how ubiquitous the name _Giraffatitan_ is on the Internet. As 
> far as I know, it's _never_ been used in the literature since Paul's (1988) 
> erection of the name as a subgenus and Olshevsky's
> (1991) raising of that name to generic level.

The name _Giraffatitan_ first appeared in the scientific journal _Hunteria_. 
 This meets ICZN standards (Article 8), so _Giraffatitan_ is a valid name.  
Although erected as a subgenus, my reading of the ICZN leads me to believe 
that it's a simple matter to bump a subgenus up to a genus.  So it will 
always be _Giraffatitan_ Paul 1988 irrespective of whether it's a new genus 
(as a binomen) or a subgenus of _Brachiosaurus_ (as a trinomen).  Promoting 
_Giraffatitan_ from subgenus to genus does not require a new description of 
the genus.  _Nomenclator Zoologicus_ treats _Giraffatitan_ as an available 
genus.  http://uio.mbl.edu/NomenclatorZoologicus/

Whether _Giraffatitan_ is a valid name in the *taxonomic* sense is another 
issue altogether.  I was willing to give _Giraffatitan_ a guernsey, but Mike 
convinced me it's _Brachiosaurus_.  However, if the _Brachiosaurus_ sp. 
skull described by Carpenter and Tidwell (1998) does belong to _B. 
altithorax_, it is different enough from the skull of _B. brancai_ that we 
have a good case for splitting the genus in two.

> In fact, it may even be that it's _never_ been used in peer-reviewed 
> literature, since Olshevsky (1991) was self-published and not AFAIK 
> reviewed, and I can't find anything in the Acknowledgements of Paul (1988) 
> thanking reviewers.

Although I wish it were otherwise, the ICZN does not mandate that a 
publication be peer-reviewed.  Olshevsky's work probably meets ICZN 
standards (Article 8.1), although his "Mesozoic Meanderings" is not ideal in 
this respect (Recommendation 8A: "Authors have a responsibility to ensure 
that new scientific names, nomenclatural acts, and information likely to 
affect nomenclature are made widely known. This responsibility is most 
easily discharged by publication in appropriate scientific journals..."

George Olshevsky (a.k.a. 'DinoGeorge') eschews peer review, but he is 
careful that his self-published, non-peer-reviewed writings meet the letter 
of the ICZN, if not the spirit.  Another maverick taxonomist named Stephan 
Pickering is more lax in this respect (failing to conform to the ICZN's 
already lenient standards), so his plethora of new dinosaur names 
("Newtonsaurus", "Tyrannosaurus stanwinstonorum", etc) can be confidently 
treated as invalid (nomina nuda).

As for ornithodiran phylogeny, based on what is known of _Sonorasaurus_, it 
is apparently morphologically identical to _Brachiosaurus_ (Curtice, 2000), 
so it can probably be referred to Brachiosauridae.

Cheers

Tim