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Re: Australodocus a titanosauriform and other new papers



On 12 July 2011 05:34, Tim Williams <tijawi@gmail.com> wrote:
>> John A. Whitlock (2011)
>> Re-evaluation of Australodocus bohetii, a putative diplodocoid sauropod
>> from the Tendaguru Formation of Tanzania, with comment on Late Jurassic
>> sauropod faunal diversity and palaeoecology.
>> Palaeogeography, Palaeoclimatology, Palaeoecology (advance online
>> publication)
>> doi:10.1016/j.palaeo.2011.07.001
>> http://www.sciencedirect.com/science/article/pii/S0031018211003579
>
> I'm not qualified to comment on the merits of the assignment of the
> cervicals named  _Australodocus_ to basal Titanosauriformes... but two
> things come to mind:
>
> Firstly, if _Australodocus_ is *not* a diplodocoid, does that mean
> that all the diplodocid material from Tendaguru can be returned back
> to _Tornieria_?

IF Whitlock is correct about Australodocus (and I don't have an
opinion about that yet because I prefer to wait for the paper to be
actually published than to read an unedited and unformatted
manuscript) then, yes, Tornieria will be -- for now -- the only
recognised diplodocid from Tendaguru.  (Although consistency with his
usual taxonomic practice would require Whitlock to fold even that back
into Barosaurus, following "tradition".)

> Secondly, I'm bewildered by Whitlock's reasoning for sinking
> _Giraffatitan_ into _Brachiosaurus_:

Oh, jeez, don't get me started on this, uh, let's call it a courageous
manoeuvre.

>     Although numerous morphological differences exist between B.
>     altithorax and B. brancai, the genus Brachiosaurus has never been
> demonstrated
>     to be polyphyletic. Failing that, without a recognized criterion
> for determining
>     whether two taxa are either distinct palaeospecies or palaeogenera based 
> on
>     morphology alone, the decision to replace an existing name (in this case,
>     Brachiosaurus) with a different one (Giraffatitan) must be seen as 
> somewhat
>     arbitrary.

The moment someone does a phylogenetic analysis that includes more
putative brachiosaurids than Brachiosaurus and Giraffatitan, and that
has some resolution, then B. and G. WILL be split.  There is no
question about it -- as I said in the 2009 paper, they differ in
almost Every. Single. Bone.  They are not similar animals.  They're
just not.  Already we have Ksepka's (2010) paper --
        http://digitallibrary.amnh.org/dspace/handle/2246/6087
which found Brachiosaurus, Giraffatitan, Cedarosaurus, Paluxysaurus
and Abydosaurus in a polytomy.  (It would be intresting to see whether
that analysis could get more resolution by host-hoc deleting taxa.)
Until then, I guess Whitlock refers to all five of those taxa as
"Brachiosaurus" species.

In the mean time, the scientific staff of the Humboldt Museum in
Berlin, where all the Giraffatitan material resides, have been calling
it by its proper name for some time -- see for example the recent
paper on nutrient foramen size by  Seymour, Smith, White, Henderson
and Schwarz-Wings.

I really don't know what Wilson (in Chure et al. 2010) and now
Whitlock are trying to achieve by hanging on to the discredited notion
that the German brachiosaur is Brachiosaurus, but it's a notion that
cannot possibly endure.  That game is over.  The ONLY reason to keep
talking about "Brachiosaurus" brancai is inertia.

-- Mike, trying to be a polite as possible.


(And with that, I will retire as gracefully as I can from the
discussion.  I have nothing left to say to Jaime that I haven't
already said hundred times.)