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Re: Amazing Tendaguru and the most prolific localities in the world



> Date: Thu, 12 May 2005 14:42:29 -0500
> From: Tim Williams <twilliams_alpha@hotmail.com>
> 
>> The basic situation is that _no_ significant differences have been
>> demonstrated between the _B. altithorax_ and _B. brancai_ material.
> 
> Trouble is, the same could be said for much of the British
> brachiosaurid material as well.  _Pelorosaurus_ could just as easily
> be referred to _Brachiosaurus_.

(Well, vice versa, actually, since _Pelorosaurus_ predates
_Brachiosaurus_.)

Yes, I quite agree that the proliferation of non-diagnostic
brachiosaur names isn't helping anyone.  Here in the UK alone we have
Pelorosaurus, Oplosaurus, Eucamerotus, Ornithopsis, "Pleurocoelus
valdensis", perhaps Chondrosteosaurus and more.  Worse, various people
have attempted to synonymise various of these through the years, with
little success -- hence dumb combinations like "Ornithopsis
eucamerotus".  Naish et al. (2004) showed commendable restraint in not
naming the "Angloposeidon" vertebra MIWG.7306, which is actually much
better material than most of these names are based on.  Personally, I
would love to dump 'em all in Brachiosaurus and have done; problem is,
there is no reliable way to synonymise _any_ of them, since so little
of the material overlaps.  (And of course there is the matter of
priority.)

None of this really bears on the matter of generic separation of
_B. brancai_ from _B. altithorax_, though, since in the case of the
British brachiosaurs, there is an established status quo of too many
names that we just have to cope with, whereas with _Brachiosaurus_
proper, the status quo is the single generic name, and the burden of
proof lies (as I argued before) with those who wish to change matters.

By the way, I notice that Paul 1997 happily talks about
"_Brachiosaurus_ HMN SII" throughout, so Greg himself is not defending
the novel genus/subgenus.

>>> A brachiosaurid skull (USNM 5730) from the Morrison Formation,
>>> described by Carpenter and Tidwell (1998), has been referred to
>>> _Brachiosaurus_.
>> 
>> Only tentatively.  In point of fact, I think there is rather more
>> reason to think that this skull lies outside _Brachiosaurus_ than
>> that _B. brancai_ does.
> 
> At the current time, there is no evidence that more than one
> brachiosaurid species existed in the Morrison (AFAIK).

That's my understanding, too (unless anyone here knows different?)

> As you alluded to, the alleged brachiosaurid _Ultrasaurus_ is a
> synonym of _Supersaurus_, and the same is probably true of
> _Dystylosaurus_.

Ye-es.  I found Curtice and Stadtman's (2001) referral of
_Dystylosaurus_ to _Supersaurus_ less wholly convincing than Curtice
et al.'s (1996) similar job on _Ultrasaurus_; and it's worth
remembering that McIntosh (1990) described the _Dystylosaurus_ type
vertebra as "clearly brachiosaurian" (though I don't know whether he
changed his mind on that after reading the 2001 paper).

> USNM 5730 certainly belongs to a brachiosaurID, and you are right in
> saying that there is no positive evidence that it belongs to
> _Brachiosaurus_.  We will need more material to settle the question
> of whether USNM 5730 belongs to _B. altithorax_.

I agree that the skull is certainly brachiosaurid.  The thing is, the
only way we know that is be reference to _B. brancai_!  There is
_nothing_ to make anyone think that USNM 5730 is closely related to
FMNH 25107 except that both of them resemble Tendaguru brachiosaur
material.  So if you use USNM 5730 as "evidence" to remove _brancai_
from _Brachiosaurus_, then you cut off the very branch that USNM is
hanging from, and it could just as easily be (say) the head of
_Haplocanthosaurus_.  (Bear in mind that one of the many positions
_Haplo._ has been recovered in is as a basal Macronarian.)

> A reasonably complete _B. altithorax_ skeleton would really help.
> :-)

In _so_ many ways!  :-)

REFERENCES

Curtice, Brian D. and Kenneth L. Stadtman.  2001.  The demise of
_Dystylosaurus edwini_ and a revision of _Supersaurus vivianae_.
Western Association of Vertebrate Paleontologists and Mesa Southwest
Museum and Southwest Paleontologists Symposium, Bulletin, 8,
pp. 33-40.

Curtice, Brian D., Kenneth L. Stadtman and Linda J. Curtice.  1996.  A
reassessment of Ultrasauros Macintoshi (Jensen, 1985).  The
continental Jurassic M. Morales (Ed.)  Museum of Northern Arizona
Bulletin. 60:87-95.

McIntosh, John S.  1990.  Sauropoda.  in Weishampel, D.B., Dodson,
P. & Osmólska, H. (eds.), The Dinosauria.  University of California
Press.

Naish, Darren, David M. Martill, David Cooper and Kent A. Stevens.
2004.  Europe's largest dinosaur?  A giant brachiosaurid cervical
vertebra from the Wessex Formation (Early Cretaceous) of southern
England.  Cretaceous Research 2004: 1-9.

Paul, G. S.  1997.  Dinosaur models: the good, the bad, and using them
to estimate the mass of dinosaurs. Pp. 129­154 in D. L.  Wolberg,
E. Stump, and G. D. Rosenberg, eds. DinoFest International:
Proceedings of a Symposium Sponsored by Arizona State
University. Academy of Natural Sciences, Philadelphia.

 _/|_    ___________________________________________________________________
/o ) \/  Mike Taylor  <mike@miketaylor.org.uk>  http://www.miketaylor.org.uk
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