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

[Mike Taylor <mike@miketaylor.org.uk>]

> Date: Fri, 13 May 2005 09:28:38 -0500
> From: Tim Williams <twilliams_alpha@hotmail.com>
> 
>>> 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?)
> 
> I was informed (off-list) by a former DML member that another
> Morrison brachiosaurid is known, but not yet described.  He says
> that a "nearly complete new brachiosaurid" was "collected by the
> University of Kansas and then sent to Korea" where it is being
> studied by Larry Martin ("yea, the bird guy").

I assume this is the same specimen that's mentioned in passing in
Bonnan and Wedel 2004?  I quote from page 14:

        Finally, _Brachiosaurus_ is apparently present in the
        University of Kansas quarry in Weston Co., Wyoming,
        although the find has only been reported in popular
        articles to date (e.g., Sherman 2003; see Foster 2003
        for further information on the quarry).
        _Brachiosaurus_ material reportedly present in the
        quarry includes a nearly complete skeleton and a pes
        of a second individual (Sherman, 2003).

I didn't know it had gone to Korea!  Yow.  Where did you hear that?

>> 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_;
> 
> I'm with you on that one.  Still, from memory the taphonomy supports
> Curtice and Stadtman's (2001) referral.

Inasmuch as this supposed _Supersaurus_ dorsal was found slap bang
between the two _Supersaurus_ scapulae, yes :-)

Actually, going back and revisiting my notes on the _Dystylosaurus_
referral -- ironically from one year ago, to the day -- I am now much
less convinced than I was then by my argument.  For example, at that
time, I thought that the centrum's proportions in anterior view (width
about 1.3 time height) seemed like a good brachiosaur character; not
so.  Still, its spine is extremely puzzling, whatever it is.

> Firstly, the combination of features seen in the skull is consistent
> with a primitive titanosauriform.  I very much doubt that the skull
> belongs to a diplodocoid, or even a basal macronarian.

Remind me, how much material do we have that shows us the differences
between the skulls of basal Macronarians and basal Titanosauriforms?
Not much.  From a quick re-skim of Salgado and Calvo 1997, in fact, I
am tempted to say "none at all".

(Not that I am seriously arguing that Ken's sauropod skull is
_Haplocanthosaurus_, to be clear!  All I'm saying that we wouldn't
know _what_ it is were it not for comparisons with _B. brancai_.)

> [...] which is consistent with the proportionately longer dorsal
> vertebral column (relative to the humerus or femur) of _altithorax_
> compared to _brancai_; this longer trunk is a primitive trait for
> _altithorax_.

Woah!  _What_ longer dorsal column?  There is no complete dorsal
column of _either_ _Brachiosaurus_ species in existence.  (Well, there
are probably a couple of unpublished ones and no doubt several in the
ground :-)

The best _B. altithorax_ dorsal sequence is still that of the type
specimen, consisting of the seven most posterior dorsals in
articulation, and nothing further forward; and the best _B. brancai_
dorsal sequence is probably that of HMN SII, consisting of D1, D2 and
the anterior part of D3, all lost; plus D4, D7 and a D10/D11 pair --
but of course those position assignments are pretty much guesswork,
especially as you get further back.  (The Tendaguru brachiosaur
excavated by the British in 1930, probably _B. brancai_, _may_ have
had a sequence of eleven, twelve or maybe even thirteen dorsals, based
on Migeod's (1931) comments; but most of that specimen is still in its
jackets.)

(And it occurs to me as I write this that, given the relatively small
number of cervicals in _B. brancai_, it wouldn't be a total surprise
to find that it had a goodly complement of dorsals.)

> They cite Paul (1988) for this character.  So Mike (or anybody
> else), I can't locate my copy of Paul (1988), so is this last
> character still considered a valid way of distinguishing
> _altithorax_ from _brancai_?

I don't think anyone has published a discussion following up on this,
so the character has never been refuted in print.  But I am not
convinced that it was ever valid, given the paucity of available
material.

REFERENCES

Bonnan, Matthew F. and Mathew J. Wedel.  2004.  First occurrence of
Brachiosaurus (Dinosauria: Sauropoda) from the Upper Jurassic Morrison
Formation of Oklahoma.  PaleoBios 24(2): 13-21.

Migeod, F. W. H.  1931.  British Museum East Africa Expedition:
Account of the work done in 1930.  Annals and Magazine of Natural
History 3(19), pp 87-103.

Salgado, Leonardo, and Jorge Orlando Calvo.  1997.  Evolution of
titanosaurid sauropods. II: the cranial evidence.  Ameghiniana
34:33-48.

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