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

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

> Date: Wed, 11 May 2005 13:24:07 -0500
> From: "Tim Williams" <twilliams_alpha@hotmail.com>
> 
>> By the way, the name _Giraffatitan_ is not widely loved.
> 
> Well, I for one like _Giraffatitan_ (although perhaps "love" is too
> strong a word).

:-)

> Setting aside Greg Paul's evidence (I agree with Mike's
> interpretation of the dorsals), I think one can still build a strong
> case for separating the Morrison (_B. altithorax_) and Tendaguru
> (_B. brancai_) brachiosaur species into separate genera, and thereby
> supporting the validity of the genus _Giraffatitan_.

Bring it on, then!  :-)

The basic situation is that _no_ significant differences have been
demonstrated between the _B. altithorax_ and _B. brancai_ material.
Given that Janensch placed the latter in the same genus as the former,
the burden of proof lies with those who wish to remove it from that
genus.  As I have still yet to see any subtantiable claim that there
are differences, the status quo must prevail.  (That's not to say that
differences might not be described in the future; just that they
haven't been described _yet_.)

> 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.  The only reason to think the skull is
_B. altithorax_ at all is because it resembles that of _B. brancai_,
so if _brancai_ is removed from _B._, then the referral of the skull
collapses!  I also note that Carpenter and Tidwell are happy to use
_B. brancai_ consistently throughout their paper.

As a matter of fact, I don't really see that there is even any
justification, based on what's been published, to retain two different
_species_ of _Brachiosaurus_.  The bottom line is that there are
(roughly) two half-decent published specimens of _B._ worldwide, and
there is precious little evidence for separation.

> (3) I also prefer to keep the two species in separate genera due to
> biogeographical considerations.  To put _altithorax_ and _brancai_
> in the same genus tends to overstate the similarities between the
> Morrison and Tendaguru dinofaunas, which I don't think were as
> similar as traditionally thought.

Isn't this putting the cart before the horse?  If we are going to pay
more than lip-service to phylogenetic classification, we must surely
resist the temptation to name specimens on the basis of where they
were found.

(I suspect that Janensch's specific separation of _B. altithorax_ and
_B. brancai_ is probably on these very geographical grounds, but I
can't read German so I will have to rely of the charity of others to
tell me whether this is actually so.)

> In the same vein, the idea that _Allosaurus_, _Ceratosaurus_ and
> _Barosaurus_ were also shared by the Tendaguru and Morrison
> Formations is probably due to a combination of inadequate material
> and incorrect generic referrals [...] the Tendaguru "Barosaurus" is
> probably _Tornieria_.

The whole group of non-_brancai_ Tendaguru sauropods is pretty messy
taxonomically, and I am not sure any two workers mean quite the same
thing by all the names as each other.  At SVPCA 2004, Khristan Remes
claimed that "Barosaurus" _africanus_ is generically distinct from all
other sauropods, though closer to _Barosaurus_ than to anything else,
and advocated the use of the "available name" _Tornieria_ -- a re-use
which I am not sure clarifies matters.  I'm not aware that he's got a
paper out on this -- certianly nothing is referenced from this
home-page at
        http://userpage.fu-berlin.de/~palaeont/vertebrata/kristian_en.htm
I hope that when he publishes, he'll include a revision of _all_ those
problematic African sauropod names.

 _/|_    ___________________________________________________________________
/o ) \/  Mike Taylor  <mike@miketaylor.org.uk>  http://www.miketaylor.org.uk
)_v__/\  "If you can't convince them, confuse them" -- Harry S. Truman.

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