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Re: Refurbished Berlin Brachiosaurus Mount



Remes, Kristian writes:
 > Thanks a lot for the laud and comments, Mike.

My pleasure.  I'm not sure my sober comments fully conveyed the
gut-level excitement I felt when I saw those photos (however indequate
they may be).  I feel as though the new mount gives that beast back
its dignity :-)

 > Of course we chose an 'extreme' end in the spectrum of mounting
 > possibilities, but collaborating with Andreas Christian for a while
 > in the Sauropod Biology Research Group, I find his arguments pretty
 > convincing.

The problem is that, while Christian's argument is fairly convincing
in isolation (at least in its current refined form), so is Stevens and
Parrish's.  And so is Greg Paul's.  And so is Seymour and
Lillywhite's.  And so on :-)  So had it been me, I would have been
inclined (har!) to go for the safe option of an intermediate
position.  But I have to admit, I'm kind of glad that you didn't :-)

 > And even if the 'most neutral' pose of the neck would be 70° or
 > 60°, the pose shown in the new exhibtion would be still in the
 > range of motion _Brachiosaurus_ probably was capable of (Christian
 > and Dzemski 2007).

Possibly.  Since the posterior cervicals and anterior dorsals were
only ever known from centra, we just don't have the bones to tell us
either way.

 > The impression that C6-8 are curved backwards actually is an
 > optical illusion: they are oriented almost vertically, but still
 > inclined slightly cranially (about 85° to the horizontal plane). In
 > a word, the posture shown might not represent the most average of
 > all postures of the living animal, but I believe we present no
 > anatomical impossibilities.

OK.

 > By the way, with the new leg postures, the new orientation of the
 > scapulocoracoid, and this neck posture we managed to raise the head
 > of _Brachiosaurus_ to 13.27 m (adding about 1.5 m relative to the
 > old mount!). If the limbs were mounted in a vertical, standing
 > position (instead of the fast walking scene shown), another 20 or
 > 30 cm may be added.

Nice!  It does my heart good to see those forelimbs straightened.
It's still not clear to me how Janensch arrived at the funny-elbows
posture in the first place, as he's not very explicit in the 1950
skeletal-mount paper:

        In the forelimb the humerus, with its unmistakable
        s-shaped curvature in uncrushed condition, and with
        its proximal articular condyle clearly directed
        against the dorsal side of the bone, displays
        characters that are similar to the conditions of the
        humerus of lacertilians, crocodylians and Sphenodon,
        even if pronounced to a lesser degree, which, however,
        show that, in the type of motion of the upper arm, a
        component of lateral splaying was included. Thereby it
        appears to me that, in adaptation to the enormous
        load, an on the whole upright position of the humerus
        is the correct one, particularly since the distal
        articular end would only offer a very insignificant
        support surface in a horizontal position.

(page 99, translated.)  So far as I can make out from that, it may
simply have been a compromise between the horizontal-humerus posture
of its living relatives and the vertical-femur posture than Janensch
could see made anatomical and mechanical sense.

 > I hope many of you will find an opportunity to visit Berlin and
 > have a look at the new exhibition. I promise you won't regret! :-)

Oh I will.  :-)

 _/|_    ___________________________________________________________________
/o ) \/  Mike Taylor    <mike@indexdata.com>    http://www.miketaylor.org.uk
)_v__/\  The difference between C and Java is the difference between
         "int i" and "public static final transient volatile synchronized
         Integer theTemporaryLoopCounter".