TALL SHOULDERS

[darren.naish@port.ac.uk]

Were brachiosaurs really tall at the shoulder? Nick (I think) wrote..

> ...is it not entirely certain that both _B._ and _G._ were as 
> high-shouldered as traditionally depicted?

And Tim replied...

> I think it's OK for _B. altithorax_, but I'm not sure about 
> _Giraffatitan_ or those poorly known Wealden "brachiosaurs" 
> (_Pelorosaurus_ etc).

Rumours have been kicking round for a while that the forelimb-
hindlimb disparity observed in _Brachiosaurus_ species might be (wait 
for it) due to the possibly chimaeric nature of the mounts. Most 
recently, John Martin and colleagues (1998) assert that all notions 
of limb disparity in brachiosaurs result from the Humboldt mount. 
Apparently, this is composite reconstruction with some plaster bits. 
Janensch (1914, 1929) does not, I believe, give enough measurements 
for the disparity to be demonstratable based on the two articulated 
specimens of _brancai_ he found. 

John et al. conclude provisionally that _brancai_ was higher in front 
that behind, but they suggest that _B(?). altithorax_ had front and 
hind limbs of equal length. Greg might disagree with this, as in his 
_Hunteria_ paper (and in subsequent articles), and as Tim explained 
in his email, he has shown how the angle of the sacral verts (called 
the anterodorsal inclination by Tim)  indicates a thorax that was 
held at a raised angle to the ground, rather than parallel to it as 
is reconstructed for most dinosaurs (Martinesque archaeopterygids 
notwithstanding.... these coelurosaurs clearly mimicked sifakas and 
hominines:)). However, if this sacral angle is true for titanosaurs, 
maybe the correlation doesn't work. I don't have any titanosaur 
figures to hand and don't known enough about sauropods to be 
competent. Going back to brachiosaurs (and assuming that they might 
be a clade)... WEALDEN TO THE RESCUE! The 'new' Isle of Wight 
brachiosaur, still in desperate need of formal publication, does have 
forelimb and hindlimb bones preserved. It may therefore reveal the 
limb proportions of the animal. 

Incidentally, the thing about archaeopterygids mimicking sifakas and 
hominines is not something I just made up - Martin actually wrote 
this in a recently published article (can't remember which one).

"He who is silent is understood to consent"

DARREN NAISH 
PALAEOBIOLOGY RESEARCH GROUP
School of Earth, Environmental & Physical Sciences
UNIVERSITY OF PORTSMOUTH
Burnaby Building
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