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Re: TALL SHOULDERS




Darren Naish wrote:

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.  [snip]
However, if this sacral angle is true for titanosaurs,
maybe the correlation doesn't work.

You're exactly right I think. This anterodorsal inclination of the sacrum is also seen in titanosauriform sauropods that have fore- and hindlimbs of around the same length (like titanosaurids, _Opisthocoelicaudia_). As I said in a previous posting, this meant that dorsal series must have curved a little between the shoulders and hips in these sauropods (I believe it was Salgado and Coria who proposed this).


Another reason why the upwardly and forwardly "tilted" sacrum may not be correlated with sloping of the thorax is that it's also seen in at least one camarasaurid: _Camarasaurus_ (originally _Cathetosaurus_) _lewisi_. To my knowledge, it is the only _Camara_ species to show this. This is wild speculation on my part, but _C. lewisi_ may be the closest outgroup to the Titanosauriformes. Brachiosaurs may have inherited this feature of the sacrum, and it may not be correlated with elongation of the forelimbs.


Tim

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