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These are some comments on the interesting article on using computers to
simulate sauropods in the November Discover.
It certainly is correct that diplodocid necks were held sub-horizontal,
although it is not never possible to tell exactly what the angle was because
animals do not always habitually hold their necks in the nuetral posture
indicated by the cervical articulations. It is hardly likely that sauropods
wandered about with their heads at ground level, they would tend to be
surprised a lot. Nor were diplodocids regularly feeding on ground cover
despite their low neck carriage. This is one thing we know because Fiorillo
has SEM scanned their teeth, and they show very little of the grit wear that
occurs when animals eat dirty ground plants. In fact, the teeth show less
wear than those of camarasaurs, which were feeding somewhat lower because
they were shorter. Camarasaurs could barely reach the ground because their
short necks were so sharply flexed upwards at the neck base, and they could
probably rear up as well. That diplodocids kept their teeth so clean suggests
that they were feeding even higher on the well washed leaves of very tall
plants by rearing. I have compared the strength of the dorsal vertebrae and
find those of sauropods to be much larger and stronger than those giant
mammals of the same mass. Therefore, the former were overbuilt for being just
quadrupedal, and they should have been able to suspend their bodies from
their hips more easily than the latter.
The one thing I must disagree with is the sub-horizontal neck of
Brachiosaurus. The problem is that only the lower halves of the vertebra at
the neck-trunk juncture are known, the arches and the all important dorsal
articulations are missing. So I do not see how it is possible to restore the
posture of the neck base. I would not be at all surprised that a vertical
swan neck is not possible, but that brachiosaurs were so high shouldered, and
had true withers like giraffes, suggests their necks could be held at a steep
angle. Likewise, brachiosaurs should have been able to reach ground level in
order to drink, albeit just barely.
Now, what I would like to see are computer simulations of the daily
heat-storage/nocturnal cooling cycle of sauropods.