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Re: Sauropod cervical vertebrae



On Mon, 4 Nov 1996, Wayne Anderson wrote:

> Brian Curtice wrote:
> >     Being a HUGE fan of vertebrae...
> 
>         OK, sounds like Brian knows a lot about sauropod
> vertebrae. I'm sure others here do, too, so I'll ask a question I've
> been wondering about for some time now:
> 
>         In the book, "Dinosaurs: A Global View" (wonderful book!)
> Stephen Czerkas asserts that his observations indicate that sauropods
> could not lift their necks much beyond horizontal. While I don't claim
> to have knowledge to dispute this, this assertion seems to have been
> completely ingnored by the paleontological community.  Sauropods are
> still shown lifting their necks, and nobody even seems to have
> published a rebuttal.
> 
>         So we know what Mr. Czerkas says. What does everybody else say?

        In general, the diplodocid neck stuck straight out or down
slightly, although I seem to remember that Apatosaurus yahnapin had a neck
with an upward bend at the base. Camarasaurus has such a bend, and so the
neck did not stick straight out, but the relatively shallow angle on the
articulation between neck and skull mean that it probably didn't stick
straight up. Brachiosaurs have an upward inclination to the spine, an
upward bend at the base of the neck, and a nearly 90 degree angle between
head and spine (work on semicircular canals indicates that the heads were
held more or less horizontally) all indicate that the head was held very
high. I think Mamenchisaurus and many other Chinese sauropods also had the
upwards inclination. 
        From what I've heard, diplodocids also had an articulation of
about 90 degrees, most reconstructions ignore this. The head, again,
was carried horizontally, so while on all fours, the neck should have
craned outward and gently curved upward towards the end so that the
diplodocid muzzle would be pointed forward, not down. If Diplodocus
were to rear up, the head would be brought into a position similar to
what is seen in Brachiosaurus- a neck sticking upwards with the head
at a right angle to it at the top.
        There has been a lot of speculation as to whether the hearts would
allow this, but the bones seem to say that it did happen. Perhaps long
forelimbs and rearing were  ways to gain extra height without increasing
the load on the hearts and vascular systems too far- either rearing or
elongate forelimbs would increase the height of the head, but not increase
the distance between neck and heart. 
        I'd be interested if anyone knows how stegosaur necks articulate.