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Re: Sauropod cervical vertebrae



On Mon, 4 Nov 1996, Brian Curtice wrote:

>       I will have to check about Apatosaurus yahnapin and its upward 
> bend at the base.  Any chance you can give me the citation?  I do not 
> recall seeing it (the cervical character) in the Wyoming volume of last 
> year, but I do know he has quite a bit of the beast.

        I saw the thing at the Tate museum while McIntosh was there, and
my not-so-dependable memory seems to recall that a note was made of the
fact that one of the last dorsals, or first cervicals, whichever it was,
bore a prominent pair of bulges on the lower half of the forward face of
the vertebrae, and I thought he said something about this character being
similar to what is seen in Camarasaurus, although he couldn't recall last
time I asked him. 
        When I was talking about upward inclination of the spine, I just
meant that the long forelimbs make the back slope up, nothing very
technical. One would assume that this would impart at least a little
upward angle to the neck, even if it were held perfectly straight. 
 The articulation of the skull with the neck is such in
Diplodocus that the head would be carried at a 90 degree angle, according
to both Bakker and McIntosh, and the Camarasaurus one is much less acute.
Brachiosaurus, again, has the same sharp articulation. I'd guess it's neck
was more upright than that of Camarasaurus, but even modern giraffes have
a forward incline to the neck, so it may not have stuck quite straight up. 
        The cute thing they did- it was a talk presented at a conference
in Caspar in '94 though I don't have the ref. - was to look at the
semicircular canals. They work like a level, more or less, and you can
tell how the head was oriented just by tilting it until the semicircular
canals themselves are level. So we can be reasonably confident that
Diplodocus walked around with it's head carried proudly, nose pointing
forward, and it gives us an idea of the typical orientation of the neck. I
think this was done for both Camarasaurus and Diplodocus.

       -o
        |
        \          ,,iiiii,,,,,,,
         \-----+||||||||||||+++++++++----------------
                \\\\\\\ o     ''''''
                 /\\\   |
                 |      \
                /        \

        So this is kind of how a diplodocus might carry the head, probably
a little lower than that, but ASCI drawing is kinda hard. Notice that if
it rears up and extends the neck straight, the head is perfectly situated
- horizontal- to pluck twigs and needles (this was part of a speech
Bakker gave).


        nO\
           \
            \
             \
              +{{{{{{{{{{++++++++---------------
               \\\\\\\   o
                ///      |
                |        \
               /          \

Here's a Camarasaurus. The neck articulation probably wasn't even quite
this severe, but the head was at a bit of an angle to the neck, so the
neck might not have been held as high. 


     nO\
       |
       |
       \
        \
         \
          \
           \
            -++IIIIIIii
             \\\\\     i iiiii++++++--------
             o\\\\\    O                
             |///      |
             |         |
            /          \
           /            \

And brachiosaurus, maybe something like this, perhaps a shallower,
(again, I'm limited by the text characters) but the bit of neck at the
end would be likely near vertical. It sounds like we don't really know
about the cervical-dorsal transition, but it would seem logical that
it would bend the neck upward as it Camarasaurus. Notice how it can
reach high to pluck off tasty vowels and punctuation marks.

        nick L.