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RE: galloping sauropods?




        -----Original Message-----
        From:   Michael Teuton [SMTP:tons@ccs.logicsouth.com]
        Sent:   Monday, October 26, 1998 10:35 AM
        To:     ottscay@uwyo.edu
        Cc:     Christopher Srnka; List Dinosaur
        Subject:        Re: galloping sauropods?



        Scott A Hartman wrote:

        > >>>I've seen some depictions of Brachiosaurs in a giraffe-like
gallop, <<<


        Cartilage does absorb some shock but its primary purpose is to allow
the joint
        to go through its range of motion with ease and lack of discomfort.
Bone on
        bone is not comfortable or efficient.  Joint fluid acts as a
hydraulic
        dampener .  Fluid does not compress in this situation.  Finally, the
ligaments
        or joint capsule and surrounding musculature absorbs energy as well.

        Well, as a physicist WITH lifelong arthritis, I guess I know quite a
bit about joints
        (much of it from PAINFUL, PERSONAL experience!) :-)    I have been
told by orthopedic surgeons that cartilage is equally a shock absorber & a
buffer between bone on bone.
        Of course, that's with a homo sapien, but I would suspect the
function is much the same in other animals.  The sinovial fluid DOES act as
a damper, as well & lubricates the joint & surrounding soft tissue much like
the lubricant in your car.    As a general rule, the bigger the joint, the
more cartilage & fluid there is in a joint.  

        So the energy of impact would be dampened by the entire joint and
surrounding
        tissues.  If there are any structures above the joint, I think some
of the
        energy would be transmitted there as well.  Is this correct physics
buffs and
        locomotion experts???

        With the legs held straight (no or little knee flexion) the force is
transmitted into the hip structure AND the  glutius maximus AND into the
lower back.  Animals who stand with their legs straight, therefore have a
robust hip structure & powerful "butt" muscles.  That is the largest muscle
in the human body (upper thighs are the second biggest).   Flexing the knees
transmits more of the force into the powerful butt & leg muscles & less into
the lower back.

        As a matter of conjecture, my opinion is they moved much like
elephants, but
        we don't know this.  How fast could they run?  Fast enough to evolve
        successfully over millions of years.


        Michael Teuton

        Elephants LOOK like a good model for saurapod movement.  Despite
being straight-legged
        Walkers/runners, we humans are bipedal (YES: EVEN IN TEXAS!) .
Top human speed is > 20 miles per hour (in a sprint), with ~ 10 miles per
hour for long distance running.  As far as elephant speeds, I KNOW I've seen
the numbers, but can't call them to memory ATT.
        I do recall be surprised that (whatever value it is) was that fast.
Still, I'll bet someone on the list knows precisely.

        Dwight