| An
elephant has a more difficult task in performing a hind leg stand
than Jobaria.
The elephants' center of mass is closer to the forelimbs than
the hindlimbs - exactly the opposite of Jobaria. Bone measurements
and footprint size confirm that Jobaria would have had
to move its center of mass only a short distance backward in order
to rear up on its hind legs.
But
could its main hind leg bone - the femur - withstand the bending
force generated by the hind leg stand? Or would it snap? Using
a computer-modeled sauropod and a bent-knee pose similar to
that of an elephant (shown in the illustration here), Jeff Ogradnik
was able to show that the bones of Jobaria were up to the task.
It would take a mass almost three times greater to snap
Jobaria's femur.
|
Illustration
of Jobaria rearing (by Dr. Sereno). The red dot shows the center
of mass, which is located directly above the hind feet.
|
Dr.
Sereno's research has led him to conclude sauropods like Jobaria were
agile, graceful, and much more flexible than paleontologists have
traditionally thought.
So
look at Jobaria in its rearing pose: you are seeing a snapshot
of how this dinosaur could move.
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