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At 2:21 PM 9/20/95, Cunningham, Betty wrote:
>     >A large tail could make humping locomotion a bit difficult.
>     When killer whales go up onto iceflows after seals, and when
>     performing at Sea World, etc, what do you call the surface locomotion
>     they do that has them pumping up and down with their front ends as
>     they lurch forwards?  Is this also "humping" and wouldn't the fact
>     that Orca do this today in the wild falsify the above statement?
>     -Betty Cunningham

        Nope.  In both examples, Orcas never fully leave the water, and the
desribed behavior usually occurs on an inclined surface (take a look at the
special shelves in the Orca tanks, the next time you're at Sea World.  When
an Orca smacks into a chunk of ice, the result is that the ice is usually
angled under the whale's weight, and the tasty tidbits slide down to be
eaten.  While Orcas are able to "slide" up onto a surface, their forelimbs
could never support their weight, which is what occurs in pinniped humping.
Its not the same thing.  Early archaeocetes have similar forelimb
structures to pinnipeds, but their axial skeletons are pretty different.
Take a look at a seal: its main body mass is toward the head, and the
posterior region is pretty small in comparison.  Archaeocetes have elongate
bodies, very different pelvic girdles, and those tails.  I've got no clues
as to have the early archaeocetes moved on land, but it must've been pretty

All My Best,

Jason J. Head
V.P. graduate student
Dept. of Geological Sciences
Southern Methodist University
Dallas, Tx. 75275