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RE: Bipedal apatosaurs and stegosaurs?

Nick Longrich writes;

>        And as for problems with balance- couldn't we make the same
>arguments about humans, which stand bipedally and which in males have the
>CG in the chest, and couldn't we argue the problems faced by the
>long-necked moas in keeped the head steady? And elephants and bears rear
>up, and possess none of the multiple specializations among the diplodocids
>that would make them so much better at it than Kodiak bears and Jumbo.
>I've never heard of a Kodiak bear falling down ("GROWL! I've fallen and I
>can't get up!" ;) )

Gotcha!  Actually, the CG in humans is located close to,and back from, the
navel, keeping it close enough to the hips to keep any additional
unstability (being bipedal is unstable enough) to a minimum.  Also, you
will note that the extant animal species that you note as rearing are those
that do so under special circumstances (rearing is a fighting stance in
bear, and a tree-toppling stance for elephants).  IF diplodicids did rear,
it would be under similarly unusual conditions.

Rob Meyerson
Orphan Vertebrate Paleontologist
"Can't I have a little bit of peril?"