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RE: Bipedal apatosaurs and stegosaurs?

Sorry for the delay - surgery.  But I feel I need to respond anyway.

From: Robert J Meyerson <meyersrt@uwec.edu> (Rob Meyerson)

 > >I am unsure of how great the loss of efficiency would be.
 > Assume for a moment that the CG of the diplodicids is located somewhere
 >  within the animals midsection (...)  In order to get into a rearing
 > posture, it would have to exert a tremendous force to get it's CG 
 > located directly over the hips,

No as much as you might think.  One of the main anatomical 
characteristics of the diplodocids is that the CG is placed well back
towards the hips to start with. A simple upward shift of the tail
might be sufficient to move the CG to the hip balance point.

 > >I think if they ingested large quantyities of foliage each time they
 > >reared up the loss would be *relatively* small.
 > ... or the really big ones, the amount of foliage
 >  reached by rearing would be so small as to make the posture
 > uneconomical (a 90' diplodicus reared up would have it's head at the
 > very tops of the pines, and there isn't that much foliage available
 > for consumption).

Don't think pines - think douglas fir, redwood, sequoia, sitka spruce
and do on.  These are all in the 200' to 300' height range.  Even a
rearing Diplodocus would *still* be well below the tops of these
forest behemoths. [This is a key point - it has even been suggested
that these groups evolved this enormous height to get beyond the
reach of sauropods].

swf@elsegundoca.ncr.com         sarima@ix.netcom.com

The peace of God be with you.