Re: Re[2]: new boook on functional morphology

[ornstn@inforamp.net (Ronald Orenstein)]

>        However, as shown with sumos (;]), the heavier an animal is, the 
>     resting posture is closer to the posture of it's regular gait (or, 
>     conversely, the regular gait is not that different from it's resting 
>     posture), since this tends to save energy when starting and stopping 
>     motion.  So a ceratopian dinosaur would probably not do lots of weight 
>     shifting in order to go from it's standing posture to it's walking 
>     posture, as that tends to be more energy expensive. >     
>     -Betty

This is valid, but it is not exactly what I meant.  Say, for example, that a
sprawled posture gave greater leverage in head-shoving matches.  This is
hardly a resting posture - in fact such contests might have placed greater
stresses and torques on the pectoral girdle than any other activity, and as
they may have been crucial to mate choice (say) selection may have acted to
maximise ability to win such contests in the evolution of the pectoral
girdle over such other activities as resting or walking.  Thus a rarely-used
but crucial posture could have had a greater effect on the evolution of
these structures than much more commonly-used ones.

Of course this is WILD speculation assuming all sorts of things about what
these critters were doing - something I don't normally like (or feel
competent) to do - but I offer it only as a possible way to reconcile J&O's
findings (which, I repeat, I have not read and cannot comment on critically)
with the trackway evidence.
--
Ronald I. Orenstein                           Phone: (905) 820-7886 (home)
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