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Re: bloated T. rex
>>>>2) have been due to having to rotate the thighs forward to keep the
>>>>feet under a forward-displaced center of gravity? (Squat-walking,
>>>>in other words.)
>>I didn't know whether to attach any significance to your lack of
>>comment on this one. My impression is that you were attributing the >T.
>rex's mobility impairment primarily to volumetric expansion >interfering
>with the action of the legs, or is that an >overextrapolation of your
>view? In other words, do you think putting >a couple of tons of meat in
>the stomach would have had any effect on >the rex's center of gravity?
>Just looking at a rex skeleton, (eg. the >one at
>http://tyrrell.magtech.ab.ca/tour/trex2.jpg ) it is hard for >me
>personally to imagine the stomach having been located far enough >back
>that this kind of weight would not have seriously tipped the rex
>>forward. I notice the balance problem in large carnivorous therapods
>>doesn't seem to particularly bother most people in the field, (take a
>>look at http://tyrrell.magtech.ab.ca/tour/alberto.html for what looks
>>to my inexperienced eyes to be a *serious* case of imbalance) and I >am
>trying to figure out why. I'm assuming the most likely explanation >is
>that the experts know something about this issue that I don't, and >I'm
>trying to find out what that is.
>A duck waddles because it is front heavy, I assume, but I think I've got
>it right. No counterbalancing tail, for instance. And while a rex would
>be front heavy with 1.5 tonnes of hot, fresh (or rotting) meat in front
>of it's hips, all he would have to do would rotate his body up in the
>front, the tail swinging back and forth behind like a tightrope-walker's
>balancing pole, and waddle forward, and this position may be a reason
>why the legs and hips are so broad and developed for muscle, to support
>the forward-heavy body. Normally, the center of gravity is right under
>the preacetabular bar of the ilium, but with all that extra weight put
>on, it moves forward about two feet (.45 meters) or so, and to
>compensate, the rex must move it back or he's ("she" in the case of Sue,
>we assume) in trouble of toppling. The duck waddle would be one of the
>few gaits allowable under such conditions, for it requires little
>femoral movement. The tibia and fibula support this as well, for they
>are very strait compared to the relatively curvaceous shins of smaller
>and lighter tyrannosaurs like *Albertosaurus* and *Daspletosaurus*, who
>would be less hindered by such balance-altering mass compsumption.
Doesn't John Hutchinson work on T. rex locomotion? This looks to be a
serious problem, if I recall the thread on toppling tyrranosaurids.