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Re: Theropod stance balance



1. I think they had lots of time to get as big as they
could. Experimental evidence indicates that
evolutionary changes in morphology can happen fairly
quickly when measured in generations.

2. The morphological refinements you mention indicate
a strong selective pressure for the re-allocation of
mass. I take this to mean that if Sue got bigger, the
mass re-allocation would need to continue. If Sue got
bigger, could she significantly increase bone
pneumaticization or neck recurve? I'm just guessing,
but her arms look so small they could be removed
entirely without affecting the center of mass. What
are the other morphological options here?
Bigger/longer tail is all I see. Maybe that would do
it, but wouldn't that slow her down to zero at some
point? Was Sue close to that point? I don't know,
that's for sure.

3. <<"Or possibly like ostriches get up after having
 fallen (anyone know how
 ostriches recover from a fall?).">>

Thats a great idea! I second the question. Anyone out
there happen to know?

4. << "3) then simply stand up." >>

LOL, you are obviously young and spry. I bet the head
came into play in moving the mass center over the
feet. As a guy who's been stranded in the woods with a
broken hip and a torn rotator cuff, I can tell you for
sure that it works...

I think falling down/over was a Darwinian level
problem for Sue, et. al., but I bet we agree that she
could definitely get up. Every time but once.

D

--- Phil Bigelow <bigelowp@juno.com> wrote:
> 
> 
> On Thu, 14 Apr 2005 09:29:22 -0700 (PDT) don ohmes
> <d_ohmes@yahoo.com>
> writes:
> 
> > So how the hell did Sue get up?
> 
> How the Hell Creek did Sue get up, you ask?  Here's
> one hypothesis: From
> a side-on-ground position: 1) tuck legs tightly
> under body, 2) roll onto
> belly, 3) then simply stand up.
> 
> Besides, chiropractors always tell people to "lift
> with your legs".
> 
> Or possibly like ostriches get up after having
> fallen (anyone know how
> ostriches recover from a fall?).
> 
> 
> BTW:  T. rex and ostriches are perfectly ballanced
> for two-legged travel.
>  T. rex had air-sacs in its skull that greatly
> reduced the head's weight,
> along with a recurved neck (moreso than on other
> theropods), and a long
> massive tail.  Ostriches, lacking a tail, have an
> even longer, more
> strongly recurved neck.  Recurving the neck shifts
> the center of gravity
> rearward.
> 
> I suspect that T. rex was nowhere near the
> theoretical limit for bipedal
> mass/size.  If the mass extinction hadn't occured, I
> can easily envision
> continued size inflation in evolving dinosaurs.  A
> 15-ton super
> Troodontid preying on a 20-ton ultra-triceratops
> would be quite a sight.
> 
> <pb>
> --
> 
> 
> 
>