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Re: Mickey Mouse Dinosaurs



In a message dated 97-05-28 05:24:15 EDT, jbois@umd5.umd.edu (John Bois)
writes:

<<  It is accepted (I'm assuming) that hadrosaurs
 were really slow.  So, the selective environment was completely
 different, i.e., not based on speed.  Therefore, we cannot assume
 that chases on the plain had a similar outcome.  It just is not
 analogous. >>

Were hadrosaurs thought to be really slow?  I honestly don't know.  I can't
recall hearing a theory one way or the other.  Most speed estimates I've read
dealt either with various ceratopsians (and the "can they, can't they" gallop
problem) and dromaesaur/ornithomimasaur (sp) types.  I would think that the
backbone and tail reinfocements on most hadrosaurs would serve to strengthen
the body at a run, more like a horse's rigid structure than a cheetah's
whiplash, hind feet before front feet sprint.  The implication to me would be
that they could manage a decent speed for a distance rather than a lightning
fast dash.

Here's a thought: from what I understand of the interlaced ligaments running
along hadrosaurs' spine and tail, the tail would be inflexible along its
entire length.  Now, with critters such as Deinonychus, the tail is flexible
where it joins the pelvis, theoretically allowing it to be used like a rudder
at speed for fast directional changes (again rather like a cheetah).  This
would, I assume, imply that the hadrosaur could not maneuver as quickly or
tightly as one of these smaller predators but perhaps had a limb proportion
conducive to a longer run if it could just manage to stay out of reach long
enough to tucker out a persuing predator.  Any thoughts?  Am I way off base
here?

I agree that we cannot draw one to one correlations between extant species
and dinosaur hunting habits and it becomes more complicated when we try to
parallel not only single species but whole interactive systems (such as the
lion/zebra, T-Rex/hadrosaur models).  However, we cannot IMO overlook the
value of using comparative anatomy to theorize.  We just need to remember
that in the absence of hard data we are doing just that...theorizing, not
concluding.