RE: bipedal lunges

["John Clavin (Digital)" <v-jclav@microsoft.com>]

While not discounting the possibility of triceratops being able to rise
briefly onto it's hind legs (after all the elephant can do it for
sustained periods), I don't see the advantage of it.
Where's the evolutionary advantage of all that head armour, if you're
going to get up and dance when you get in trouble. Much of triceratops
defence comes from threat, few would willingly face a charging one; and
the ability to rotate the head, combined with the power advantage of all
that muscle in the shoulders makes them dangerous at close quarters.
The only time I can see rising on the hind legs to be useful is in
driving the horns into an opponent at the end of a charge, when momentum
would likely force both protagonists to rise up.

> ----------
> From:         wa105@mead.anglia.ac.uk[SMTP:wa105@mead.anglia.ac.uk]
> Reply To:     wa105@mead.anglia.ac.uk
> Sent:         Monday, October 06, 1997 6:44 PM
> To:   dinosaur@usc.edu
> Cc:   wa105@mead.anglia.ac.uk
> Subject:      bipedal lunges
> 
> Toby wrote:
> 
> >You wrote:
> >>velocities. I like your idea of a brief charge. I've speculated and
> have
> >>developed some restorations of Triceratops going bipedal for a step
> or 
> >two at
> >>the culmination of a charge. I think most of their offensive
> activity was
> >>directed at each other, however.
> 
> >Dunno about a bipedal charge, but at least a bipedal lunge.  If the
> >principal defensive tactics were hers-based, it wouldn't do to have a
> >defender too far out of line.  But it still seems reasonable to have
> the
> >beast rock back and up on his hind-legs, thus reducing his moment of
> >inertia, then pivot, following the dodging tyrannosaur...
> 
> It doesn't seem reasonable to me, except in juveniles.  A typical 
> ceratopian had a heavy head and a long body, so its centre of gravity
> was 
> well forward of the hips.  I reckon it would have to raise itself
> almost 
> to the vertical to balance on its hind legs.  As it starts off sloping
> 
> downwards, it has to rotate through nearly 90 degrees.
> 
> And that's a long way for the front half of the animal to jump, if you
> see 
> what I mean.  As a rough rule of thumb, an athletic vertebrate can
> make a 
> standing jump of one metre, whatever its size.  (Not 2m, Mr
> Spielberg!)  
> And if we are generous enough to treat the front half of a ceratopian
> as 
> an athletic animal, that still doesn't get it nearly high enough.  A 
> hatchling ceratopian, certainly.  Adult Protoceratops, perhaps.  But 
> Triceratops?  No way.
> 
> >Plausible, anyway.  I have a little trouble believing a ceratopsan
> could
> >develop the speed, but it would't need too much.  Also, in a
> semi-erect
> >position, he'd get a lot of mechanical advantage on the pivot, just
> by
> >moving his head...
> 
> Sorry, I don't understand.  The pivot about what point?
> 
>                                                               Bill
>