Re: bipedal lunges

[Chris Campbell <sankarah@ou.edu>]

Rob Meyerson wrote:
> 
> >I'd have to say that these charges being fatal is pretty much the
> >general idea behind them.
> >But I wasn't thinking of charges being used against other Triceratops',
> >more as a defence against predators.
> 
> Usually, features located on the head (horns, antlers, etc) are used 
> against the owners own species.  

This depends on the species in question.  Large bovids (cattle, bison,
buffalo) very definitely use their horns in defense.  Deer will as well,
but it's a secondary function and often an act of desperation.  Same
with antelope.  

>Features on the tail (quills, spikes, etc.) are the ones used against 
>predators, to aid in an escape.  

This is hard to say, as we don't really have any large herbivores with
spikes, clubs, or whatever on the tail today.  For all we know, these
things might have been intraspecific.  Look at the way giraffes smack
one another with their heads; ankylosaurs may have just pounded one
another into submission with their tails (assuming the tails had that
range of motion, anyway).  I doubt this was the case, but we can't rule
anything out a priori.

>Ceratopian horns are most likely for intraspecies combat.

I strongly think this depends on the species.  _Torosaurus_ and
_Triceratops_, in particular, have horn arrangements which are perfect
for use against predators and relatively poor for use against
conspecifics.  The reverse is true in most other horned Ceratopian
species; the horns are arranged well for intraspecific combat and very
poorly for purely defensive purposes.
 
> >I fully agree that for intra
> >species fights, mating displays and such like, close quarters "horn
> >wrestling" is likely. The deer analogy here is quite apt.
> >However that cannot be their entire purpose, because then why would they
> >be pointed, and why have a shield behind them?
> 
> As I commented in another posting, the frill and horns developed 
> independantly 
> from each other.  In is in the more developed ceratopians that these two 
> features 
> combined into, what I call, a unison bluff display (waving the frill and 
> horns 
> about would be an effective deterrant).  

Not really; some of the most impressive bluff displays can be found
among the short-frilled ceratopians (particularly _Styracosaurus_), who
had very little cranial horn development at all.  The obvious exception
to this rule is _Triceratops_, a ceratopian with an utterly unremarkable
frill who had the most spectacular horn development of all the
ceratopians.  On the long-frilled side we have typically small horns
whose size, with the exception of _Torosaurus_, doesn't change much with
frill size.  

So, basically, the only ceratopians with really big honkin' horns were
_Triceratops_ and _Torosaurus_, one of whom had a long frill while the
other had a short frill.  The other short frills either had no horns or
only had nasal horns (though some developed impressive racks, as it
were, e.g. _Styracosaurus_), and the other long-frills had horns what
were pretty much the same size, relatively speaking.  So the frills may
have been used as bluff devices, but we don't really see any trend which
would indicate this use increased over time as you suggest.

>In the protoceratopians and chasmosaurine ceratopians, the frill is pretty 
>pathetic as a shield; the large fenestra in the frills would seriously 
>weaken their defensive abilities.

This is true in some but not all of the chasmosaurine ceratopians; see
_Arrhinoceratops_ and _Anchiceratops_ for good examples (the former had
a quite solid frill).  _Protoceratops_ might have just used the frill to
guard against things like small dromaeosaurs, and against their claws
and teeth the frill would have worked just fine (see the fighting dinos;
the _Velociraptor_ was getting his butt kicked, though he apparently
gave as good as he got).
 
> >If you consider the speed and momentum available to a charging
> >triceratops, and a forward facing set of weapons, I think this points
> >very clearly to the charge being used as a tactic.

I used to agree, but if you look at the skulls you'll see this is only
the case in a couple of specimens.  It wouldn't work for most of them
just because of the length and/or shape/position of the horns.
 
Chris