Re: new boook on functional morphology

[Stan Friesen <swf@ElSegundoCA.ATTGIS.COM>]

From: JCMcL <darwincr@laplaza.taos.nm.us>
 > > That aside, it is still true the main use of the horns was probably
 > > contests *within* the species.  Even well-armed herbivores prefer
 > > to run away from predators rather than fight.
 > 
 > Just a thought.  I have less confidence than Stan in my understanding of 
 > the ceratopsian behavior patterns, but know that they shared their world 
 > with many predators that could easily outrun them.

I would not say I am that certain.  I just find the old, traditional
over-emphasis on fighting predators so powerful that I want to make
sure of countering it.

 > A formidable and aggressive familial defense, a prickly ring of adults, 
 > seems fairly likely to me.

To me, too - when overtaken with young present.  Indeed, even antelope
that do not use this group defense will stand and fight to protect
the young.  I have seen film of a single wildebeest female charging
hyenas that were attacking its calf.  However, that same wildebeest
would run from the hyenas if the calf were not present.

And of course, once overtaken and attacked, a prey animal will use
everything it has to escape.  This includes horns.

Most predators do not go into all-out chase mode until they have
a fairly good chance of success.  This means that a prey animal that
runs early may not even be chased.

A general rule in biology is: do things the cheap way if possible.

What I am opposed to is the old picture of a solitary Triceratops
having a duel with a Tyrannosaurus.  I doubt that a Tyrannosaurus
would confront a healthy adult Triceratops from the front under
normal circumstance.  If the T. rex attacked at all, it would do
so from the side, and then back off if the attack failed. For instance
in the film of the wildebeest protecting its calf, the hyenas stayed
well clear of mama's front end.  They accomplished their goal by
cooperation - while mama was off chasing one hyena, another one
or two would attack the calf.

The simple fact is that, except when hunger threatens to interfere
with reproduction, predators prefer not to even *risk* injury. And,
given a choice between standing and fighting (and risking injury)
and running away, a potential prey will choose running away - unless
the reproductive cost of running is higher than the risk of injury.



Note, in one reference I have a case is made that dinosaurs, even
the large ones. were r-selected, rather than K-selected like large
mammals.  If this is really so, than it may never have been the case
that protecting young was economically viable (individual young are
not as valuable to a r-selected animal, and so are less often protected).

swf@elsegundoca.attgis.com              sarima@netcom.com

The peace of God be with you.