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RE: NY times article



There are many problems with the tail as weapon theory for diplodocid
sauropods.    The paper has the full  list, but here is the brief version.

The "whiplash" portion of the diplodocid tail is very thin and delicate.
The bones are 25 mm or less in diameter.   The last 2 meters of the tail
weigh 2 to 5 kg.  The joint surfaces of the final caudal vertebrae project
out, and would the first things to hit if the sauropod tail was used as a
weapon.

A weapon this thin and this light would have to be traveling very fast to
discourage any enemy that would actually threaten a sauropod.   But the
vertebrae and joints seem too delicate to withstand that.  Also, none of
them have been found injured.

If you compare with the tail clubs of ankylosaurs or the Chinese sauropod
Shunosarus, you see that the tail club is designed in a very different way.
Bony projections stick out to protect the joint surfaces, and the
construction is far more robust.

Iguanas and monitor lizards do use their tails this way, BUT their tails are
constructed very differently.

Finally, it is not at all obvious why sauropods would need a specific
defense mechanism.  They are HUGE.  Elephants and rhinos do not have any
"defense" mechanisms per se.  Rhino horns and elephant tusk are used almost
exclusively for display, and intraspecific fights.

Sauropods had much higher fecundity than elephants and rhinos (many eggs in
a clutch), so it is not at all obvious that we need to look for a defense
mechanism other than the fact that they were gigantic.  Allosaurs or other
predators might have eaten the young, and maybe some of the old and sick,
but those losses would be replaced by reproduction.

Finally, I should point out that in the paper we do not say that it is
impossible for the tails to have been used as weapons.  It is possible.  But
there are grave doubts.  The best way to use the tails as a weapon would be
if there was a tail extension beyond the last vertebrae made of tendon,
keratin etc which took the brunt of the impact forces.

Nathan

> -----Original Message-----
> From: Peter Von Sholly [SMTP:vonrex@gte.net]
> Sent: Wednesday, December 03, 1997 1:19 PM
> To:   Edward.Seidl@astramerck.com; dinosaur@usc.edu
> Subject:      Re: NY times article
> 
> I had an iguana that snapped its tail at our cats quite effectively- one
> can only imagine the power a sauropod tail would wield!  Even if it didn't
> crack like a whip, it would be able to deliver a tremendously powerful
> blow, I should think.  One of those across a theropod's nose (or anywhere
> else) might be all it would take to discourage unpleasant behavior for a
> lifetime.  Sauropods certainly would want some kind of defense mechanism,
> and those tails seem like good ones, (as you say, other reptiles do it).
> 
> ----------
> > From: Edward.Seidl@astramerck.com
> > To: dinosaur@usc.edu
> > Subject: Re: NY times article
> > Date: Wednesday, December 03, 1997 11:11 AM
> > 
> > 
> > 
> > >Myhrvold and Currie ... agreed with the paleontologists who now
> > >reject the idea that the sauropods regularly used their tails
> defensively. The animals >would probably have sustained as much
> > injury to their tails as they inflicted on >attackers.
> >