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Re: Jobaria and the Elephant Commit Suicide
On Fri, 12 Nov 1999, Matthew Bonnan wrote:
> Richard Travsky adds:
> >AN elephant merely provides a physical model for the behavior.
> Okay, but here we must be extremely careful. Despite all the functional
> stuff I could throw in here about elephant skeletons differing from
> sauropods (and you would all sigh and kill me), what elephant are talking
> about? African, Indian, what species, what geographic range? It is very
The jobaria web page specifies Sereno had access to a 20 year old African
elephant named Angus.
> easy to go from using an elephant as a useful yardstick to jumping to
> conclusions about specific behaviors. Just because Jobaria or other
> sauropods "look" like they're designed to rear up doesn't mean they did,
> whatever you compare them to.
The jobaria web page does give some insight into this. They calculate
the hind limbs could support three times the animal's weight.
> Richard Travsky adds further:
> >Don't forget, rearing up gives the impression of being larger. Many
> >animals do the equivalent - like raising fur or having a mane.
> Err, okay. But remember we are dealing with very huge animals here -- they
> are already big and weird. Why mess with them in the first place -- how
> much bigger and scarier do you need to be? You can step on or kick a
> dinosaur which comes close without the rearing, and some sauropods have what
> appear to be tail "weapons": whiplash in diplodocids, clubs in shunosaurs
> (unknown/unsure in other Chinese forms).
If a threat display deters a predator(s),then this is a cheap means of
survival. A lot cheaper than incurring wounds.
> While I will be the first to tell you sauropods have strong hands and limbs,
> the thought of all the weight crashing back down gives me the willies! I
Which would make it effective in defense. (Think of the noise alone!)
> don't care how much cartilage you stuff in there, I don't think the rearing
> and falling on your enemies thing would work too well. A more controlled
> descent, maybe, but then we'd need to look at what muscles and ligaments
> controlled that descent.
If the pelvic region could support three times the weight, then it seems
overbuilt. And with the center of gravity close to the pelvic region, a
controlled descent is not unimaginable. I think a more pertinent question
to ask is how was the pushoff accomplished.