Re: Amargasaurus...

["T. Mike Keesey" <tmk@dinosauricon.com>]

On Thu, 26 Apr 2001, Steve  Brusatte wrote:

> Oh, you're absolutely right.  Amargasaurus was something like 11-12
> meters long-very small as far as sauropods go...especially considering
> that predators such as Giganotosaurus and the new Argentine guy (when
> is it going to be named) likely targeted it.
>
> However, I still believe that 12 meters long is big!

Large _Carcharodontosaurinae_ would have towered over it, though.
(cf. the Luis Rey pic I posted a link to)

> And, I do agree that the spines do seem gracile.  There is a really
> good photo on the Dinosauricon at
> http://dinosauricon.com/images/amargasaurus-bs.html Even if these
> spikes were more robust and could inflict damage,

It still seems to me that they are large enough to ward off bites,
especially if they had sharp keratinous sheaths.

> the predator could simply bite the side or underside of the neck and
> get right past them.

It couldn't bite the side more than a nip unless it opened its mouth wide
enough to encompass the spines, and then we're back to square one. Biting
from the underside would work, but look at it this way: what's better,
protection from the top and sides, or no protection at all? In an
environment where there are such tall predatory theropods a sauropod with
neck spines is going to have some kind of advantage over one without them.

> If Amargasaurus was to truly evolve a protective mechanism for its
> neck, I would think that a nice, thick set of armor would be much
> better and much more protective.

Too bad _Amargasaurus_ didn't think of that....
Of course, this may be one reason why titanosaurs outlasted
dicraeosaurids.

> These spines seem very ostentatious...and rarely are "showy" objects
> used for defense purposes (at least exclusively).

That's possible, too. I can't imagine that they didn't have some role in
protecting the neck, one of the most vulnerable parts of any
sauropodomorph.

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