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Re: cause of Gigantism in sauropods



On 10 February 2011 17:31, Denver Fowler <df9465@yahoo.co.uk> wrote:
> ----- Original Message ----
>
> From: Mike Taylor <mike@indexdata.com>
>>> How many sauropod neck specimens show bite marks?
>>What an interesting question!
>>As far as I KNOW, the answer is: none.  At least, I don't know of any
> publication describing such a thing.
>>But that certainly doesn't mean they're not out there.  The problem
> is: how would you tell?  Sauropod cervicals are perhaps the most
> fragile of all fossils, due to the combination of large size, complex
> morphology and delicate construction.  Distortion is almost
> inevitable, and indeed I've made the point on SV-POW! --
>
> http://svpow.wordpress.com/2009/05/30/range-of-motion-in-intervertebral-joints-why-we-dont-trust-dinomorph/
>
> that it's questionable whether there are ANY complete, undamaged and
> undistorted sauropod cervicals known to science.
>>Against that backdrop, unequivocal bite marks are going to be difficult to
> find.
>
> Mmm... I don't see distortion as a major hindrance in recgonising toothmarks.
> Surface cracking is more of a problem.

True.  But because the bone is so delicate, much distortion results in
cracking anyway.

> And why would you expect toothmarks from a kill anyway? Most (if not all) of 
> the
> toothmarks I have observed (on other dinosaur taxa) are much more likely to be
> from carcass processing.

Indeed.  The only way you could KNOW that a toothmark on a sauropod
cervical was from a bite inflicted on a live animal would be if the
mark was healing.  And since that would show that the prey animal
survived, it would not much help in demonstrating that, as some on
this list have asserted, theropods could take sauropods down with a
single bite.

> I have mental picture of a big theropod biting into the neck of a sauropod,
> piercing one of the air sacs, and the sauropod deflating like a giant balloon.

I've heard this idea from a couple of places.  I don't see it at all
-- that would happen only if the pneumatic diverticula were
pressurised.  There is no reason at all to think that was the case,
and plenty of reasons for thinking it was not -- though sadly all I
can cite to back up that assertion at this stage is "in prep", and I
don't want to scoop myself on the DML :-)  I think a much bigger
problem if a theropod bite penetrated a penumatic diverticulum would
be infection.

-- Mike.