Re: cause of Gigantism in sauropods

[Don Ohmes <d_ohmes@yahoo.com>]

On 2/10/2011 12:34 PM, Raptorial Talon wrote:

> 1. How effective were large theropod teeth at sinking into a good
> 10-20 cm of leathery skin?

Given a neck diameter of 1m, that implies the neck could be as much as 
40% skin -- even more where it is smaller.

> 2. How much torque would be required to snap a large theropod's teeth
> right out of its jaws?

What effect would such action have on the extremely high-pressure veins 
and arteries that presumably lay somewhere between the "vertebral anvil" 
and the knife-like teeth? Why would the theropod not simply let go, and 
wait a bit. Any bleeding must have been dramatic. Plus, their teeth grew 
back.

> 3. How much torque could a flailing sauropod neck generate with a
> single pull or twist? (Toward the base at least, since that's the part
> closest to the ground in a big sauropod.)
>
> This posits a lot of (currently) unanswerable questions, I know, but I
> think the volumetric scaling of the inertia/momentum involved here
> needs to be considered more closely. It seems to me that a ton or two
> of collagen-fortified sauropod neck would be a rather nasty implement
> for causing injuries to the jaws (wrenching), brain (concussion), or
> even entire body, if they were to knock a multiton theropod right to
> the ground.

Still sounds less dangerous and less likely than falling while running 
fulltilt after smaller faster prey. Especially given that simply 
harassing a giant sauropod for 2 or 3 days might get you a huge happy 
meal w/out a bite fired, so to speak.

I note in passing that people who have land w/ "steep terrain" are NOT 
advised to take up ostrich farming -- the risk of injurious falls is 
considered to be high. That said, I have no idea what exactly is meant 
by "steep" in this case, or whether the advice is universal or even 
knowledgeable.

Asking ostrich farmers (about 5, iirc) whether the birds take falls 
brings a "yes" -- mostly adolescents "cutting the fool", according to 
one. Ditto emus, but there the issue seems to avoidance of the farmer.

There is a paper to be done there, I think.

That said, I am also extremely skeptical of neck-as-weapon scenarios -- 
the small and fragile head was out there on the end of all those highly 
pneumaticized vertebrae and critical fluid/electrical transmission systems!

a) Given a hold near the base, the "head velocities" implied by any 
movement or flailing that could exert force on the base of an 8m-10m 
neck are pretty damned extreme. This could drastically affect 
circulation and balance -- and any collision (with a tree branch, the 
ground, or even the theropod) would be severe.

Rapid head swings were unlikely to part of the repertoire -- pi*10m =~ 
31.4 m -- so roughly 10m/sec, given 3 seconds to make a half circle... 
any slower, even a giant biped could dodge the blow. The sauropod has 
serious momentum issues should it miss. It just does not seem workable 
in any sense other than a straight pull back with the main body, and 
what good would that do?

b) Given a hold anywhere near the head, the mechanical advantage is such 
that the force required to move a biting theropod would be horrendous -- 
the neckskin distal to the torso could only be so thick, and nerves 
might be crushed by the bite -- talk about "command and control center" 
disruption...

> Size alone doesn't mean everything, although it certainly counts;
> armament and temperament count for a lot too. I've seen the footage of
> lions taking down 4+ ton elephants, but not once have I heard tell of
> lions taking on rhinos, not even the small 1.5-ton black rhinos, which
> are known to nap in the open in the middle of lion territory.

Yes.

> That and juveniles are always a tasty snack.

If you can find and catch enough of them...