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Re: cause of Gigantism in sauropods



> If indeed.

In the back of my mind I was considering the resistance of muscle and
connective tissue, too, and the post pointing out the depth of the
neck probably protecting the arteries sort of confirms some of my
suspicions regarding total resistance here.

> Please note that any force transmitted by the sauropod to the theropod
> through the teeth effectively increases the bite force.

Unless the force is being transmitted perpendicular(ish) to the
craniocaudal dimension of a flattened tooth. Pressing my hand against
the flat side of a knife does more to push the knife along with my
hand than it does to add to the knife cutting through that hand. Given
the kind of rotational forces and general shifting about of a
fight-or-flight animal, not all vectors are going to be advantageous
for the theropod.

> If certain sauropods developed specific defenses against biting on the base
> of the neck, that alone is evidence that they were being bitten.

So if derived titanosaurs had armor on their backs, even though they
were among the smallest, ergo smallest-necked, and lowest-necked
sauropods, what would that tell us?

> And it seems to me that slicing is just what is needed.

To do what exactly? Clamp off the blood vessels? I think we're talking
past each other here.

> That said -- once again, a post on the topic of whether giant theropods
> _could_ kill giant sauropods, and relatively easily at that, has morphed
> into a "debate" about whether theropods _did_ kill giant sauropods, or were
> "likely" to have killed them regularly, or whatever.

You can't entirely dismiss the value of using modern analogues as
general parameters for past processes (putting "likely" in quotes
there). We can say with a meaningful degree of confidence that attacks
by large theropods on large sauropods were not the norm, based on
consistent observations across many modern taxa. That may not be
saying much overall, but it's a constraint that at least allows us to
exclude a range of other alternatives.

Also, Godzilla doesn't just go down to Cthulhu. True fact.

> As that is an entirely different subject, and one I do not see as a topic I
> can make a useful contribution to, I will let you have the last word.

Thank you.

As far as I can tell, gigantism in sauropods is not adequately
explained by predator-deterrence either alone or primarily, although
as a secondary benefit of digestive efficiency and other corollary
factors, it may have contributed to some degree.

I do note that giant theropods tend to come from the same ecosystems
as giant sauropods; rarely is this not the case. If being big allows a
theropod to kill a sauropod more easily, we would expect to see giant
theropods cropping up alongside smaller sauropods before seeing giant
sauropods alongside giant theropods, with the biomechanical limits on
a giant biped ultimately limiting the predator even once outstripped
by the prey. (AFAIK, the size ratio between the two remains somewhat
constant as both progress from the Early to Late Jurassic - but
probably not too well constrained there).The association certainly
implies some relevance as a food source, although theropod size could
have been driven by the increasing relative size of older juveniles
rather than adults, and in any case correlation doesn't prove
causation and total prey biomass or other factors could be more
relevant.