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Re: cause of Gigantism in sauropods



2011/2/10 Raptorial Talon <raptorialtalon@gmail.com>:
> Titanosaur nests have what, 200 eggs a clutch in some cases?

I think less than 30, according to the chapter by Horner and Padian in
"The Dinosauria Second Edition"

> Given that sauropods also took at least several years to reach truly
> large sizes, there would also have been moderate-sized individuals of
> different generations available at all times of the year, and there's
> no biomechanical evidence to suggest that these columnar, graviportal
> juveniles were faster than the large theropods in their environment.
> They would thus have made easier targets, and attrition rates would
> have been high, although hypothetically mitigated somewhat by any herd
> behavior.
>
> Also, IIRC, stegosaurs were the next-most common herbivores in many
> Late Jurassic environments, at the very least, and the young of these
> - while more prickly - would have been little faster. Adults of the
> larger iguanodontians probably weren't all that much faster than large
> theropods, either (no direct analysis of this that I'm aware of, other
> than tyrannosaur vs hadrosaur which favors the former for top speed),
> so while I wouldn't expect sprints after dryosaurs to be very common,
> the occasional snagging of a camptosaur at a watering hole seems very
> plausible.

Even the youngsters of faster dinosaurs may not be faster than a
heavy, not very cursorial predator (partially because smaller stride
lenght and partially because of the amount of cartilage in their long
bones?). Bears can outrun juvenile deer, but not adults.