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Re: cause of Gigantism in sauropods



2011/2/7 Habib, Michael <MHabib@chatham.edu>:
> I find it interesting that to some extent, if we considered felid 
> predator:prey ratios to be an acceptable proxy for theropods (which I doubt, 
> actually, more on that some other time), then the carnivora discussion speaks 
> to some extent in favor of both models: many felids are capable of taking 
> down prey a few times their mass, but very few do so regularly.  Bobcats 
> apparently have more skill in this than other cats, or else they encounter 
> wounded/injured animals more frequently.  I also note, again, that the 
> inverse size effect seems to hold (though it's going out on a limb a bit): 
> smaller felids, like bobcats, entertain greater maximum prey:predator size 
> ratios than larger solitary cats.
>
>
Contrarily, at least for carnivorous mammals, it seems that larger
carnivores are the ones that generally hunt relatively larger prey,
according to Carbone et al. (2007). It looks likely to me in cats, for
lynxes commonly survive on rabbit, which is smaller than the lynx,
while lion most commonly prey upon gnu, which is larger than the
lioness and easily killed by one lioness. Tigers also most commonly
prey on deer near their size range. Also, as far as I can tell, cats
the size of the domestic one generally hunt pigeon-sized prey, and not
much larger. As the size range, and probably physiology of carnivorous
mammals is not necessarily the same as for non-avian theropods, we
can't be sure what way dinosaur proportional prey size scaled. I am
not aware of similar scaling studies in carnivorous birds and crocs,
which would be better to infer the dinosaurian condition than mammals.

Reference:
Carbone C, Teacher A, Rowcliffe JM, 2007 The Costs of Carnivory. PLoS
Biol 5(2): e22. doi:10.1371/journal.pbio.0050022