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Re: cause of Gigantism in sauropods
I've heard that bobcats sometimes take down mule deer. A quick web search
turned up this:
From: Habib, Michael
Sent: Monday, February 07, 2011 1:11 PM
Subject: Re: cause of Gigantism in sauropods
On Feb 7, 2011, at 12:45 AM, <email@example.com> wrote:
So in the Morrison, the sauropod-theropod size gap seems smaller than the
elephant-lion one. I see little reason to believe that Saurophaganax or A.
maximus could not take down even Giraffatitan or Supersaurus.
Neat comparison with the body mass estimates (thanks for punching the
numbers!) but I'm not sure I quite agree with your conclusion. It seems
reasonable that something like Saurophaganax could take down something like
Giraffatitan under very rare, extreme circumstances, just as living
terrestrial macro-predators (or groups of them) very rarely kill much larger
animals than themselves. However, I see no reason to expect that such
events were common, or even occurred with a high enough frequency for us to
seriously consider them as major factors in our reconstructions of Mesozoic
ecology. Living terrestrial vertebrate predators rarely take prey even
three times their own mass, much less 6-8 times.
The elephant-lion size ratio probably does not represent the ratio at which
predation is regular or ecologically important; at best it is a ratio at
which a very rare predation event is still barely feasible - and that is for
a specific guild of predators and herbivorous mammals. The more important
size ratio is the maximum predator:prey mass ratio among *regular* predation
events. Phrased as a question: Of those large terrestrial animals that are
predated as adults with a high enough frequency for its impact on total
population mortality to be measurable, how large are their smallest
predators (or total mass of packs, if they are predated by groups)?
I don't know exactly what the answer to that question is, but qualitative
observation suggests that the size gap is pretty small. The vast majority
of predators, even large ones, mostly take prey smaller than themselves.
Even animals like water buffalo, which are a fraction of the size of
elephants, are large enough as adults to be predated upon rarely (albeit
more often than elephants).
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