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Re: attack on dinosaur--horrific video



On Sun, Nov 25, 2007 at 11:45:36AM -0500, john bois scripsit:
> ----- Original Message ----- From: "David Marjanovic"
> <david.marjanovic@gmx.at>
>> ...reliance on nest defense does nowhere near guarantee extinction.
>
> Why has it not re-evolved in your view?  I mean, crocs are it, right?
> So, what is the probablity that nest defence strategy in terrestrial
> biomes has been eliminated by chance alone?  If it's a viable
> strategy, how come no one outside of crocs employs it?

But many birds *do* employ it; pretty much any raptorial bird or corvid.

There are eyewitness accounts of woodpeckers killing squirrels bent on
nest-raiding, come to that.

And what do you mean by "defence"?  Ground-nesting birds like
quail or grouse will decoy predators away.  This is plausibly active
defence.

I'd suggest that's it's most parsimonious to assume that, given that the
diversification race for terrestrial megafauna was won by viviparous
animals after the KT, the strategy hasn't re-arisen because the
oviparous megafauna haven't, and that the reasons for that aren't
required to consider predation whatsoever.

-- Graydon