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RE: Body Size Evolution in Mesozoic Birds



> Perhaps there could be another rule of decreasing
> size preceding  
> evolutionary novelty.

It's certainly so that being huge in comparison to
one's closest relatives does not exactly help. The
"being the right size" problem - the underlying
phenomenon behind Haldane's famous if apocryphal
"inordinate fondness for beetles" quote - is still
unresolved, though I suspect that a look at the
fractal dimension of (micro)habitat might be
insightful.

For the time being, all other things being equal a
smaller taxon can afford higher population sizes
and/or a more r-like strategy compared to a larger
taxon. Both would help an innovation maintain itself,
because it is not common that an evolutionary
innovation is 100% positive - in some way or another,
it usually disrupts an estabilshed equilibrium to some
degree.

Regards,

Eike


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