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Re: Dwarfism in Dinos
I recently sent Dinogeorge a long and rather rambling account of why I
think Cope's Rule is not supported by evolutionary theory, and why it
is possible that dwarfism is a major component of evolution, and
indistinguishable from speciation. I do not have the time to go into
it further, and I'd rather not forward the letter to the group,
although he is welcome to. A brief summary goes like this:
1) Many of the factors which contribute to dwarfism are the same
factors which we believe are involved in speciation.
2) It is probable that, for various reasons which cladistic analysis
is intended to overcome, that the descendants of dwarves are not
always recognized as being related to the original, larger species.
3) It is possible that paedomorphosis (which I assume is often
involved in dwarfism), may "turn back the clock" on derived
characteristics, disguising the close relationship of a dwarf and it's
4) Any species which, at some stage in it's life, is a certain mass,
may evolve into a a new species of that mass, even if that mass is
considerably less than the mass of the parent species.
The argument goes on, but that's the upshot. Note that I have not
gone into the evolutionary pressures for dwarfism, I believe they
ought to be clear (niche partitioning was just mentioned, for
Jonathan. R. Wagner
P.S. Is it possible that, in common parlance, these "dwarf" species,
such as the mammoths, might be better termed "midgets (a midget being
a stunted, but proportional human, as opposed to a disproportionate
dwarf), while the dinosaurs mentioned, which have probably gone on in
evolution beyond being a miniature of another species, should be
considered proper "dwarves" of a larger phenotype?