I guess reversed coiling is most likely (in marine gastropods) to
become fixed in a population in those forms which can still easily
"get it on". These taxa have internal fertilization and lay
eggcapsules, often with direct development; such individuals bearing
genes for reversal are much more likely then to meet others of their
ilk and reinforce the genepool.

I wonder then how a sinistral species of trochid might arise, that
is, Calliostoma (Sinutor) incerta of SE Australia?
--
Andrew Grebneff
Dunedin, New Zealand
64 (3) 473-8863
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Fossil preparator
Seashell, Macintosh & VW/Toyota van nut
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I want your sinistral gastropods!
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Q: Because it reverses the logical flow of conversation.
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