>Thankyou for the answer. Another sort of close question.
>     I do Eps. Those on our Southern shores
>include angulatum, humphreysi, tollini, and
>multistriatum. They are all
>distinguishable---but fairly close. The question
>is: Is there a common ancestor?

The answer is of course yes. The Epitoniidae
evolved from the Zygopleuridae. Most Jurassic
zygopleurids looke VERY much like primitive eps
(say Acirsa) but with ribbed protoconchs (very
similar to those of the most primitive eps, the
Nystiellinae... and that is no coincidence). Alex
Nützel in Germany would argue that Nystiellinae
should be raised to familial level due to the
protoconch and its similarity to the allied
family Janthinidae, but I see no god reason to do
so. Anyway, it would probably be impossible to
draw a definite line between Zygopleuridae and
Epitoniidae.

Of the species you mention, Art, if they are a
clade (closely-related) then they will share a
common ancestor. It is also quite possible that
one or more of these mentioned spp are ancestral
to one or more of the others. Ancestors don't die
off just because they have successfully
reproduced!

>  Have shorelines chaged too much to find one?
>Not just Eps. Is there a "Mother-of-all"
>Pectens? Is there any family to which one can
>say: "Meet your progenitor!"

Scallops are derived almost certainly from the Permian Aviculopectinidae.
--
Andrew Grebneff
Dunedin, New Zealand
64 (3) 473-8863
<[log in to unmask]>
Fossil preparator
Seashell, Macintosh & VW/Toyota van nut
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Q: Because it reverses the logical flow of conversation.
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