>  Where was the elevation in status written. It seems a lot of work is done
> and things changed without knowing where or who did the work. Were any other
> Crepidula involved? Most of the new books, papers etc reflect a change, but
> few recite citations.

Few of the species once placed in Crepidula now remain there. The
shell form is produced by convergence, and there are major differences
if you look really closely... for instance, some have two shell
muscles (scars visible under edge of columellar plate) and some have
only one. Protoconch is important too.

The only paper I am familiar with that deals with genus-level changes
is Bruce Marshall's recent work on NZ species. For those who might
have NZ shells in their collections, Crepidula doesn't occur in NZ...
for the Recent species Maoricrypta is correct. And for those with the
species once known as C. monoxyla (Lesson 1830), you are more likely
to have M. sodalis Marshall 2003, due to the discovery that there are
2 species which look similar, but M. monoxyla lives only on the
OUTSIDE of gastropod shells (and so has a convex exterior) and what
lives inside dead shells with hermitcrabs is M. sodalis, which is flat
to concave.

From the fossil record in NZ it can be seen that outr "slippers"
evolved from the Calyptraealike Sigapatella (another convergence
there?) via the Paleocene S. lamellaria (Finlay & Marwick 1937).

An interesting lineage led to some large long narrow fossil species
which lived in stacks of up to 10 individuals, apparently lying on
sandy seafloors and must have filterfed. I don't know what genus these
Crepidulalike beasts belong to... may need a new one.

--
Regards
Andrew Grebneff
Dunedin, New Zealand
Fossil preparator
Mollusc, Toyota & VW van nut

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