[Taxacom] Mollusca, major subdivisions (Lipocephala and Glossophora)

[John Grehan]

If Lankester made Lipocephala and Glossophora were made sister groups
then I would think that neither is primitive or derived. Each would have
its own set of apomorphies to support their respective monophyly? 

John Grehan

> -----Original Message-----
> From: taxacom-bounces at mailman.nhm.ku.edu [mailto:taxacom-
> bounces at mailman.nhm.ku.edu] On Behalf Of Kenneth Kinman
> Sent: Wednesday, March 11, 2009 10:52 PM
> To: taxacom at mailman.nhm.ku.edu
> Subject: [Taxacom] Mollusca, major subdivisions (Lipocephala and
> Glossophora)
> 
> Dear All,
>       I am not familiar with the work of Lankester, 1889, but he
> apparently divided the molluscs into Lipocephala (for bivalves) and
> Glossophora (for the other, radula-bearing, molluscs).  To me this
seems
> to be a very natural division of molluscs, into primitive forms
(lacking
> a head and a radula) and those taxa which possess these
synapomorphies.
>       Unfortunately, the vast majority of malacologists today seem to
> believe that bivalves secondarily lost their head and radula.   My
> question is this.  Did Lankester believe that the headless,
> radula-lacking, bivalves were primitive or derived?
>              ---------Ken Kinman
> 
> 
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