[Taxacom] Evolution of molluscs and other invertebrates

Richard Petit r.e.petit at worldnet.att.net
Fri Jul 10 18:28:27 CDT 2009

Sorry, but I had a lapsus and forgot that many on this forum have no sense 
of humor.  If I had thought that the simple existence of a gastropod with a 
bivalved shell was important to the discussion, I would have stated why it 
was important.  It was a non-relevant fact that might have been unknown to 

My apologies to all.

dick p.

----- Original Message ----- 
From: "Dr. David Campbell" <amblema at bama.ua.edu>
To: "TAXACOM" <taxacom at mailman.nhm.ku.edu>
Sent: Friday, July 10, 2009 7:08 PM
Subject: Re: [Taxacom] Evolution of molluscs and other invertebrates

> Quoting Bob Mesibov <mesibov at southcom.com.au>:
>> Richard Petit wrote:
>> "Don't forget that Mollusca has bivalved gastropods."
>> Candidate  case for horizontal gene transfer of developmental genes?
> No.  The details of bivalved form are rather different.  In particular,
> the snails start out with a fairly normal single shell before starting
> to grow the second valve.  I think a recent paper actually looked at
> some key developmental genes and found the pattern to be different.
> Bivalved body plans turn up here and there in several taxa (various
> Crustacea, Brachiopoda, diatoms, etc.)
> There are also good transitional forms in the early Cambrian mollusks
> going from single shelled to bivalves.
> -- 
> Dr. David Campbell
> 425 Scientific Collections Building
> Department of Biological Sciences
> Biodiversity and Systematics
> University of Alabama, Box 870345
> Tuscaloosa AL 35487-0345  USA
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