[Taxacom] How do fossil mollusc taxonomists manage?

[Dr. David Campbell]

How do fossil mollusc taxonomists manage?  By getting income from some 
other source.  

How do you identify fossil mollusks, or for that matter Recent ones 
that are often only known from shells?  Ideally, anatomical, molecular, 
and biogeographic data are integrated with the conchological data.  In 
cases of apparent conflict, look again at everything.  Did you amplify 
a pseudogene, or perhaps a male mitochondrial lineage in one taxon and 
a female lineage in the other?  Is convergence likely?  Is the 
traditional morphological classification based on a single 
symplesiomorphy, or is it better supported?   

For example, "Villosa" is a genus of freshwater mussel currently used 
for any lampsiline that is more or less ovate, does not have peculiar 
larval shape, does not have unusual elaboration of the gills for 
brooding, and generally has a mantle flap lure that's not like the one 
in Lampsilis.  Not surprisingly, it's highly polyphyletic in molecular 
analyses.  The groups supported by molecular analyses generally show 
common shell morphology when you go back and look at them.  But to 
identify a fossil mussel with Villosa or one of the other clades, I 
would first check what drainage region it was from, because freshwater 
mollusks are often very poor at interregion dispersal.  If the fossil 
is not from Atlantic or Arctic drainage of North America, it's almost 
certainly not even from the same tribe as Villosa.

-- 
Dr. David Campbell
425 Scientific Collections Building
Department of Biological Sciences
Biodiversity and Systematics
University of Alabama, Box 870345
Tuscaloosa AL 35487-0345  USA