>David,
>  Quite a few Pliocene taxa have traversed into the Recent epoch.  Just
>because one taxon is in the Pliocene and a "related" one is in the Recent
>does not in and of itself make it a new species as opposed to one with
>that traverses several epochs.  It would be interesting to see by what
>criteria the two are felt to be different and then for researchers in the
>Pectinidae to see if they agree that these differences are sufficent to
>separate the two out as different taxa as opposed to considering them one
>and the same.
 
True, although the extinction rate for lower and mid-Pliocene species in
the eastern U.S. is exceptionally high.  In this particular case, those
researchers I know of who have looked at it agree that there are enough
differences (rib number, size, inflation) to warrant separation.  These do
not include the individual to whom you alluded, although with his
exceptionally low standard for recognizing new species, he would doubtless
agree that the two are distinct.
 
 
David Campbell
 
"Old Seashells"
 
Department of Geological Sciences
CB 3315 Mitchell Hall
University of North Carolina at Chapel Hill
Chapel Hill NC 27599-3315
USA
 
919-962-0685
FAX 919-966-4519
 
"He had discovered an unknown bivalve, forming a new genus"-E. A. Poe, The
Gold Bug