Nomenclatural question

["A.P. Hazen" <a.hazen@philosophy.unimelb.edu.au>]

(We had a discussion of the "Eu-" prefix a little while back.  At the 
other end of taxon-nomenclature...)
A number  of taxa with names like Blankomorpha and Blankiformes have 
been defined in recent years to cover extinct critters which, before 
the cladistic revolution, would  have been called ancestral Blanks, 
but which have had the bad luck not to leave living descendents and 
so are "outside the crown group Blank."  My sense  is that when  both 
suffixes have been used, Blankomorpha is the more inclusive.  Is 
there actually an established convention governing this?
--
Allen Hazen
Philosophy Department
University of Melbourne