>   Here in Cincinnati, all our Brachiopods and Trilobites, Horn Corals, etc. are fossils. They range about 400 million years. Ordivician. The only sub-fossils we have serve on city council and the various judicial benches.<

Along with some of your Ordovician bivalves, those fossils are generally preserving the original calcite mineral layers.  You may also have some fossil to subfossil land and freshwater shells nearby, along with mammoth bones and other traces of the ice ages, when the politicians were younger.

>   But, seriously, is the term "sub-fossil" really relevant? Don't we have enough trouble with sub-species, form of, cf., "interesting variety", etc.?
>   When does a shell jump from just plain dead to sub-fossilization? Is there a percentage of replacement that must be met? It's all very confusing. I think I'll collect match-book covers.

There's no absolute cutoff between dead and subfossil.  Still smelly is probably not a subfossil.  Subfossil is more or less equivalent to long dead but not yet fossil.  It tends to imply that the material is not very good for telling about modern faunas.  Thus, a pile of unionid shells on the bank just left by a muskrat and still having periostracum and maybe some meat would not be subfossils, but a pile of unionid shells buried in the river bank, with all the periostracum gone, would probably qualify as subfossil.

    Dr. David Campbell
    Old Seashells
    University of Alabama
    Biodiversity & Systematics
    Dept. Biological Sciences
    Box 870345
    Tuscaloosa, AL  35487-0345 USA
    [log in to unmask]

That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at Droitgate Spa