Boy that really does put the answers to the questions, thank you for your time with this Dr. Campbell. It would then figure
that the Smithsonian Institute would have the largest database and collection of the before mentioned fossils. One other
question then if you don't mind, Being that the "pleurotomaria" are a rather fragile group are many fossil specimens found
that are somewhat complete? Are these fossils  found mainly in shale?
Any appropriate websites to future my new investigation on this subject.... Thank you again for the detailed reply to my
earlier questions.....
Mark & Peta Bethke
Hollywood FL.
----- Original Message -----
From: David Campbell <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, May 19, 2000 11:54 AM
Subject: Re: pleurotomaria=perotrochus,,,why?


| > I've been sorting through my pleurotomaria collection and have been stumped by why they decided
| > to break the family name up
| > into at least three categories, pleurotomaria, perotrochus and entemnotrochus.... is there an
| > easy explanation as to why this
| > was instituted and how these families are different. I know there 's  probably a lengthy
| > explanation so if it's easier to
| > guide me towards a book that would be helpful that to would be most appreciated..........
|
| The Family Pleurotomariidae includes a wide variety of fossil forms, including true Pleurotomaria.
| The Treatise on Invertebrate Paleontology, volume I (that is a capital letter i and not Roman
| numeral one) Mollusca 1 has a detailed survey of the genera, although the Paleozoic genera have been
| extensively reclassified since then.  The modern forms seem to represent distinct lineages from the
| late Mesozoic and so are recognized as multiple genera.  Entemnotrochus has a very long slit and an
| open umbilicus, and is typically proportionally tall and straight-sided.  Perotrochus and
| Mikadotrochus have short slits and closed (Perotrochus) or very narrow (Mikadotrochus) umbilicus,
| with Perotrochus typically low and rounded and Mikadotrochus intermediate in height and form.
| Height of the slit on the whorl is also important.  There is some variation, though-in the Eocene of
| North Carolina we have a low, rounded Entemnotrochus which I will hopefully name soon.  Dr.
| Harasewych, at the Smithsonian, was working on a new genus for some of the modern forms but I do not
| think it is published yet.
|
| Dr. David Campbell
| UNC-CH Geological Sciences
| Chapel Hill NC
| [log in to unmask]
|