Joe here.  What an interesting observation re size of the Ordovician
gastropods. Made me look up some specimens. I have some lower paleozoic
specimens that are up to 1.5 inches...but as brachiopods increased in
numbers and dominance into the Silurian through to Permian...my gastropod
specimens shrink on average size...especially those in the Carboniferous
when there were some humongous brachiopods (up to 10 inches wide) around. On
the flip side: I also noticed that modern brachiopods (I'm working from
limited knowledge of these) tend to be on the small side (usually under an
inch?..at least the half dozen in my collection)...whereas today many
species of gastropods can be found in much larger sizes. Maybe only one of
these critters is dominant in a 'niche' at any given time.
P.S.  What's a Pringle? Are we Canadians being deprived of the cutting edge
og American food technology?
----- Original Message -----
From: "Art Weil" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Saturday, November 18, 2000 7:27 PM
Subject: Re: Hormotoma/ no modern descendents?


> Dear J & N;-
>     I'm sure everyone but me is right. It happens ---(rather frequently
lately).
> But in your comments on very ancient gastropods, I have made notice of
some
> features as we pack and move an entire museum collection. 1. I haven't
seen an
> ordivician gastropod over an inch in length. 2. I haven't seen these
ancient
> mollusks exhibiting either spines, or striations of any sort. 350 to 400
million
> years ago, they learned the art of coiling to save space. During that
period,
> the Mollusks appear to have lived darkly and quietly while Brachiopods
were
> strutting their variations on the stage of life.
>     The only other thing I have learned this week is that "Pringles"
aren't
> nearly as good as real, honest potato chips.
>         Art
>
> Joe and Nora wrote:
>
> > Hi Art,
> >
> > Some authours used to extend the Hormotoma superfamily
(pleurotomariacea)
> > into the the Devonian and Carboniferous (genera such as Rhineoderma,
Baylea,
> > etc.)...others saw no connection other than outward morphology. Raymond
> > Moore had this family extending to modern genera but later reduced it to
> > lower paleozoic... cutting the line to the upper paleozoic...others cut
the
> > line from upper paleozoic to the Mesozoic...gets complicated!!
> > Paleozoic gastropods are a very understudied group. They need attention.
A
> > good chunk of paleozoic paleontology is based on biostratigraphy and
> > gastropods have not been very useful in this respect. Much more useful
> > macrofossils for this purpose are rugose and tabulate corals and
> > brachiopods. I had the opportunity to work with a couple of 'doctor
> > emeritus' (old fossils themselves) and they never had any time or
> > inclination to look at gastropods....we spent our time thin sectioning
> > corals to determine rock ages, etc.   An aside to all this: most of the
> > preeminent paleozoic coral researchers(Sando, Pedder, Bamber,
> > Federosky,etc.) do not believe that modern corals (the scleractinians)
are
> > in anyway related to paleozoic corals. They see Mesozoic corals arising
from
> > some unknown group in the Triassic..but that is another story.
> > ----- Original Message -----
> > From: "Art Weil" <[log in to unmask]>
> > To: <[log in to unmask]>
> > Sent: Wednesday, November 15, 2000 8:41 PM
> > Subject: Re: Hormotoma/ no modern descendents?
> >
> > > Dear Joe;-
> > >     I understand the dieing out of Hormatoma----but did it do so
without
> > > branches, descendants, etc.? It appears nothing like  a "Slit-Shell",
but
> > very
> > > much like slim coiled families----Terebra, Epitoniidae, Miters, etc.
> > >         Art
> > >
> > > Joe and Nora wrote:
> > >
> > > > Hello Art,
> > > >
> > > > Joe here. I sifted through my collection and literature. All of our
> > > > 'Hormotoma' specimens are Ordovician or Silurian in age. This is
mostly
> > a
> > > > North American fossil (although also found 'rarely' in Europe). It
was
> > > > usually placed (despite its outward appearance) until the 1940's  in
the
> > > > superfamily Pleurotomariacea by some authors. Its kin, Mourlonia,
> > somewhat
> > > > resembles descendents through to the Pleurotmaria.
> > > > Subsequesnt authors do not place it in this superfamily but place it
in
> > > > agroup archaeogastropods with no further lineage. It is thought to
die
> > out
> > > > in the Silurian. It is thought by most to have no relationship with
the
> > > > modern pleurotomaria.
> > > > Most authors ( some exceptions) do not accept any known antecedents
of
> > the
> > > > modern Pleurotomaria until the Mesozoic age.
> > > > Your species 'gracilis' was first placed in the genus  Murchisonia
> > (Hall,
> > > > 1847) and subsequently changed by the author to Hormotoma sometime
in
> > the
> > > > 1850's (I 'think').
> > > >     Nora and I just obtained a scanner and it is surprising how well
it
> > > > scans small fossils. Sometime in the not too distant furue we'll
scan
> > some
> > > > paleozoic gastropods, mesozoic pleurotomaria, etc. and make them
> > accessible
> > > > to Conch-L subscribers to view.
> > > >
> > > > Original Message -----
> > > > From: "Art Weil" <[log in to unmask]>
> > > > To: <[log in to unmask]>
> > > > Sent: Tuesday, November 14, 2000 7:34 PM
> > > > Subject: Hormotoma
> > > >
> > > > > Dear (probably Old Seashells and Andy);-
> > > > >         What I have here is a Hormotoma gracilis (maybe
Homotoma?). It
> > > > > measures 13.48mm long and is about 400 million years old. Since a
> > > > > fleeting glance makes it look like an Epitonium (or Cerith or
other
> > > > > coiled critter) I wondered if there is some descendency from the
> > fossil
> > > > > that I have. Inquiring minds want to know.
> > > > >             Art