Re: paleonet Tentaculitids

[meor hakif <hakif23@xxxxxxxxx>]

I agree,
The bulbous initial chamber is indicative of the
dacryoconarid tentaculitids. You should compare your
pictures with those in Boucek (1964), Tentaculites of
Bohemia, where there are some good thin section
plates.
I could also be of assistance, as i am working on
Devonian tentaculitids in Peninsular Malaysia

Meor Hakif Hassan,
Geology Department,
University of Malaya
50603 Kuala Lumpur

--- jmghist@netzero.com wrote:
> 
> Perhaps, I can add some information concerning the
> tentaculites.  Quite a few years ago, I worked on
> tentaculites from the Devonian in Ohio. (Master's
> thesis).  
> 
> First of all, the specimens in the thin-sections
> definitely look like tentaculites.  If they are,
> this would rstrict the the sediments to a
> Silurian-Devonian age.  The group appears to have
> become extinct at the Frasnian-Fammenian boundary,
> although I have heard reports that a very small
> number may have just made it through into the
> Fammenian.  They definitely did not last into the
> Carboniferous.  The specimens appear to be all
> fairly thin shelled with one or two showing an
> initial bulbous chamber (center of Tenta03-248). 
> This would suggest that they probably belong to one
> of the "planktonic" forms (my interpretation based
> on buoyancy studies of the shells) (e.g. Nowakia,
> Viratellina, Styliona).  The apparent lack of rings
> on many would narrow this down to one of the
> styliolinids.  I would need to reference some
> materials to be any more definite.  
> 
> As to your comment "they only been found within deep
> marine settings", tentaculites have been found at
> all depths.  In Ohio, large thick shelled forms
> (Tentaculites scalariformis) occur in relatively
> shallow-water limestones in some abundance.  These
> forms are as indicated above, thicker shelled and
> usually possess septa.  They also grow to fairly
> large size (30mm+).  The planktonic forms are
> usually much smaller (<10mm).
> 
> Any specific identification is difficult from
> thin-sections.  Macro views of specimens would allow
> more precise and definitive identification.  Do you
> have any such photos?
> 
> Most of the people I knew working on tentaculites in
> the 70's are probably not any more.  Although names
> that come to mind are Larssen (Sweden) (spelling?),
> Lardeux (France), Blind (Germany or Austria), and
> Hasjlasz (Poland) (again spelling?)
> 
> If you want, I can do some more checking around. 
> You can contact me either through paleonet or
> directly at jmghist@netzero.com.
> 
> John M. Ghist
> Bailey, Colorado
> USA
> 


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