Fossils of the Renggeri Marl
The Book Chapters
By Roland Himmler
Location Tarcenay road :
Border M/U Jurassic
In my opinion it is/was the ideal outcrop at the border of Middle / Upper Jurassic
Morphology / Sutur line
No contradiction to literature, in here just shown for better understanding
The logarithmical spiral
The impact of the logarithmical spiral on the shell is not discussed in literature
Diameter / Number of windings / Size
(See also snails of today)
Influence of the protoconch on the shell size is not discussed in literature
“Picked up” versus “in situ” (=digged)
Finding places: if layers are horizontal, there is no difference between “picked up” and “in situ”.
Pros and cons “in situ ” versus “picking-up”
Characteristics of a fana profile of a certain location stays quite stable after several visits when number of findings is above a certain amount (approx. 200)
Determining of names
(Subkommission fuer Jura-Stratigraphie and Prof.L.Hottinger – Uni Basel CH)
Giving names seem to be impossible but necessary.
Abnormal shells
Besides Hoelder, who in general restricts his comments on nomenclature, there seem to be no further hints in literature. Possibly because findings of these fossils are too scarce.
How does Cr. renggeri looks like ?
Possibly more species than only Cr. renggeri and piae do exist within Renggeri Marl.
“Close-up of sutur lines”
Top right: “HURT” (X) = sudden close-up -> normal
Bottom: Sudden close-up = micro-conch
The example top/right is possibly one out of hundred thousand.
Scaphidodites and dimorphismus
within Scaphidodites scaphitoides micro- and Macro-conch plus a new dimorph species (Scaphitodites gygii n.sp.) do exist
Comparison
recent sea snails versus Ammonite
As it looks like micro- and Macro-Conches seem to exist within recent sea snails as well.
Washed to a beach
Spirula spirula, crab and sea urgins
Surprisingly such fragile objects could be washed ashore without being damaged.
Sorted by “current” ??
Land snails of to-day can gather “without” (?) external influence. In this case they gather at the coolest point of their living area (breeze gives a bit cooling compared to the bottom)(no fact, too much interpretation).
Beach findings – usefull informations for fossils ?
Findings of to-day helping to explain fossil findings (hard ground necessary for corals to settle tec,).
“New findings”
At a first view, looking from the side they seem to be the same / very similar (though for sure they are different species, ….. though only ONE finding).
Pyritized findings as “dwarf” species
Top row: both Q. lamberti from Villers-s/s-MER (pyritized) and Herznach/CH (clay).
Below: C. cordatum (clay) nearly same size as lamberti at the top.
People in generall believe, pyritized ammonites are dwarf individuals
Other information:
How does calcite get into pyritised phragmocone
Unusual: Sutur line visible though inner part filling totally with calcit (UK_Charmouth07)
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