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Showing results for tags 'wutachtal'.
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A complete specimen with the shell preserved on one side. The transition from phragmocone to body chamber can be seen on the mold on the reverse side where the shell no longer exists.
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Calcite mold of the phragmocone and part of the body chamber.
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- a180
- achdorf formation
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This is the index fossil of the murchisonae zone. This sample was disturbed either during burial or later tectonically at the point where the phragmocone meets the body chamber. The shell is completely preserved on one side showing clearly the typical ribbing. It is not quite complete, still missing about a half turn around the axes. Old German Chronostratigraphy: Dogger (Braunjura) beta Literature: Rieber,H. (1963): Ammoniten und Stratigraphie des Braunjura beta der Schwaebischen Alb, Palaeontographica Bd.122,Abt.A, Pp.1-89
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This species has long been a subject of contention as to its lineage, but Dietze (2014), following the chronospecies/genus concept, has managed to prove to the satisfaction of most that it belongs to the subfamily of the Leioceratinae. Rieber (1963) had placed it in the subfamily Staufeniinae and had named it Staufenia opalinoides, a name which most collectors and paleontologists adopted, since his work was the most comprehensive one on the ammonite fauna of the area for many years. This almost complete specimen has most of its shell intact. The band of variation of ribbing and other sculptural factors is relatively broad, but this here is a typical sample. Biostratigraphy: Murchisonae Zone, Sinon Bank 1, haugi Subzone Old German Chronostratigraphy: Dogger (Braunjura) beta Literature: Rieber,H. (1963): Ammoniten und Stratigraphie des Braunjura beta der Schwaebischen Alb, Palaeontographica Bd.122,Abt.A, Pp.1-89 Dietze et al (2014): Aalenian (Middle Jurassic) ammonites and stratigraphy of the Geisingen clay pit (SW Germany), Palaeodiversity 7: 61–127 Horn,E. (1909): Die Harpoceraten der Murchisonae-Schichten des Donau-Rhein-Zuges, Mitteilungen der Großh. Badischen Geologischen Landesanstalt, VI. Bd.1.Heft
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The samples of this species at this site are practically impossible to extract in one piece due to the large size and the discus-like shape of the fossil and also to the hardness and cleavage of the matrix. Therefore this one was extracted in several pieces which were then glued back together. All remaining cracks and crevices were then filled in with stonemeal. What we see here is just a complete phragmocone, which is apparent through the suture lines visible on the calcite mold seen in the second photo, where the shell broke off during extraction. The complete creature with body chamber probably had a diameter of ca. 40cm. This is the index fossil of this particular horizon. An Homaloteuthis sp. belemnite rostrum is attached at the mouth aperture. Biostratigraphy: Bradfordensis Zone, bradfordensis subzone, staufensis bank Old German Chronostratigraphy: Dogger (Braunjura) beta Literature: Rieber,H. (1963): Ammoniten und Stratigraphie des Braunjura beta der Schwaebischen Alb, Palaeontographica Bd.122,Abt.A, Pp.1-89
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- a805
- bradfordensis zone
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(and 5 more)
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To be seen on the matrix below the ammonite are 2 Myophorella formosa bivalves on the right and a Staufenia opalinoides ammonite. The shell on one side is completely preserved. The other side shows the calcite mold with sutures on the phragmocone. Only a small section of the body chamber on this specimen is preserved. If complete, it would probably have had a diameter of approximately 16cm. This is the index fossil of the subzone. Old German Chronostratigraphy: Dogger (Braunjura) beta Literature: Rieber,H. (1963): Ammoniten und Stratigraphie des Braunjura beta der Schwaebischen Alb, Palaeontographica Bd.122,Abt.A, Pp.1-89