(c) Rachaimer Dactylioceras sp.
Unteres Toarcium
Dotternhausen 1975
Sammlung georolf
(c) Rachaimer Dactylioceras sp.
Unteres Toarcium
Schlaifhausen (Franken)
Sammlung georolf
(c) Rachaimer Dactylioceras sp.
Unteres Toarcium
Dotternhausen
Schrägeinbettung
Sammlung georolf
(c) Rachaimer
Dactylioceras sp
Lower Toarcian
Dotternhausen
food residue collection
Dactylioceras sp
Lower Toarcian
Dotternhausen
food residue collection
an important and key in the Lower Toarcian ammonites georolf genus is the genus Dactylioceras . It even speaks of Dactylioceratenschichten.
The top image shows such ammonites, as occurs normally in the feinlaminierten, bituminous Tonmergelfazies the Lower Toarcian. The ammonite is - has been embedded - lying flat on the sediment. When compaction and dewatering of the original clay slurry which took place in the course of diagenesis, the volume to about 5% of the original volume was compressed. The case is therefore completely flattened and dissolved away the calcareous shell. It is only a thin skin of Conchyolin and pyrite obtained.
In the second image of a physically intact Dactylioceras Franken is shown. It is in the rock around a Schaumkalk. The fossils are preserved as casts.
The condition is so heavily dependent on the nature of the sediment in which the fossil is embedded.
In the third image is the front for the "oil shale" of the Lower Toarcian typical condition. The embedding location is very unusual: The ammonite and declining to the sea bed diagonally in the sediment stuck and was so embedded. Due to the compaction of the case has been strongly sheared.
Im vierten Bild ist die Schale eines Dactylioceraten stückweise eingelagert. Es handelt sich um einen Fraßrest: Ein Fisch oder Saurier hat einen Dactylioceraten gefressen, indem er das Gehäuse zerknackte und die Weichteile verschlang. Die Scherben des Gehäuses wurden deshalb zerstreut.
Da es am Grund des "Ölschiefermeeres" kaum Bodenleben gab (Sauerstoffmangel), handelt es sich um Reste, die aus dem oxischen Bereich stammen. Hätte z.B. ein Krebs einen solchen Ammoniten gefressen, so wäre die Schale nicht zerknackt, sondern regelrecht aufgeschnitten. Solche Stücke sind bekannt.
Literatur:
G EYER , G WINNER :
Einführung in the geology of Baden-Württemberg
Hense, Stuttgart
first Ed in 1964
F LEISSNER , R ÖDIGER :
The eternal sea
Franckh'sche Verlagshandlung
Stuttgart 1984
R S UDOLF CHLEGELMILCH :
The Lias ammonites of southern
Gustav Fischer Verlag Stuttgart
1976
oral as well. Information from the Geol-pal. Taxidermist F RITZ L ÖRCHER
The top image shows such ammonites, as occurs normally in the feinlaminierten, bituminous Tonmergelfazies the Lower Toarcian. The ammonite is - has been embedded - lying flat on the sediment. When compaction and dewatering of the original clay slurry which took place in the course of diagenesis, the volume to about 5% of the original volume was compressed. The case is therefore completely flattened and dissolved away the calcareous shell. It is only a thin skin of Conchyolin and pyrite obtained.
In the second image of a physically intact Dactylioceras Franken is shown. It is in the rock around a Schaumkalk. The fossils are preserved as casts.
The condition is so heavily dependent on the nature of the sediment in which the fossil is embedded.
In the third image is the front for the "oil shale" of the Lower Toarcian typical condition. The embedding location is very unusual: The ammonite and declining to the sea bed diagonally in the sediment stuck and was so embedded. Due to the compaction of the case has been strongly sheared.
Im vierten Bild ist die Schale eines Dactylioceraten stückweise eingelagert. Es handelt sich um einen Fraßrest: Ein Fisch oder Saurier hat einen Dactylioceraten gefressen, indem er das Gehäuse zerknackte und die Weichteile verschlang. Die Scherben des Gehäuses wurden deshalb zerstreut.
Da es am Grund des "Ölschiefermeeres" kaum Bodenleben gab (Sauerstoffmangel), handelt es sich um Reste, die aus dem oxischen Bereich stammen. Hätte z.B. ein Krebs einen solchen Ammoniten gefressen, so wäre die Schale nicht zerknackt, sondern regelrecht aufgeschnitten. Solche Stücke sind bekannt.
Literatur:
G EYER , G WINNER :
Einführung in the geology of Baden-Württemberg
Hense, Stuttgart
first Ed in 1964
F LEISSNER , R ÖDIGER :
The eternal sea
Franckh'sche Verlagshandlung
Stuttgart 1984
R S UDOLF CHLEGELMILCH :
The Lias ammonites of southern
Gustav Fischer Verlag Stuttgart
1976
oral as well. Information from the Geol-pal. Taxidermist F RITZ L ÖRCHER
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