Pleuroceras

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Pleuroceras
Pleuroceras sp.

Pleuroceras sp.

Temporal occurrence
Upper Pliensbachium
Locations
Systematics
Cephalopods (cephalopoda)
Ammonites (ammonoidea)
Ammonitida
Eoderoceratoidea
Amaltheidae
Pleuroceras
Scientific name
Pleuroceras
Hyatt , 1868

Pleuroceras is a genus of moderately evolutionary ammonites (not to be confused with the genus of the same name from the order Diaporthales of the hose fungi ). She's index fossil in Upper Pliensbachian ( Domerium ) in the after spinatum Pleuroceras named spinatum zone .

Initial description and naming

The genus Pleuroceras was first described by Alpheus Hyatt in 1868. Its name is a word created from the two Greek words πλευρά pleurá (rib, flank) and κέρας kéras (horn), thus translating as "rib horn". The name refers to the striking ribbing of the ammonite.

characterization

With N = 0.42 to 0.46, Pleuroceras is a moderately evolved (wide-navel) genus of ammonites. The winding cross-section of the phragmocone is elliptical to rectangular with rounded ventro-lateral corners. A clear, rope-shaped keel runs in the middle of the vent - a synapomorphism of the Amaltheidae. This is accompanied by grooves (sulci), which can be shallow, sometimes deeper. Often, however, sulci are also completely missing and the keel is then only surrounded by a flat ventral plane. In the course of ontogenesis , the keel loses its constrictions in some taxa and then appears smooth. The ornamentation on the flanks of the phragmocone consists of very strong, straight radial ribs, hence the name of the genus. Tubercles can develop on them at the ventro-lateral margin. The ribs are sometimes slightly raised at the edge of the umbilical.

Systematics

Pleuroceras hawskerense from Switzerland

The genus Pleuroceras belongs to the family of Amaltheidae Hyatt , 1867 within the superfamily of Eoderoceratoidea Spath, 1929 , which had displaced the Psiloceratoidea since the beginning of the Pliensbachian .

The following taxa are known of the genus Pleuroceras :

A synonym of Pleuroceras is Paltopleuroceras Buckman, 1898 .

Amaltheus and Amauroceras act as sister taxa .

phylogenesis

Phylogenetic development of the genus Pleuroceras

It is generally assumed that the genus Pleuroceras emerged from the sister genus Amaltheus . Christian Meister (1988) sees the phylogenetic development starting from Amaltheus margaritatus via Pleuroceras transiens to Pleuroceras solare .

Ammonite zone

Pleuroceras salebrosum

The genus Pleuroceras is a key fossil and defines the fifth and last ammonite zone of the Pliensbachian, the Spinatum zone . The Spinatum Zone follows the Margaritatus Zone and is in turn overlaid by the Tenuicostatum Zone of the Lower Toarcian .

The spinatum zone is in turn divided into two sub-zones (from the hanging wall to the horizontal ):

  • Hawskerense subzone after Pleuroceras hawskerense
  • Apyrenum subzone according to Pleuroceras apyrenum

Way of life

Pleuroceras solare from Franconian Switzerland

The individuals of the genus Pleuroceras were probably very fast swimming marine carnivores , which far away from the coast populated the shallow, but also the deeper calcareous subtidal , and followed drifting plankton . They were also on the shelf area further out and also above the shelf ramp.

Occurrence

Occurrences of the genus Pleuroceras in Germany are Reichenbach an der Fils in Baden-Württemberg , Altdorf near Nuremberg , Kalchreuth and Wassertrüdingen in Middle Franconia , Buttenheim and Eggolsheim near Forchheim (Unterstürmig) in Upper Franconia and Sulzkirchen near Berching in the Upper Palatinate (all Bavaria ), Cremlingen in Lower Saxony and Velpe in North Rhine-Westphalia . In Austria the genus appears in the Lias of the Lienz Dolomites . In Hungary the Bakony Forest is to be mentioned.

Pyritized Pleuroceras spinatum from the Gard department in France

The sites in France include Champfromier in the Ain department , the Causses near Millau in the Aveyron department , Lixhausen in the Bas-Rhin department , Lanuéjols in the Gard department , the Lac de Charmes in the Haute-Marne department , Charmoille in the Haute-Saône department and Jard- sur-Mer and Péault in the Vendée department .

In Italy , echinoderm limes and marls should be mentioned near Varese . The discovery area of Pleuroceras in Serbia is near Pirot in the Stara Planina . In Spain , the Barahona formation near Almonacid de la Cuba ( Central Iberian chain south of Saragossa ) also leads the genus Pleuroceras .

Outside Europe, the genus Pleuroceras appears in North Africa in the Bayada Formation of the Traras in northwest Algeria , but also in North America , on the Halfway River in British Columbia , in the Kingak Formation in the northern Yukon (both Canada ) and in Alaska ( United States ).

literature

  • William Joscelyn Arkell et al .: Mesozoic Ammonoidea. Treatise on Invertebrate Paleontology. Geological Society of America and University of Kansas Press, 1957.
  • Andrew H. Caruthers et al: Pliensbachian-Toarcian (Early Jurassic) Ammonoids from the Luning Embayment, West-Central Nevada, USA In: Bulletins of American Paleontology . Number 393, 2018, p. 1-84 . [1]
  • Raymond Cecil Moore : Treatise on Invertesbrate Paleontology . Part L. Mollusca 4. Ammonoidea. Geological Society of America, 1957, pp. 248 .
  • Kevin N. Page: The Lower Jurassic of Europe: its subdivision and correlation . In: Geological Survey of Denmark and Greenland Bulletin . tape 1 , 2003, p. 23-59 .
  • Rudolf Schlegelmilch : The ammonites of the southern German Lias: an identification book for fossil collectors and geologists. - 2nd edition Gustav Fischer Verlag, Stuttgart, Jena, New York 1992, p. 241 .

Individual evidence

  1. ↑ JJ Sepkoski: A compendium of fossil marine animal genera . In: Bulletins of American Paleontology . tape 363 , 2002, p. 1-560 .
  2. ↑ Christian masters: ontogeny et évolution of Amaltheidae (Ammonoidea) . In: Eclogae géol. helv. 81 No. 3, 1988, p. 763-841 .
  3. ^ J. Blau and C. Meister: Liassic (Pliensbachian) ammonites from the Lienz Dolomites (Eastern Tyrol, Austria) . In: Yearbook of the Federal Geological Institute . tape 134 , 1991, pp. 171-204 .
  4. ↑ M. Meyer, M., C. Meister and R. Wernli: Stratigraphie du Lias de Champfromier (Ain) . In: Géologie de la France . No 1. BRGM & SGF, 2000, p. 53 .
  5. ^ Christian Meister: Les ammonites du Domérien des Causses (France) . In: Cahiers de Paléontologie . Center National de la Recherche Scientifique, 1989, p. 60 .
  6. ^ J. Bardin, I. Rouget and F. Cecca: Late Pliensbachian (Early Jurassic) ammonites from Lac de Charmes (Haute-Marne, France): Systematic, biostratigraphy and palaeobiogeography . In: Geodiversitas . tape 35 (2) . Muséum National d'Histoire Naturelle, Paris 2013, p. 328 .
  7. ↑ AM Bourdenet: Les Pleuroceras du Domérien supérieur de Charmoille (Haute-Saône) . In: Annales Scientifiques de l'Université de Besançon - 3e série, Géologie . fasc. 18. Université de Besançon, 1964.
  8. ↑ J. Jankicevic, D. Rabrenovic and V. Radulovic: Stratigrafske i paleontoloshke karakteristike Lijasa u Zabrdju (Stara Planina) [Stratigraphic and palaeontological characteristics of the Liassic of Zabrze (Stara Planina)] . In: Geoloski Anali Balkanskoga Poluostrva . tape 47 , 1983, p. 161-182 .
  9. ↑ MJ Comas-Rengifo et al .: El Jurasico Inferior en la seccion de Almonacid de la Cuba (sector central de la Cordillera Iberica, Zaragoza, Espana) . In: Cuadernos de Geologia Iberica . tape 25 , 1999, pp. 27-57 .
  10. ↑ S. Elmi, A. Marok, A. Sebane and Y. Alméras: Importance of the Mellala section (fanfare Mountains, northwestern Algeria) for the correlation of the Pliensbachian-Toarcian boundary . In: Volumina Jurassica . tape 7 , 2009, p. 37-45 .
  11. ↑ TP Poulton: Hettangian through Aalenian (Jurassic) guide fossils and biostratigraphy, Northern Yukon and adjacent Northwest Territories . In: Geological Survey of Canada Bulletin . tape 410 , 1991, pp. 1-95 .