Oxynoticeras

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Oxynoticeras
Oxynoticeras oxynotum

Oxynoticeras oxynotum

Temporal occurrence
Sinemurium
189.6 to 164.7 million years
Locations
Systematics
Cephalopods (cephalopoda)
Ammonites (ammonoidea)
Ammonitida
Psiloceratoidea
Oxynoticeratidae
Oxynoticeras
Scientific name
Oxynoticeras
Hyatt , 1875

Oxynoticeras is a genus of involute, smooth-shelled ammonites with a distinct keel. It occurswidelyas a key fossil in the upper Sinemurian ( Lotharingian ).

Initial description and designation

Alpheus Hyatt first scientifically described the genus Oxynoticeras in 1875. Its name is a word created from the three Greek words ὀξύς oxys (sharp), νότος  nótos (back) and κέρας kéras (horn), ie pointed horn.

characterization

The genus Oxynoticeras is characterized by a fairly smooth shell, which is covered by only very flat and relatively indistinct ribs. It also stands out due to its very distinctive and sharp-edged keel, hence its name. Their average size is less than 10 centimeters, but rare finds of up to 40 centimeters are known. The phragmocone is strongly involute, recognizable by a very low parameter N of 0.14 (where N = U / D or umbilical diameter U / total diameter D). For comparison, very evolutionary taxa such as Dactylioceras have a much higher N of 0.54 to 0.62.

Way of life

The individuals of the genus Oxynoticeras were fast- swimming carnivores of calcareous sea areas that populated the subtidal up to the shelf slope off the coast .

Systematics

The genus Oxynoticeras belongs to the family of Oxynoticeratidae (subfamily Oxynoticeratinae ) within the superfamily of Psiloceratoidea . The following taxa are known from her:

As be sister act Cheltonia , Gleviceras , Hypoxynoticeras , Oxynoticeroides , Paracymbites , Paroxynoticeras , Radstockiceras and Slatterites .

A synonymous name of the genus Oxynoticeras is Oxynotoceras Buckman, 1894 .

Ammonite zone

The genus Oxynoticeras is a key fossil in the Oxynotum zone (ammonite zone named after Oxynoticeras oxynotum ) and in the Raricostatum zone (named after Echioceras raricostatum ) which ends the Sinemurium.

The oxynotum zone overlying the obtusum zone is divided into two subzones, the Simpsoni subzone in the lying wall and the oxynotum subzone in the hanging wall . The basal Simpsoni subzone forms the Gagateum biozone, which is made up of three horizons (horizons XVII to XIX of the Lotharingium): the horizon of Gagaticeras exortum lying down, above the horizon of Gagaticeras gagateum and the horizon of Paroxynoticeras driani in the hanging wall . The Oxynotum subzone forms the Oxynotum biozone, which is also divided into three horizons (horizons XX to XXII of the Lotharingium): the horizon of Oxynoticeras oxynotum at the base, followed by Bifericeras bifer and Gleviceras doris in the top. The genus Oxynoticeras appears only in the fourth horizon of the Oxynotum zone.

In the Raricostatum zone, the genus Oxynoticeras occurs exclusively in the basal densinodulum subzone. This is divided into a Delicatum biozone in the lying position, an Edmundi biozone and a Radiatum biozone in the hanging wall. The Delicatum biozone consists of the only horizon of Plesechioceras delicatum (horizon XXIII of the Lotharingium). The Edmundi biozone has four horizons (horizons XXIV to XXVII of the Lotharingium), in the lying position the horizon of Crucilobiceras subplanicosta , above the horizon of Oxynoticeras lymense , the horizon of Eoderoceras bispinigerum and finally the horizon of Eoderoceras armatum in the hanging wall . The Radiatum Biozone is composed of two horizons (horizons XXVIII to XXIX of the Lotharingium), the horizon of Echioceras radiatum at the base and the horizon of Echioceras sp. 3 in the top.

In the Tethys area, the horizon of Oxynoticeras oxynotum, in contrast to the Northwest European Shelf Sea, extends over almost the entire Oxynotum biozone; Paroxynoticeras salisburgense only appears in the hanging wall . Above it then follows the horizon of Gleviceras rigidum , which extends down to horizon XXV. The horizon of Oxynoticeras lymense is not developed, as are the following horizons XXVI to XXIX of the densinodolum zone.

Occurrence

Well-known sites of the genus Oxynoticeras in Germany are Blumberg , Balingen and Holzmaden in Baden-Württemberg and Rottorf am Klei in Lower Saxony . In the Chiemgau Alps it appears at Staudach-Egerndach . For Austria , the red limestone from Adnet in the state of Salzburg and the location Lorüns in Vorarlberg are to be mentioned . The deposits in Hungary are in the Jura of the Bakony Mountains .

In France , the genus Oxynoticeras appears in the middle Lotharingium of the Saône-et-Loire department , in Pougues-les-Eaux and Saint-Benin-d'Azy in the Nièvre department and in Jard-sur-Mer in the Vendée department . In England it can be found in the Lias of Castle Cary and Radstock in Somerset as well as on the coast at Charmouth in Dorset and at Robin Hood's Bay in Yorkshire . Deposits in Northern Ireland are at Collin Glen and Portrush . The Lusitanian Basin of Portugal is also home to the genus Oxynoticeras (in the Água de Madeiros formation near São Pedro de Moel ).

Locations outside of Europe are the Moghara Formation east of the Gulf of Suez in Egypt , Graham Island off British Columbia and the Richardson Mountains of the Northwest Territories in Canada .

literature

  • WJ Arkell et al .: Mesozoic Ammonoidea. Treatise on Invertebrate Paleontology. Geological Society of America and University of Kansas Press, 1957.
  • 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. ↑ Jean-Luc Dommergues, Kevin N. Page and C. Meister: A detailed correlation of Upper Sinemurian (Lower Jurassic) ammonite BioHorizons between Burgundy (France) and Britain . In: Newsletters on Stratigraphy . tape 30 , 1994, pp. 61-73 .
  3. ↑ M. Corna et al .: Sinémurian . In: E. Cariou and P. Hantzpergue, Biostratigraphie du Jurassique ouest-européen et méditerranéen: zonations parallèles et distribution des invertébrés et microfossiles (eds.): Bulletin du Center Recherches Elf Exploration Production Mémoire . tape 17 , 1997, pp. 9-14 .
  4. ↑ Kevin N. Page: The sequence of ammonite correlated horizons in the British Sinemurian (Lower Jurassic) . In: Newsletters on Stratigraphy . tape 27 , 1992, pp. 129-156 .
  5. ↑ Joachim Blau and Christian Meister: Upper Sinemurian ammonite successions based on 41 faunal horizons: an attempt at worldwide correlation . In: RL Hall and PL Smith, Advances in Jurassic research 2000 (Eds.): Proceedings of the 5th International Symposium on the Jurassic System. GeoResearch Forum . tape 6 , 1999, p. 63-12 .
  6. ↑ B. and C. Geczy Master: Les ammonites you Sinémurien du et Pliensbachien inférieur de la montagne du Bakony (Hongrie) . In: Revue de Paléobiologie . tape 26 (1) , 2007, pp. 137-305 .
  7. ↑ NTJ Hollingworth, DJ Ward, MJ Simms and P. Clothier: A temporary exposure of Lower Lias (Late Sinemurian) at Dimmer Camp, Castle Cary, Somerset, south-west England . In: Mesozoic Research . tape 21 , 1990, pp. 63-180 .
  8. ↑ M. Edmunds, M. Varah and A. Bentley: The ammonite biostratigraphy of the Lower Lias "Armatum Bed" (Upper Sinemurian-Lower Pliensbachian) at St Peter's Field, Radstock, Somerset . In: Proceedings of the Geologists' Association . tape 114 (1) , 2003, pp. 65-96 .
  9. ↑ MJ Comas-Rengifo et al .: El Sinemuriense Superior (cronozonas Oxynotum y Raricostatum) en la región de S. Pedro de Moel (Cuenca Lusitánica, Portugal) . In: Comunicações Geológicas . 100, Especial I, 2013, p. 15-1 .
  10. ↑ Unidade de Geologia, Hidrogeologia e Geologia Costeira , at www.lneg.pt, accessed on October 13, 2018
  11. ^ H. Douvillé: Les terrains secondaires dans le massif du Moghara à l'Est de l'isthme de Suez . In: Mémoire de l'Académie des Sciences, Paris . tape 54 (2) , 1916, pp. 1-184 .
  12. ↑ M. Aberhan: Early Jurassic Bivalvia of western Canada. Part I. Subclasses Palaeotaxodonta, Pteriomorpha, and Isofilibranchia . In: Beringeria . tape 21 , 1998, pp. 57-150 .
  13. ^ DV Ager and GEG Westermann: New Mesozoic Brachiopods From Canada . In: Journal of Paleontology . tape 37 (3)) , 1963, pp. 595-610 .