Schlotheimia (ammonite genus)

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Schlotheimia
Schlotheimia depressa

Schlotheimia depressa

Temporal occurrence
Hettangium
200.3 to 199.6 million years
Locations
Systematics
Cephalopods (cephalopoda)
Ammonites (ammonoidea)
Ammonitida
Psiloceratoidea
Schlotheimiidae
Schlotheimia
Scientific name
Schlotheimia
Bayle , 1878

Schlotheimia is a genus of very evolutionary , ribbed ammonites from the Lower Jurassic . It acts as a key fossil in the upper Hettangian .

Initial description

The genus Schlotheimia was first scientifically described in 1878 by Claude-Émile Bayle . It was named in honor of Ernst Friedrich von Schlotheim . The latter had already named the taxon Schlotheimia angulata as Ammonites angulus or Ammonites angulatus ( type species ) in 1820 .

Way of life

The individuals of the genus Schlotheimia were fast swimming marine carnivores . They populated the marine , shallow subtidal , but were also found in siliciclastic basins in the open marine area and down to the shelf ramp in the deep subtidal.

Systematics

The genus Schlotheimia belongs to the family of Schlotheimiidae (subfamily Schlotheimiinae ) within the superfamily of Psiloceratoidea . It contains the following taxa:

Sister genera are Angulaticeras , Kammerkarites , Macrogrammites , Saxoceras and Waehneroceras .

Synonyms of the genus Schlotheimia are Aegoceras , Anguliferites Lange, 1951 , Saxoceras and Scamnoceras Lange, 1924 .

phylogenesis

According to Guex and colleagues, the genus Schlotheimia split off from the genus Kammerkarites together with the genera Franziceras and Saxoceras 200.5 million years ago . The genus Kammerkarites had developed from the genus Psiloceras , which had survived the mass extinction at the Triassic-Jura border around 201.3 million years ago. From the genus Schlotheimia the genera evolved around 200 million years Angulaticeras and Ectocentrites .

From the Schlotheimiidae , the Discamphiceratinae , the Arietitidae and the Lytocerataceae all later ammonites of the Jurassic and the Cretaceous (Neoammonites) should emerge.

Guide fossil and zoning

The taxon Schlotheimia angulata is the key fossil for the upper hettangium (Lias α2) and forms the Angulata ammonite zone ( Chronozone ). However, this in turn is further subdivided into three subzones, the Schlotheimia extranodosa subzone in the lying wall , the Schlotheimia complanata subzone and the Schlotheimia depressa subzone in the hanging wall . The two upper sub -zones are to be equated with the Marmorea zone in the Alpine region .

The subzones (subchronic zones) are in turn divided into seven bio-horizons (from hanging to lying) according to the following scheme:

  • Schlotheimia depressa
    • Pseudomoreana horizon
    • Depressa horizon
  • Schlotheimia complanata
    • Striatissima horizon
    • Complanata horizon
    • Similis horizon
  • Schlotheimia extranodosa
    • Extranodosa horizon
    • Amblygonia horizon

Angulate layers, Angulate sandstone and Angulate clay

The Angulate layers in north-west Germany and the Angulate sandstone and Angulate clay formations in southern Germany are named after Schlotheimia angulata .

Occurrence

Schlotheimia angulata densicostata

Occurrences of the genus Schlotheimia are found in the Lias of the Swabian Alb , for example near Engstlatt and Mundelfingen . In Baden-Württemberg , Endingen and Vaihingen an der Enz are also worth mentioning . One occurrence in Lower Saxony is Bodenwerder in the Weser Uplands . Sites in North Rhine-Westphalia are Bielefeld , Horn-Bad Meinberg and Oerlinghausen . In Thuringia , the seamounts near Gotha are to be mentioned.

In the Chiemgau Alps , Schlotheimia occurs in the base limestone of the Jura on the west side of the Hochgern . Sites in Austria are in the vicinity of Adnet , on the Fonsjoch near the Achensee , and in the Oberhettangium on the Steinplatte near Waidring . In Switzerland , the cellar clay pit near Frick in Aargau and the sites on the Ferdenrothorn (3180 m) in the canton of Valais are to be cited.

In the northeast of the Paris Basin , Schlotheimia occurs in the hettangium, for example in the province of Luxembourg in the south of Belgium , but also in Luxembourg . In Luxembourg, chimneys appear in the Oberhettangium (above the Grès de Luxembourg ) near Bech , Burmerange , Dalheim , Bad Mondorf and Reckingen / Mess , and even in Ernzen in the southern Eifel ( Rhineland-Palatinate ). In the west of Luxembourg, however, Schlotheimien are below the Grès de Luxembourg near Kapweiler and Schwebach . Stratigraphically of great importance are chimney finds in the Präplanorbis layers of the lower Hettangian, which were encountered in a borehole near Arlon .

In the Netherlands the genus Schlotheimia was found in a salt leaching funnel near Winterswijk . Sites of Schlotheimia are in the United Kingdom in Somerset , at Awre in Gloucestershire and at Portrush in Northern Ireland .

Outside Europe, chimneys appear in British Columbia ( Canada ), in the Pucara Formation near Levanto in Peru and in the New York Canyon in Nevada ( United States ). .

literature

  • WJ Arkell et al .: Mesozoic Ammonoidea. Treatise on Invertebrate Paleontology. Geological Society of America and University of Kansas Press, 1957.
  • W. Lange: The Schlotheimiinae from the Lias Alpha of Northern Germany . In: Palaeontographic . A 100, 1951, p. 1-128 .
  • Raymond C. Moore: Treatise of Invertebrate Paleontology . The Geological Society of America, University of Kansas, Boulder, Colorado 1957, ISBN 0-8137-3112-7 , pp. L235 .

Individual evidence

  1. ^ Jack Sepkoski: A compendium of fossil marine animal genera (Cephalopoda entry) . In: Bulletins of American Paleontology . tape 363 , 2002, p. 1-560 .
  2. ^ Jean Guex, A. Bartolini, V. Atudorei and David Taylor: High resolution ammonite and carbon isotope stratigraphy across the Triassic-Jurassic boundary at New York Canyon (Nevada) . In: Earth and Planetary Science Letters . tape 225 , 2004, pp. 29-41 .
  3. ↑ Jean Guex et al .: Geochronological restraints on post-extinction recovery of the ammonoids and carbon cycle perturbations during the early Jurassic . In: Palaeogeography, Palaeoclimatology, Palaeoecology . tape 346-347 , 2012, pp. 1–11 , doi : 10.1016 / j.palaeo.201204030 .
  4. ^ Gert Bloos and Kevin N. Page: The proposed GSSP for the base of the Sinemurian Stage near East Quantoxhead / West Somerset (SW England) - the ammonite sequence . In: RL Hall and PL Smith: Advances in Jurassic research 2000. Proceedings of the 5th International Symposium on the Jurassic System. (Ed.): GeoResearch Forum . tape 6 , 2002, pp. 13-26 .
  5. ↑ M. Gruner: Dynamic paleoecology and taxonomic treatment of the Lower Jurassic (Hettangian to Lower Sinemurian) on the Swabian Alb . In: Profile . tape 11 . Stuttgart 1997, p. 1-197 .
  6. ^ Avinash C. Mathur: Stratigraphy and depositional environments of the Crinoidal Limestone of Hochgern, Bavarian Alps (Chiemgau) . In: Arquipélago. Série Ciências da Natureza . 1981, p. 103-120 .
  7. ↑ Milos Rakus: Early Liassic Ammonites from the Steinplatte-Kammerköhralm Area (Northern Calcareous Alps / Salzburg) . In: Yearbook of the Federal Geological Institute . 136 issue 4, 1993, ISSN  0016-7800 , p. 919-932 .
  8. ↑ Christian Meister and Bernard Loup: Les gisements d'ammonites du Lias (Hettangien à Pliensbachien) du Ferdenrothorn (Valais, Suisse): analyzes paléontologiques, biostratigraphiques et aspects lithostratigraphiques . In: Eclogae geol. Helv. Band 82/3 , 1989, pp. 1003-1041 .
  9. ↑ AA Klompmaker and BJHM van den Berkmortel: Earliest Jurassic (Hettangian) psiloceratoid ammonites from a pipe at Subrosion Winterswijk, the eastern Netherlands . In: Netherlands Journal of Geosciences - Geologie en Mijnbouw . tape 86-4 , 2007, pp. 379-388 .