Dactylioceras

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Dactylioceras
Dactylioceras sp. from the German Jura, diameter 4 cm

Dactylioceras sp. from the German Jura, diameter 4 cm

Temporal occurrence
Toarcium to the end of Toarcium
182.7 to 174.1 million years
Locations
Systematics
Primordial mouths (protostomia)
Molluscs (molluscum)
Cephalopods (cephalopoda)
Ammonites (ammonoidea)
Dactylioceratidae
Dactylioceras
Scientific name
Dactylioceras
Hyatt , 1867

Dactylioceras is a genus from the extinct group of ammonites characterized by medium-sized, very developed (evolute) housing. It is assigned to the Toarcium , a chronostratigraphic level of the Lower Jurassic , and is considered a key fossil .

First description and etymology

The genus Dactylioceras was first separated in 1867 by the zoologist and paleontologist Alpheus Hyatt as a separate subgroup of the ammonites. Historical representations and descriptions go back to the end of the 16th century , for example with Johann Bauhin .

The name of the ammonite is derived from the Greek terms δάκτυλος (dáktylos) "finger" and κέρας (kéras) "horn". "Finger" refers to the finger-like branching of the ribs.

morphology

The morphological description of the phragmocone is flat-disc serpenticon to kadicon with a very slow increase in turns. The case size of a Dactylioceras ranges from 25 mm to 150 mm, but rarely exceeds 100 mm. The thin-walled shell is rarely preserved. The dominant form is an evolute shape (N = 0.52 to 0.60) with a cross-oval to highly oval winding cross-section. The wall around the wall is usually systematically designed and can be divided into numerous sections. In most forms, the umbilical surface, which rises vertically or steeply from the seam, is followed by a pronounced umbilical edge. The subsequent flank extends to the external edge, the actual shape being different depending on the type.

The normal sculpture is formed from forked ribs, single ribs and switching ribs, which run without interruption to the outer edge and lead into so-called rib cleft points, depending on the type also with developed, small knots, which are usually located on the outer edge of the flank. The intercostal space between the ribs is often 1.5 to 2 times the rib width. The actual course of the ribs is an essential characteristic of taxonomy .

Aptychs are not known in the genus Dactylioceras . Neither constrictions nor mouth apophyses are formed.

The subgenus Dactylioceras (Eodactylites) is characterized by strongly splayed external ribs, their winding cross-section is square to rectangular with an attached roof. The subgenus Dactylioceras (Orthodactylites) has no splayed external ribs and its cross-section is rounded, the sculpture overall much finer. Characteristic of the subgenus Dactylioceras (Dactylioceras) is their differentiated, sharp and regular rib pattern. Their flank ribs are considerably stronger than the external ribs and run rectoradiat or proradiat, while the external ribs are proclinic. The rib density is usually looser than that of Dactylioceras (Orthodactylites) .

Way of life

Dactylioceras was a predatory ammonite genus that probably stalked its prey on the sea floor. Mass deaths are quite common in it and it is believed that such events occurred immediately after hatching. The dead housings were washed up to form Schill banks on the edge of the Jurassic Sea. Experiments in current tanks indicated that Dactylioceras was very likely just a slow swimmer. The genus held predominantly in Kalkmeeren in shallow to deeper Subtidal on, but was also the shelf ramp encountered and sub-sea subjects. With regard to changes in the oxygen and salinity of the sea water, the genus Dactylioceras probably only had a low tolerance (meso- to steno-oxybiont and meso- to steno-halin).

Taxonomy

Dactylioceras commune from Yorkshire

Reinhard Schmidt-Effing gave a historical overview of the taxonomy of the Dactylioceratidae family in 1972, in which he demonstrated that the systematics of the fossils in question have undergone constant changes since Alpheus Hyatt, primarily by J. Buckman, William Joscelyn Arkell and Otto Heinrich Schindewolf has been. This fact is reflected in a very high number of synonyms (see below).

Subgenera and species

Axel von Hillebrandt and Reinhard Schmidt-Effing gave the following classification in 1981:

Further systematics name additional species with the inclusion of Simpson 1843 and 1855 .

Dactylioceras commune from the Posidonia slate from Holzmaden , diameter 8 centimeters. The phragmocone is accompanied by small microcones (bottom left).

The following taxa are known from the subgenus Dactylioceras (Dactylioceras) :

The sister taxa are Catacoeloceras , Collina , Nodicoeloceras , Peronoceras , Porpoceras , Reynesoceras , Septimaniceras and Zugodactylites .

The following synonyms are now established from the genus Dactylioceras :

  • Anguidactylites Buckman , 1926
  • Arcidactylites Buckman , 1926
  • Athlodactylites Buckman , 1927
  • Curvidactylites Buckman , 1927
  • Dactylioceras (Eodactylites) Schmidt-Effing , 1972
  • Eodactylites Schmidt-Effing , 1972
  • Koinodactylites Buckman , 1927
  • Leptodactylites Buckman , 1926
  • Microdactylites
  • Nomodactylites Buckman , 1927
  • Parvidactylites Buckman , 1927
  • Peridactylites Buckman , 1926
  • Planicoeloceras Venturi and Ferri , 2001
  • Rakusites Guex , 1971
  • Simplidactylites Buckman , 1927
  • Toxodactylites Buckman , 1926
  • Vermidactylites Buckman , 1926
  • Xeinodactylites Buckman , 1926

phylogenesis

Dactylioceras semicelatum from Hondelage

According to H. Frebold (1922), the genus Dactylioceras is said to descend directly from the Lytoceratinae via Prodactylioceras . However, this hypothesis is not accepted by paleontologists like Otto Heinrich Schindewolf . According to Braga Alarcon (1983), the first indeterminable representatives of the genus Dactylioceras go back to the middle domerium and are likely to have split off from the sister genus Reynesoceras . This is also controversial.

Schmidt-Effing (1972) sees the subgenus Dactylioceras (Eodactylites) in the higher domerium derived from the genus Coeloderoceras , which in turn was derived from the genus Coeloceras from the Psiloceratoidea . In his opinion, the family Dactylioceratidae is rooted with Coeloderoceras (and possibly with Coeloceras ) in forms around Microderoceras , whereby the splitting off of Microderoceras should already have taken place during the Obtusum Zone in the Upper Sinemurium within the Mediterranean Fauna Province .

From Dactylioceras (Eodactylites) then developed successively Dactylioceras (Orthodactylites) and Dactylioceras (Dactylioceras) .

According to Otto Schindewolf, all post-Lassian Ammonitina are derived from the Dactylioceratidae.

Index fossil

The genus Dactylioceras is the index fossil of the lower Toarcium in the Tenuicostatum zone named after Dactylioceras (Orthodactylites) tenuicostatum and in the slightly higher Bifrons zone (after Hildoceras bifrons ). The serpentine zone in between , according to Hildoceras serpentinum , also has representatives of the genus Dactylioceras , but their subzones are named after other ammonite genera .

The tenuicostatum zone consists of four sub-zones (from hanging wall to lying ):

  • Semicelatum subzone according to Dactylioceras semicelatum
  • Tenuicostatum subzone according to Dactylioceras (Orthodactylites) tenuicostatum
  • Clevelandicum subzone after Dactylioceras clevelandicum
  • Paltum subzone according to Protogrammoceras paltum

The Clevelandicum subzone is divided into two biozones with the horizons Dactylioceras crosbeyi in the lying wall and Dactylioceras clevelandicum in the hanging wall . The tenuicostatum subzone with Dactylioceras (Orthodactylites) tenuicostatum is not further subdivided. The semicelatum subzone also consists of two biozones with the horizons Dactylioceras semicelatum at the base and Tiltoniceras antiquum in the top.

The Bifrons zone is made up of three sub-zones (from hanging to lying ):

The commune subzone is divided into three biozones with the horizons Ovaticeras ovatum at the base, followed by Dactylioceras commune and above Dactylioceras athleticum .

Lithological name

Rock units named after Dactylioceras are, for example, the Dactylioceras conglomerate of the Altdorf marble or Dactylioceras banks in the Posidonia schist formation of the southern German Lias (for example near Schlaifhausen or Weißenburg in Bavaria).

Age position

The genus Dactylioceras appears for the first time around 186 million years ago with the subgenus Dactylioceras (Eodactylites) in the Spinatum Zone (but possibly also in the Margaritatus Zone ) of the Middle Domerium in the fossil record . The subgenus Dactylioceras (Orthodactylites) did not appear until 183 million years before the end of the Pliensbachian . Both subgenera then persist until the beginning of the Bifrons zone (Commune subzone) in the Middle Toarcium, whereby Dactylioceras (Eodactylites) already become quite rare from the Falcifer zone of the Lower Toarcium. The subgenus Dactylioceras (Dactylioceras) occurs for the first time from the tenuicostatum zone of the middle sub-toarcium and expires around 177 million years in the variabilis zone of the upper middle toarcium. The genus Dactylioceras thus existed for almost 10 million years.

Occurrence

Dactylioceras (Orthodactylites) helianthoides from Japan

Dactylioceras are found worldwide, especially in northwestern Europe , but also occur in North America (for example in southern Alaska in the Talkeetna Formation , in Alberta near Edson , in British Columbia on the mainland at Harrison Lake , near Hazelton , Nelson , on the Taseko Lakes and on the Queen Charlotte Islands and in the north of the Yukon including Whitehorse ), further in east Greenland and in north and east Siberia (for example in Sichote-Alin ). At the level of the sub-genera and species there are, however, geographical differentiations.

Scientifically described sites of further Dactylioceratidae in South America are the Chilean high cordillera between 26 ° and 29 ° south latitude

In the area of ​​the Tethys , the northern Spain in Álava , the Celtiberian chain in the areas around Burgos , Logroño , Teruel and Saragossa and also the Betides of southern Spain, Morocco , Algeria , on the Djebel Zaghouan in Tunisia , Sicily and the rest of Italy with occurrences at Taormina , in the Bugarone Formation in the Apennines of the Marche as well as in the Southern Alps , Yugoslavia , the Bakony Forest and the Gerecse Mountains in Hungary , western Bulgaria , near Pirot in Serbia , Greece , Turkey , the Carpathian Mountains , the Caucasus , Indonesia , Nagato in Japan and New Zealand .

The Djebel Zaghouan from the east, site of Lassian ammonites in Tunisia

As for the north-eastern European fauna province, there are sites of the genus Dactylioceras in Germany near Dotternhausen , Hechingen and Holzmaden in Baden-Württemberg , Altdorf near Nuremberg , Gunzenhausen , Kässwasser near Heroldsberg , Kalchreuth , Schnaittach , Wassertrüdingen and Ostheim near Weißenburg in Middle Franconia , Buttenheim , Mistelgau , Schlaifhausen and Unterstürmig near Forchheim in Upper Franconia , Amberg and Freudenberg in the Upper Palatinate (all Bavaria ) and Cremlingen , Hondelage near Braunschweig , Rottorf am Klei and Wolfsburg in Lower Saxony .

In France , the genus appears at Charleville-Mézières in the Ardennes department , in Burgundy , at Millau in the Causses , at Feuguerolles in the Calvados department , at Airvault and Mauzé-Thouarsais in the Deux-Sèvres department , near Teyjat in the Sèvres department , in the Département Département . in Poitou as well as at Chantonnay , Le Bernard , Jard-sur-Mer , Péault , Pissotte and Saint-Hilaire-la-Forêt in the Vendée department and Ligugé in the Vienne department .

In England , in addition to deposits in Lincolnshire (drilling at Nettleton ) and Ilminster in Somerset, the finds from Kettleness , Port Mulgrave , Saltwick and Whitby in Yorkshire are worth mentioning.

literature

  • Reinhard Schmidt-Effing: On the palaeontology of Jurassic invertebrates. The Dactylioceratidae, an ammonite family of the Lower Jurassic . Systematics, stratigraphy, zoogeography, phylogeny with a special focus on Spanish material. In: Münster research on geology and palaeontology . No. 25/26 . Münster 1972 ( ashipunov.info [PDF; accessed on September 23, 2014]).
  • Axel von Hillebrandt; Reinhard Schmidt-Effing: Ammonites from the Toarcian (Jura) of Chile (South America): The species of the genera Dactylioceras, Nodicoeloceras, Peronoceras and Collina . In: Dietrich Herm (ed.): Zitteliana . Treatises of the Bavarian State Collection for Paleontology and Historical Geology. No. 6 . Bavarian State Collection for Paleontology and Historical Geology, 1981, ISSN  0373-9627 .

Individual evidence

  1. ^ Paleobiology Database , accessed September 21, 2012
  2. ↑ Sepkoski's Online Genus Database , accessed September 21, 2014
  3. ↑ Lexicon of Biology: Ammonoidea. Retrieved September 21, 2014 .
  4. ↑ Reinhard Schmidt-Effing : On the paleontology of Jurassic invertebrates. 1972, p. 6 . , referring to: A. Hyatt, The fossil cephalopods of the Museum of Comparative Zoology , in: Bulletin of The Museum of Comparative Zoology, vol. 3, pp. 59-111, Cambridge, Mass. 1872.
  5. ↑ Rudolf Schlegelmilch : The ammonites of the southern German Lias . 2nd Edition. Gustav Fischer Verlag , Stuttgart 1992, ISBN 3-437-30678-2 , p. 87 .
  6. ↑ Reinhard Schmidt-Effing: On the paleontology of Jurassic invertebrates. 1972, p. 21-25 .
  7. ↑ Reinhard Schmidt-Effing: On the paleontology of Jurassic invertebrates. 1972, p. 35-40 .
  8. ↑ Axel von Hillebrandt; Reinhard Schmidt-Effing: Ammonites from the Toarcian (Jura) of Chile (South America) . 1981, p. 31-41 .
  9. ↑ Rudolf Schlegelmilch : The ammonites of the southern German Lias . 2nd Edition. Gustav Fischer Verlag , Stuttgart 1992, ISBN 3-437-30678-2 , p. 87 f .
  10. ^ The Genus Dactylioceras Ammonoidea from Northeastern Russia. Retrieved September 28, 2014 .
  11. ↑ H. Frebold: Phylogeny and Biostratigraphy of the Amaltheen in the middle Lias of northwest Germany . In: Jber. Niedersächs. geol. Ver. tape 15 . Hanover 1922, p. 1-26 .
  12. ^ JC Braga Alarcon: Ammonites del Domerense de la zona Subbética (Cordilleras Béticas, Sur de España). - PhD thesis . Universidad de Granada, 1983, pp. 410 .
  13. ↑ Otto Heinrich Schindewolf : Studies on the tribal history of the ammonites . In: Akad. Wiss. Lit., depending on math.-nat. Kl. Born 1968, 3. Mainz 1968, p. 733-901 .
  14. ^ GK Jakobs: Toarcian (Early Jurassic) ammonoids from western North America . In: Geological Survey of Canada, Bulletin . tape 428 , 1997, pp. 137 .
  15. ^ AJ Arthur, PL Smith, JWH Monger and HW Tipper: Mesozoic stratigraphy and Jurassic paleontology west of Harrison Lake, southwestern British Columbia . In: Geological Survey of Canada Bulletin . tape 441 , 1993, pp. 1-62 .
  16. ^ PL Smith and HW Tipper: Pliensbachian (Lower Jurassic) ammonites of the Queen Charlotte Islands, British Columbia . In: Bulletins of American Paleontology . tape 108 (348) , 1996, pp. 1-122 .
  17. ↑ T .P. 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 .
  18. ^ ME Clapham: Lower to Middle Jurassic Stratigraphy and Ammonite Fauna of the Northern Whitehorse Trough, Yukon, Canada . In: Unpublished BS Thesis . 2000, p. 1-86 .
  19. ^ A. Rosenkrantz: The Lower Jurassic Rocks of East Greenland Part 1 . In: Meddelelser Om Gronland . tape 110 (1) , 1934, pp. 4-122 .
  20. ↑ II Sey and AD Kalacheva: Biostratigraphy of the Lower and Middle Jurassic deposits of the Far East . "Nedra" Publisher, Leningrad 1980.
  21. ↑ Reinhard Schmidt-Effing: On the paleontology of Jurassic invertebrates. 1972, p. 59 .
  22. ↑ Reinhard Schmidt-Effing: On the paleontology of Jurassic invertebrates. 1972, p. 143 .
  23. ↑ Axel von Hillebrandt; Reinhard Schmidt-Effing: Ammonites from the Toarcian (Jura) of Chile (South America) . 1981, p. 6th f., 31 .
  24. ↑ 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 Jurassic . tape 7 , 2009, p. 37-45 .
  25. ↑ M. Raku and J. Guex: Les ammonites you jurassique inférieur et moyen de la dorsal tunisienne . In: Mémoires de Géologie (Lausanne) . tape 39 , 2002, p. 1-149 .
  26. ↑ A. Fucini: Fossili domeriani dei Dintorni di Taormina . In: Palaeontograph. Ital. tape 26 . Pisa 1935, p. 75-116 .
  27. ↑ S. Sassaroli and F. Venturi: n Cingolites gene, a new lower Toarcian Hildoceratinae (Ammonitina) from the Marchean Apennines (Cingoli, Macerata, Italy).. . In: Bollettino della Società Paleontologica Italiana . tape 49 , 2010, p. 97-118 .
  28. ^ B. Géczy and C. Meister: Les ammonites du Domérien de la montagne du Bakony (Hongrie) . In: Revue de Paléobiologie . tape 17 (1) , 1998, pp. 69-161 .
  29. ^ Z. Kovács: Lower Toarcian Ammonitida fauna and biostratigraphy of the Gerecse Mountains (Hungary) . In: Fragmenta Palaeontologica Hungarica . tape 29 , 2011, p. 1-48 .
  30. ^ LS Metodiev: The Ammonite zones of the Toarcian in Bulgaria - New evidence, subzonation and correlation with the standard zones and subzones in North-Western Europe . In: Comptes rendus de l'Academie bulgare des Sciences . tape 61 , 2008, p. 87-132 .
  31. Jump up ↑ J. Jankicevic, D. Rabrenovic and V. Radulovic: Stratigrafske i paleontoloshke karakteristike Lijasa u Zabrdju (Stara Planina) [Stratigraphic and palaeontological characteristics of the Liassic of Zabrde (Stara Planina)] . In: Geoloski Anali Balkanskoga Poluostrva . tape 47 , 1983, p. 161182 .
  32. ↑ K. Tanabe: Early Jurrasic Macrofauna of the Oxygen-Depleted Epicontinental Marin Basin in the Toyora Area, West Japan . In: Saito Ho-on Kai Special Publication . tape 3 , 1991, pp. 147-161 .
  33. ↑ Reinhard Schmidt-Effing: On the paleontology of Jurassic invertebrates. 1972, p. 17-19, 143 f .
  34. ^ W. Riegraf: Biostratigraphy, fauna and micropalaeontology of the Untertoarcium profile of Unterstürmig (Upper Franconia, southern Germany) . In: Geological sheets for Northeast Bavaria . tape 34/35 , 1985, pp. 241-272 .
  35. ↑ Pascal Neige and Isabel Rouget: Les ammonites du Toarcien de Chantonnay (Vendée, France): analyze paleontologique, biostratigraphie et réflexion sur les Hildoceratinae . In: Geodiversitas . tape 24 (4) , 2002, pp. 765-784 .
  36. ↑ J. Gabilly: Evolution et systématique des Phymatoceratinae et des Grammoceratinae (Hildocerataceae Ammonitina) de la région de Thouars, stratotype du Toarcien . In: Mémoires de la Société Géologique de France, Nouvelle Série . tape 124 , 1976, pp. 1-1196 .
  37. ^ Marc Bécaud: Le Toarcien de la bordure sud et sud-est du Massif armoricain (Deux-Sèvres et Vendée) . In: Le Naturaliste Vendéen . N ° 2, 2002, p. 3-33 .

Web links

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