Amaltheus
| Amaltheus | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Amaltheus sp. |
||||||||||||
| Temporal occurrence | ||||||||||||
| Lower Jurassic | ||||||||||||
| 185.7 to 184.1 million years | ||||||||||||
| Locations | ||||||||||||
|
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Amaltheus | ||||||||||||
| de Montfort , 1808 | ||||||||||||
Amaltheus is a genus of ammonites from the Lower Jura . It is a key fossil in the Upper Pliensbachian ( Domerium ) in the Margaritatus zone namedafter Amaltheus margaritatus .
First description and etymology
The genus Amaltheus was first described scientifically in 1808 by the French naturalist Pierre Dénys de Montfort . The name is derived from the nymph Amaltheia , who was raised by Rhea's son Zeus as a nurse transformed into a divine goat.
characterization
The genus Amaltheus consists of small to medium-sized oxyconic ammonites reaching up to 25 centimeters with only a moderately open umbilicus (oxyconic housings are flat, disc-shaped and have a keel-shaped, pointed back). A very special feature among ammonites is their longitudinally arranged color stripes of the phragmocone . With N = 0.25 to 0.33, the genus is neither particularly involute (narrow-naveled) nor evolutionary (wide-naveled). A rather sharp, rope-shaped (funiliform) keel runs around the vent, which is characteristic of the genus. The ribs, which are not particularly clear, are slightly sigmoidal. There is no reinforcement in adult Amaltheus margaritatus , but all other taxa have tubercles or even spines. Constrictions also occur in several taxa. In general, the development of the Amaltheidae is from V-shaped, oxyconic winding cross-section to reinforced forms with a rectangular winding cross-section. The line of praise consists of a short external lobe, a large and long lateral lobe, a small, secondary lateral lobe and auxiliary lobes that are gradually drawn back near the umbilical.
Systematics
The genus Amaltheus 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 of the genus Amaltheus are known:
- Amaltheus angulatus
- Amaltheus bifurcus Howarth, 1958
- Amaltheus bondonniensis master, 1986
- Amaltheus clevelandicus Young and Bird
- Amaltheus depressus Simpson
- Amaltheus gibbosus Schlotheim , 1820
- Amaltheus gloriosus Hyatt , 1867
- Amaltheus laevigatus Howarth
- Amaltheus margaritatus de Montford , 1808
- Amaltheus nodifer Buckman
- Amaltheus salebrosum Hyatt, 1867
- Amaltheus sp.
- Amaltheus stokesi Sowerby , 1818
- Amaltheus subnodosus Young and Bird, 1828
- Amaltheus viligaensis Tuchkov, 1954
- Amaltheus Wertheri Lange, 1932
Synonyms are Nordamaltheus Repin, 1968 and Proamaltheus Lange, 1932 .
Amauroceras and Pleuroceras act as sister taxa .
The genus is divided into two sub-genera, the above-mentioned representatives of Amaltheus (Amaltheus) and the sub-genus Amaltheus (Pseudoamaltheus) Frebold, 1922 . The latter is often viewed as a separate genus. It developed from Amaltheus (Amaltheus) relatively late and lost the keel and ribs early on.
It is assumed that the Amaltheidae family developed from the Liparoceratidae via the genus Oistoceras at the beginning of the Upper Pliensbachian .
Shortly before the end of the Pliensbachian there was a significant global cooling caused by glacial factors, so that the Amaltheidae penetrated into the Tethys area. With the subsequent extinction of species on the Pliensbachium / Toarcium border, however, the Amaltheidae became extinct.
Ammonite zone
The genus Amaltheus is a key fossil and defines the fourth ammonite zone of the Pliensbachian, the Margaritatus zone . The Margaritatus Zone follows the Davoei Zone and is in turn overlaid by the Spinatum Zone . It is divided into three sub-zones (from hanging to lying ):
- Stokesi subzone according to Amaltheus stokesi
- Subnodosus subzone according to Amaltheus subnodosus
- Gibbosus subzone according to Amaltheus gibbosus
Way of life
The individuals of the genus Amaltheus were probably very fast swimming marine carnivores that populated the shallow as well as the deeper calcareous subtidal far away from the coast and followed drifting plankton . They were also occasionally to be found in the open, deep shelf area and over underwater fans.
Amaltheenton Formation
The Amaltheenton formation in the southern German Jura region was named after the Amaltheus genus, which occurs quite frequently in it .
Occurrence
The occurrences of Amaltheus in Germany are quite numerous, for example at Aalen , Achalm , Eningen , Pliensbach and Reutlingen in Baden-Württemberg , Kalchreuth and Moritzberg in Middle Franconia , Buttenheim and Eggolsheim (Unterstürmig) in Upper Franconia , Ehenfeld in Upper Palatinate ( Bavaria ), near Beierstedt , Gebhardshagen , Rottorf and Wohld in Lower Saxony and near Bielefeld , Hellern near Osnabrück and Velpe in North Rhine-Westphalia . In Austria , the genus can be found in the Adnet formation in the province of Salzburg .
The occurrences in France are also very numerous and often pyritized , so the genus appears in the Ardennes department southwest of Sedan , in the Ariège department , in the Aveyron department near Millau , in the Bas-Rhin department near Lixhausen , in Normandy near Fresnay-le-Puceux in the Calvados department , in the Haute-Marne department , in the Indre department , in the Vendée department near Bessay , Jard-sur-Mer and near Péault, and in the Vienne department near Champagné-Saint-Hilaire and Ligugé . Many sites are particularly in Burgundy , in the Causses , such as Rivière-sur-Tarn and Saint-Étienne-du-Valdonnez and in the French Jura. Find sites in England are next to Charmouth and Seatown in Dorset Gloucestershire , Somerset and the Yorkshire coast . In Scotland , the genus Amaltheus appears on the Hebridean island of Raasay . In Italy , the Generoso Basin of the Lombard Alps is to be mentioned.
In Poland , the genus Amaltheus was encountered while drilling in northwest Pomerania.
Amaltheus is also found in the Pontic Fauna Province of Turkey , at Köserelik-Kizik in the Tokat Province . In Iran , the Shemshak group in the Elburs should be listed .
In North Africa, the genus appears near Oujda in eastern Morocco , in western Algeria and on Jebel Zaghouan in Tunisia (Tunisian ridge).
Find sites in North America are the Arctic Alaska , Alberta in Canada and the Stikinia Terran .
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 . No. 393 , 2018, p. 1-84 ( priweb.org [PDF]).
- Raymond Cecil Moore : Treatise on Invertebrate 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
- ↑ JJ Sepkoski: A compendium of fossil marine animal genera . In: Bulletins of American Paleontology . tape 363 , 2002, p. 1-560 .
- ↑ Pierre Dénys de Montfort: Conchyliologie systématique, et classification méthodique des coquilles: offrant leurs figures, leur arrangement générique, leurs descriptions caractéristiques, leurs noms; ainsi que leur synonymie en plusieurs langues; ouvrage destiné à faciliter l'étude des coquilles, ainsi que leur disposition dans les cabinets d'histoire naturelle. Coquilles univalves, cloisonnées. Tomes premier et second, Paris. Schoell, Paris 1808.
- ^ Henry Härtinger: Cross-border commuters on the A 39? The fauna at the transition from the Lower to the Upper Pliensbachium . tape 36 . Paleontology Working Group Hanover, 2008, p. 113-121 .
- ^ FA Wittler and R. Roth: Fauna and biostratigraphy in the Lias gamma / delta border area southwest of Lotte near Osnabrück (Jura, NW Germany) . tape 31 . Paleontology Working Group Hanover, 2003, p. 14-30 .
- ^ Christian Meister and F. Böhm: Austroalpine Liassic Amonites from the Adnet Formation (Northern Calcareous Alps) . In: Yearbook of the Federal Geological Institute . A 136, 1993, p. 163-211 .
- ↑ Jean-Louis Dommergues et al: Les ammonites du Pliensbachien et du Toarcien basal dans la carrière de la Roche Blain (Fresnay-le-Puceux, Calvados, Basse-Normandie, France). Taxonomy, implications stratigraphiques et paleobiogéographiques. In: Revue de Paléobiologie . tape 27-1 . Muséum d'Histoire Naturelle de la ville de Genève, 2008, p. 265-329 .
- ^ Grzegorz Pienkowski: The first Early Jurassic ammonite find in central Poland . In: Volumina Jurassica . XII (1), 2014, pp. 99-104 .
- ↑ K. Seyed-Emami et al .: Lower and Middle Jurassic ammonoids of the Shemshak Group in Alborz, Iran and their palaeobiogeographical and biostratigraphical importance . In: Acta Paleontologica Polonica . Vol. 53, No. 2 . Instytut Paleobiologii PAN, 2008, p. 244 .
- ↑ Milos Rakus and Jean Guex: Les ammonites du Jurassique inférieur et moyen de la dorsale tunisienne . In: Mémoires de Géologie (Lausanne) . No. 39 , 2002, ISSN 1015-3578 , p. 109 .