Phylloceras

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Phylloceras
Taxon of the genus Phylloceras

Taxon of the genus Phylloceras

Temporal occurrence
Hettangium to Maastrichtium
201.3 to 66.0 million years
Systematics
Cephalopods (cephalopoda)
Ammonites (ammonoidea)
Ammonitida
Phylloceratoidea
Phylloceratidae
Phylloceras
Scientific name
Phylloceras
Suess , 1865

Phylloceras is a genus of medium-sized, smooth-skinned, involute (strongly curled) ammonites . It occurs almost worldwide over the entire Jura and Cretaceous .

Initial description and naming

The genus Phylloceras was first described by Eduard Suess in 1865 . Their name is an acronym from the Greek words φύλλον phyllon (leaf) and κέρας keras (horn), where phyllon refers to the leaf-shaped shape of the praised line and keras to the curling in the shape of ram's horns.

Systematics

The genus Phylloceras belongs to the family of Phylloceratidae (subfamily Phylloceratinae ) within the superfamily of Phylloceratoidea . The following taxa are known from her:

Sister genera are Adabofoloceras , Calaiceras , Carinophylloceras , Hantkeniceras , Holcophylloceras , Hypophylloceras , Lepeniceras , Macrophylloceras , Neophylloceras , Partschiceras , Phyllopachyceras , Ptychophylloceras and Zetoceras .

Subgenera are Geyeroceras , Goretophylloceras , Hypophylloceras and Phyllopachyceras .

description

Phragmocones of the genus Phylloceras have an average diameter (D) of 8 to 10 centimeters, rarely up to 20 centimeters. These primitive ammonites are involute and compressed at the sides. Ornaments are almost non-existent, so the shell is practically smooth. The simple growth lines can hardly be seen. The enormously sinuous lines of praise are characteristic of the genus. In a way, their shape is reminiscent of leaves, which explains the name of the genus.

In contrast to other neoammonites, the dimorphism in the genus Phylloceras is only poorly developed.

Way of life

The individuals of the genus Phyloceras were fast- swimming marine carnivores that populated numerous environments, including the open, shallow subtidal , but also the deeper subtidal (with predominantly calciferous basins) and the shelf slope . They were rarely found near the beach or in the deep water area and only rarely in siliciclastic pools, in bio-thermal baths or in submarine compartments .

phylogenesis

It is generally believed that around 201.5 million years ago, shortly before the end of the Triassic genus Psiloceras the top Rhaetian of the Phyllocerataceae had separated. Both taxa survived the extinction of species at the Triassic-Jura border. and then spread into released biotopes . Jean Guex had 1,980 differentiates this prevailing view anything else as the for him Phylloceratidae together with the Juraphyllitidae at the end of Rhäts from the Ussuritidae had developed. The genus Psiloceras had emerged shortly before from the Ussuritidae, which fell victim to the extinction of species . According to this point of view, Psiloceras has developed independently of Phylloceras .

Temporal occurrence

The first taxa of the genus Phylloceras are already known from the Triassic . Phylloceras was one of the very rare ammonite genera that survived the mass extinction at the Triassic-Jura border . The radiation at the beginning of the hettangium should then have originated from it. The genus only became extinct at the Cretaceous-Paleogene border .

Occurrence

Oldest finds of the genus Phylloceras go to back to the Triassic, as in Hungary in the Csövar formation of Karniums . In the Jurassic and the Cretaceous the genus achieved practically a worldwide distribution, fossils from this period come even from the Antarctic .

In Germany , the Phylloceras genus is found in the Jurensis marl of the Toarcium near Bayreuth in Upper Franconia . In North Rhine-Westphalia , the awl formation of the upper campanium near Beckum is to be mentioned. In the Alpine region, finds have been made in the Campan near Bad Tölz . The subgenus Hypophylloceras was discovered in the upper Turonian near Halle and near Rheine in North Rhine-Westphalia.

In Austria , the genus Phylloceras occurs in the Zlambachgraben near Bad Goisern in Upper Austria in the Schnöll formation near Adnet in the state of Salzburg and in the Lienz Dolomites in Tyrol .

literature

  • WJ Arkell et al .: Mesozoic Ammonoidea. Treatise on Invertebrate Paleontology. Geological Society of America and University of Kansas Press, 1957.

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 Guex, David Taylor, Milos Rakus and Hugo Bucher: New data on the phylogeny of Liassic Ammonites . In: Bulletin de la Société Vaudoise des Sciences Naturelles . tape 87.2 , 2000, pp. 109-114 .
  3. ^ Jean Guex: Quelques cas de dimorphisme chez les ammonoïdés du Lias inférieur . In: Bulletin de la Société Vaudoise des Sciences Naturelles . 75 issue 360, 1980, pp. 239-248 .
  4. ^ E. Végh-Neubrandt: Triassic Megalodontaceae - Development, Stratigraphy and Paleontology . Akadémiai Kiadó, Budapest 1982.
  5. ↑ C. Schulbert: The ammonite fauna and stratigraphy of the Mistelgau clay pit near Bayreuth (Upper Franconia) . In: Supplements to the reports of the Natural Science Society Bayreuth eV . tape 4 , 2001, p. 1-183 .
  6. ↑ R. Giers: The United fauna of Mukronatenkreide (lower Obercampan) in the eastern Münsterland . In: Fortschr. Geol. Rheinld. u. Westf. Band 7 , 1964, pp. 213-294 .
  7. ↑ H. Imkeller: The chalk formations and their fauna at the Stallauer Eck and Enzenauer Kopf near Tölz . In: Palaeontographica, (A) . tape 48 . Kassel 1901, p. 1-64 .
  8. ^ Jens Lehmann: Phylloceras (Hypophylloceras) (Ammonoidea) from the Turonian of North Germany . In: Paleontological Journal . tape 69, 3/4 , 1995, pp. 401-407 .
  9. ↑ Milos Rakús: Lower Liassic (Hettangian) ammonites from Zlambach Graben near Bad Goisern, Upper Austria . In: Treatises of the Federal Geological Institute . tape 56 , 1999, p. 329-341 .
  10. ↑ F. Böhm, O. Ebli, L. Krystyn, H. Lobitzer, M. Rakús and M. Siblík: Fauna, Stratigraphy and Depositional Environment of the Hettangian-Sinemurian (Early Jurassic) of Adnet (Salzburg, Austria) . In: Treatises of the Geological Federal Institute Vienna . tape 56 (2) , 1999, pp. 143-271 .
  11. ^ 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 .