Aalenian

The Aalenian ( German shortened Aalen, also Aalenien ) is in Earth's history, a chronostratigraphic stage of the Jura and geochronological covers the period from about 174.1 to 170.3 million years ago. This stage precedes the Toarcian; you follow the Bajocian.

Naming and history

The stage is named after the city of Aalen in Baden -Württemberg. The stage and the name has been used for the first time by Karl Mayer- Eymar 1864. The first fossil discoveries were made tunnels in Aalen in the depths among others. Of this, a large part of the urban Urweltmuseum Aalen is issued.

Definition and GSSP

The beginning of the stage is defined by the first appearance of the ammonite genus Leioceras. The first appearance of the ammonite genus Hyperlioceras marks the end of the stage. For "Global Stratotype Section and Point" ( GSSP: corresponds to about one type profile ) profiles 500 m north of the village Fuentelsaz ( province of Guadalajara, Spain) was determined.

Subdivision of the Aalenian

The Aalenian is subdivided in Tethysbereich in the following ammonite biozones:

  • Graphoceras concavum
  • Brasilia bradfordensis
  • Ludwigia Murchisonae
  • Leioceras opalinum
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