Ladinian
The Ladinian ( in German language, usually shortened to Ladin ) is in the Earth's upper stratigraphic stage of the Middle Triassic, the geochronological the period before about 242 corresponds to about 235 million years, and thus took about 8.3 million. The previous stage is the Anisian, the following stage, the Carnian, which already belongs to the Upper Triassic.
Naming and history
The stage was proposed by Alexander Bittner 1892 and named after the ethnic group of the Ladin.
Definition and GSSP
The beginning of the stage is defined by the first appearance of the ammonite species Eoprotrachyceras curionii. The border to Karn has not yet been finally determined. Probably the boundary is defined by the first appearance of the ammonite genera Daxatina or Trachyceras, and the first appearance of the conodont species Metapolygnathus polygnathiformis. The GSSP (global type locality and type profile ) is located in the riverbed of Caffaro, in Bagolino (Brescia Province, Italy).
Subdivision
The Ladinian is divided into four ammonite zones:
- Frechites regoledanus zone
- Protrachyceras Archelaus Zone
- Protrachyceras gredleri zone
- Eoprotrachyceras curionii zone
Regionally, the Ladin in the lower grades Fassan ( Fassanium = lower two ammonite zones) and Longobard ( Longobardium = upper two ammonite zones) is divided.