The Aptian ( in the German language also shortened only called Apt, rarely also Aptien ) is in the earth's the name for a chronostratigraphic stage in the upper Cretaceous. It lasted from about 126.3 million geochronological years until about 112.9 million years. The Aptian following the Barremian and is detached from the Albian.
Naming and history
The Aptian is named after the French town of Apt in Provence, near which is the original type locality of the stage. Stage and name were introduced by Alcide Dessalines d' Orbigny 1840.
Definition and GSSP
The beginning of the stage is defined by the base of the magnetic anomaly M0, the end of the first appearance of coccolithophores Type Praediscosphaera columnata. A GSSP (global type locality and type section) have not yet been ratified concluded.
In Tethysbereich the stage is divided into eight ammonite biozones:
- Hypacanthoplites jacobi
- Nolaniceras Nolani
- Parahoplites melchioris
- Epicheloniceras subnodosocostatum
- Duffrenoyia furcata
- Deshayesites deshayesi
- Deshayesites Weissi
- Deshayesites oglanlensis
Locally, divides the stage into two sub-stages Bedoulium and Gargasium.
From the time of the turn of the uppermost Aptian to lowermost Albian in Niger originate remains of up to 12 m long crocodile Sarcosuchus imperator.