Tithonian

The Tithonian ( in German often shortened to Tithonian, rarely also Tithonien, referred to 1990 in part as a Portlandium ) is the highest stratigraphic level of the Jura and geochronological lasted from about 152.1 to about 145 million years ago. The Tithonian following the Kimmeridgian and Berriasian from, the lowest level of the Lower Cretaceous, detached.

Naming and history

The " Tithonian " was introduced in 1865 by Albert Oppel. The name of the Tithonian goes back to Tithonus, a figure from Greek mythology. Tithonus was the husband of Eos, the goddess of the dawn, comparable to the Tithonian, which is closely connected with the beginning of the Cretaceous.

Definition and GSSP

The stage begins hybonotum with the ammonite zone of Hybonoticeras and ends with the onset of the Ammonites Berriasella jacobi. A GSSP (global type locality and type profile ) has not yet been determined.

Subdivision

In the Tethyan region, the Tithonian is divided into seven ammonite biozones:

• Durangites
• Micracanthoceras micranthum
• Micracanthoceras Pontian / Burckardticeras peroni
• Semiformiceras fallauxi
• Semiformiceras semi forme
• Semiformiceras darwini
• Hybonoticeras hybonotum

There is a further subdivision of the stage in a Lower, Middle and Upper Tithonian, the latter corresponds to the Portlandian in England.

Faziesausbildung

In the area of ​​marine deposits of the Tethys the Tithonian is designed as a calcareous facies with a typical Kopffüßerfauna. From the Tithonian of Germany ( Solnhofen limestone ) the fossils of the " first bird " Archaeopteryx and thus the geologically oldest evidence for the evolution of birds originate.