The Maastrichtian ( often shortened to the German Maastricht) is in Earth's history, the highest and most recent chronostratigraphic stage of the Upper Cretaceous. The stage includes in absolute terms ( geochronological ) the period from about 72 to about 66 million years ago. The Maastrichtian follows the Campanian, it is detached from the Danian ( formerly placed in the Cretaceous ), the oldest stage of the Paleogene and thus the Cenozoic ( Cenozoic ).
At the end of the Maastrichtian is the Cretaceous-Tertiary boundary, which documents one of the largest global mass extinction of Earth's history and an associated dramatic Faunenschnitt.
Naming and history
Named the stage is after the Dutch city of Maastricht. Stage and name were proposed by André Dumont 1849.
Definition and GSSP
The base is defined by the first appearance of the ammonite species Pachydiscus neubergicus, the upper limit is marked by an iridium anomaly, which is also correlated with a mass extinction of various animal groups ( Foraminifera, Calcareous nannoplankton, dinosaurs, ammonites, belemnites, etc.). The GSSP is located in the Grande Carrière, Tercis -les- Bains, Landes, South West France ( coordinate: 43 ° 40 ' 46.1 " N, 1 ° 6' 47.9 " W43.679472222222 - 1.1133055555556 ).
Two sub- stages are provided for the Maastrichtian: lower and Obermaastrichtium
In Tethysbereich the Maastrichtian is divided into three ammonite zones ( from young to old):
- Anapachydiscus terminus
- Anapachydiscus fresvillensis
- Pachydiscus neubergicus to Pachydiscus epiplectus
Fauna and flora development
With the Maastrichtian the Cretaceous and thus the Mesozoic era ends. The following period is the Paleogene, which is already expected to Cenozoic. The turn of the Cretaceous to Paleogene is called Cretaceous-Tertiary boundary for the beginning of the Cenozoic after the older term " tertiary ". This is characterized by a mass extinction, where a large part of that animal and plant life was destroyed. The cause of the impact (Impact) is suspected of a large meteorite or extremely strong volcanism. The Cretaceous-Tertiary boundary also coincides with a strong marine retreat (marine regression). This meant that large shelf areas were dry, which were still covered in the Campanian and early Maastrichtian of shallow seas, and so disappeared the habitat of many residents of the flat water.