Cénomanien

The Cénomanien , also called Woodbinian , is the stratigraphic first stage Crétacé superior. It extends between -99,6  My (+ 0,9) and -93,5  My (+ 0,8). Cénomanien represents more the marine high level of the 600  last million years (approximately 150  m with the top of the current level).

Stratotype

Cénomanien owes its name at the French city of the Mans, in the the Sarthe, and more particularly with the former people of the Cénomans.

Its biostratigraphic base is defined by the first appearance of the Foraminifère Rotalipora globotruncanoides . Its top corresponds to the first appearance of the Ammonite Watinoceras devonense .

Cénomanien and the Turonien constitute a key stage in the development of the Squamate S (snakes, lizards). Between the beginning of Cénomanien and the end of Turonien, four great groups diversify in the zone méditerranéenne :

  • the snakes " with pattes" (reaching 1,5  m and all pachyostotic S, which one finds only with the cénomanien in Western Europe, North Africa, Adriatic area and the Middle East),
  • the Dolichosaure S,
  • the Aigialosauridé S
  • the Mosasauridé S
These two last are gathered under the term of Mosasauroidea. Some think that the origin of the snakes goes up at that time.

See too

sources

  • http://paleopolis.rediris.es/cg/CG2007_M02/CG2007_M02_Abstract05.html
----

Random links:Serge Dassault | Épipactis of the marshes | BRS (Barry Rogliano Rooms) | Esbjörn Svensson Trio | Canada' S Wonderland | Calendrier_celtique