Bajocian | |
Color: | Bajocian |
Time Start: | 170.9 |
Time Start Uncertainty: | 0.8 |
Time End: | 168.2 |
Time End Uncertainty: | 1.2 |
Timeline: | Jurassic |
Name Formality: | Formal |
Celestial Body: | earth |
Usage: | Global (ICS) |
Timescales Used: | ICS Time Scale |
Chrono Unit: | Age |
Strat Unit: | Stage |
Timespan Formality: | Formal |
Lower Boundary Def: | FAD of the Ammonites Hyperlioceras mundum, Hyperlioceras furcatum, Braunsina aspera, and Braunsina elegantula |
Lower Gssp Location: | Cabo Mondego, Portugal |
Lower Gssp Accept Date: | 1996[1] |
Upper Boundary Def: | FAD of the Ammonite Gonolkites convergen |
Upper Gssp Location: | Ravin du Bès, Bas-Auran, Alpes de Haute, France |
Upper Gssp Accept Date: | July 2008[2] |
In the geologic timescale, the Bajocian is an age and stage in the Middle Jurassic. It lasted from approximately 170.9 ±0.8 Ma to around 168.2 ±1.2 Ma (million years ago). The Bajocian Age succeeds the Aalenian Age and precedes the Bathonian Age.[3]
The Bajocian Stage takes its name from the Latin name (Bajocae) of the town of Bayeux, in the region of Normandy in France. The stage was named and introduced in scientific literature by French palaeontologist Alcide d'Orbigny in 1842.
The base of the Bajocian stage is defined as the place in the stratigraphic column where fossils of the ammonite genus Hyperlioceras first appear. A global reference profile (a GSSP) for the base is located at Murtinheira, close to Cabo Mondego in Portugal.[4] The top of the Bajocian (the base of the Bathonian) is at the first appearance of ammonite species Parkinsonia convergens.
The Bajocian is often divided into Lower/Early and Upper/Late subages or substages.
In the Tethys domain, the Bajocian contains seven ammonite biozones: