Bajocian

The Bajocian ( to Bajoc rarely shortened, also Bajocien ) is the second chronostratigraphic stage of the Middle Jurassic series in the Jura. The Bajocian began geochronological before about 170.3 million years ago and ended about 168.3 million years and therefore lasted about 3.9 million years.

Naming and history

The original type locality is located in Bayeux (Dept. Calvados, France). The stage is named after the Gallo-Roman city name Bajocae for Bayeux. And stage name was introduced by Alcide Dessalines d' Orbigny, 1842.

Definition and GSSP

The beginning of the stage is defined by the first appearance of the ammonite genus Hyperlioceras. The purpose determining GSSP ( = type locality and type profile ) is Murtinheira at Cabo Mondego in Portugal. The end is marked by the first appearance of the ammonite species Parkinsonia convergent.

Subdivision of the Bajocian

The Bajocian is subdivided in the Tethyan region in seven ammonite biozones:

  • Parkinsonia parkinsoni
  • Garantiana Garantiana
  • Strenoceras niortense
  • Stephanoceras humphriesianum
  • Sonninia propinquans
  • Witchellia laeviuscula
  • Hyperlioceras discites

The Bajocian is in turn divided into Unterbajocium and Oberbajocium, with the first appearance of the ammonite Strenoceras niortense the beginning of the Oberbajociums sets.

Mya (unit) Oxfordian (stage) Pliensbachian
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