An infrazonal ammonite-based biostratigraphy for the Kimmeridgian of Spitsbergen is reviewed in detail. The Bauhini Zone, bayi horizon, aff. beaugrandi and norvegicum horizon have been recognized in this area for the first ...

A collection of ammonites of the genus Amoeboceras located carefully in the section of Nordvik Peninsula in northern Siberia has enabled recognition of the standard Boreal ammonite zones of the Upper Oxfordian ...