Early Jurassic ammonites of the Jura Massif between Bellegarde-sur-Valserine (France) and Delémont (Switzerland)

The ammonite data from 49 localities, with more than 180 described and illustrated taxa, give a good idea of the biodiversity of the ammonite fauna and an overview of the biostratigraphic framework of the western Jura Massif at the Early Jurassic. The 14 biochronozones of the Hettangian, Sinemurian and Pliensbachian, covering a period of about 17 million years, are all represented by ammonites. The stratigraphic ammonite distribution is well defined and correlates well with the horizon sequence established for the Euroboreal domain. A new genus Eteohemimicroceras is described, solving the problem of Hemimicroceras Spath, 1925 – Bifericeras Buckman, 1913.