Ammonoid Stratigraphy of the Spiti Shale Formation in Spiti Himalaya, India

Ammonoid biostratigraphy of the Spiti Shale Formation is being discussed in light of new data. Their systematics supported by stratigraphic details of the collected ammonoids have resulted in the organization of a set of 9 distinct successive ammonoid assemblages ranging in age from Oxfordian to Berriasian i.e. from 154 Ma to 130 Ma. The chronostratigraphically significant Jurassic/Cretaceous System and Kimmeridgian/Tithonian Stage boundaries have been identified. The ranges of species of Spiti Shale ammonoids are presented here for the first time.