Taxonomy and biostratigraphy of Kimmeridgian ammonites from the Kachchh Basin, western India

A collection of 112 Kimmeridgian ammonites, collected bed-by-bed during detailed measurements of four Jurassic sections in the Kachchh Basin are described. They belong to 11 genera of the families Phylloceratidae, Oppeliidae, Ataxioceratidae, and Aspidoceratidae. Some species are considered endemic to the Indo-East-African faunal province, such as Torquatisphinctes alterneplicatus (Waagen), Torquatisphinctes intermedius Spath, Katroliceras katrolensis (Waagen), and Aspidoceras iphiceroides Waagen. A few ammonites, on the other hand, such as Aspidoceras cf. acanthicum (Oppel) and Progeronia digitata (Schneid), have also been recorded from the Mediterranean and/or Submediterranean faunal provinces. Dimorphic pairs in some of the endemic taxa, such as T. alterneplicatus, T. alterneplicatus morph neglecta, T. intermedius, T. acuticostatus Spath, Katroliceras waageni Spath, and Aspidoceras asymmetricum Spath have been recognised. The co-occurrence of north Tethyan guide ammonites with forms endemic to the Indo-East-African faunal province help in refining or corroborating the Kimmeridgian ammonite zonation delineated by earlier workers.