Molluscan fauna from the Miocene sediments of Kachchh, Gujarat, India - Part 3. Gastropods

Systematic description of 25 gastropod species from the Khari Nadi Formation (Aquitanian) and Chhasra Formation (Burdigalian) from the Kachchh District, Gujarat, India is given. A checklist of 116 forms including those reported by earlier researchers, emending taxonomic identifications wherever necessary, is also provided. Vredenburg had referred these two formations together as 'the Gaj Beds of Kachchh'. He noticed the affinity of molluscs among the Miocene deposits of Kachchh and Kathiawar regions of Gujarat, and Sind province of Pakistan. He also observed that molluscs from his 'Lower Gaj' and 'Upper Gaj' Formations showed relationship respectively with the Rembang (Aquitanian) and Njalindung (Burdigalian) series of the East Indies. Aquitanian and Burdigalian ages assigned by him were later substantiated by Raju on the basis of foraminifera. Present studies corroborated that the molluscan assemblage from the Miocene rocks of Kachchh is closely related to that from the Gaj Beds of Sind and the Ashapura Clay Member of Kathiawar; besides revealing that the fauna from these three formations taken together is essentially endemic. Discovery of certain species from the Quilon Beds in the Miocene of Kachchh evinces a close affinity between these two formations. The present fauna includes five extant forms, while 29 forms have related species in the Recent fauna.