Zitteliana A 54 (2014) 91 The Arkelli Chronozone: A new early Middle Bathonian standard ammonite zone for Kachchh, western India (southern Jurassic Tethys) Sreepat Jain Zitteliana A 54, 91 – 135 München, 31.12.2014 DG-2, Flat 52D, SFS Flats, Vikaspuri, New Delhi – 110018, India E-mail:
[email protected] Manuscript received 16.06.2014; revision accepted 28.07.2014 ISSN 1612 - 412X Abstract Based on the widespread distribution of the nominal and Madagascan ammonite species Procerites (Gracilisphinctes) progracilis arkelli Collignon [M] in Kachchh (western India), a new early Middle Bathonian Arkelli Chronozone is proposed and correlated with the Western European early Middle Bathonian Progracilis Zone. The nominal species is now firmly established as a geographic subspecies of the Western European P. (G.) progracilis Cox and Arkell [M]. The recorded assemblage within the Kachchh Mainland from this chrono- zone now contain Micromphalites (Clydomphalites) clydocromphalus Arkell [M], Procerites hians Waagen [M], Procerites (Siemiradzkia) cf. verciacensis [m], Sivajiceras congener (Waagen) [M and m], Procerites (Gracilisphinctes) progracilis arkelli Collignon [M and m], P. (G.) progracilis aff. arkelli Collignon [M], P. (G.) intermedius n. sp. [m], Macrocephalites cf. etheridgei Spath [m], M. bifurcatus transient aff. bifurcatus Boehm [m], M. bifurcatus transient intermedius (Spath) [M and m], M. bifurcatus transient cf. intermedius Boehm [M], Macroce- phalites triangularis Spath [M and m], Parapatoceras distans (Baugier and Sauzé) [M], Reineckeia sp. A and B [M] and Eutrephoceras sp. [M]. Coeval sediments at the Island Belt had previously yielded the presence of Procerites cf. schloenbachi, Micromphalites (Clydompha- lites) cf. clydocromphalus, M. (Clydomphalites) sp. indet., M. aff. hourcqui, Clydoniceras triangulare, C.