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Jain, Sreepat (2021): Immigration of the genus Macrocephalites Spath and the Bathonian biostratigraphy of the Kachchh basin (Western India, South Tethys). In: Zitteliana, Vol. 94: pp. 3-36
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Abstract

The Bathonian occurrences of Indonesian Macrocephalites from the Kachchh basin (Western India) (and correspondingly the immigration of the genus into the basin) is evaluated in context of improved biostratigraphy and new ammonite data vis-à-vis European and Submediterranean records. The Indonesian Middle Bathonian macrocephalitids [Macrocephalites bifurcatus transient intermedius (Spath) (M), M. bifurcatus transient cf. intermedius (Spath) (M), M. bifurcatus transient aff. bifurcatus Boehm (m) and M. cf. etheridgei Spath (m)], have largely been recorded from a single dome, Jumara (from the basal Yellow bed, bed A4), with additional singular occurrences of M. cf. etheridgei Spath (m) from the adjoining Nara and Jhura domes (Kachchh). In Jumara, the Indonesian macrocephalitids are associated with Micromphalites (Clydomphalites) clydocromphalus Arkell (M), Procerites (Gracilisphinctes) arkelli Collignon (M), P. (G.) intermedius Jain (m), P. hians (Waagen) (M), Wagnericeras sp. (m), Parapatoceras distans (Baugier and Sauzé) (M), Sivajiceras congener (Waagen) (M and m), Macrocephalites triangularis Spath (M and m), Epimorphoceras decorum (Waagen) (M), and Reineckeia sp. A and B (M). This fauna is correlated with the European early Middle Bathonian Progracilis Zone. Both Jumara and the adjoining Jara domes have also yielded characteristic Indonesian Late Bathonian macrocephalitids – M. cf. keeuwensis Boehm (M and m), M. keeuwensis var. aff. forma flexuosa Boehm (m) and M. cf. mantataranus Boehm (M). In light of improved high–resolution stratigraphy, the Kachchh Bathonian fauna is evaluated and an improved biostratigraphy of the basin is proposed.