CONCLUSIONS

The genus Umiaites was poorly known from the Tithonian of Kutch. A detailed taxonomic revision of the genus has been done, and its precise stratigraphic position has been established. Umiaites is a macroconch, but its microconchiate counterpart has yet to be identified in Kutch. Proniceras has been considered as the possible microconch but the dimorphs do not have overlapping palaeobiogeography. The reasons for this conclusion have been discussed in detail. Similar stratigraphic distribution and contemporaneous extinction has been considered important in establishing dimorphism, and there is growing evidence that dimorphism is apparent in the assemblages of many genera. Our interpretation of the published literature suggests that the macroconch of Umiaites occurs, but was not recognised, in Proniceras assemblages reported from different regions.