Record of a new species of Erymnoceras Hyatt, 1900 (Ammonoidea) from the Middle Jurassic of eastern Kutch, India and its stratigraphic and evolutionary significance

摘要

A new species of Erymnoceras, Erymnoceras washtawaensis sp. nov., from Wagad, eastern Kutch is described. The genus is a time-diagnostic fleeting taxon and is found elsewhere only from the upper Middle Callovian. This record allows a precise dating of the Middle Callovian sequence in this region, which in turn assists intra- and interprovincial correlation. Evolution of Erymnoceras from Subgrossuvria is envisaged, and Kutch is believed to be the centre of origin.