A new ammonoid biochronological zonation for the Dienerian of the Northern Indian Margin is constructed, with 12 zones

We propose to subdivide the Dienerian into three parts (early, middle and late) instead of two

Ammonoids underwent a moderate recovery in the early Dienerian followed by low diversity before the early Smithian recovery

Low diversity in mid-late Dienerian is associated with anoxic conditions and warm temperatures

mid-late Dienerian times now appear as a distinct extinction phase in the Early Triassic recovery