Ammonoids from the upper part of the Otoceras Beds of the Induan Stage in Northeastern Russia are studied for the first time. The species Otoceras suolicum sp. nov. and O. biakovi sp. nov., represented by small shells, are described from the Lower Nekuchan Subformation on the right bank of the Setorym River (Southern Verkhoyanie), above the distribution interval of the zonal species Otoceras boreale Spath. Otoceras suolicum is morphologically close to the significantly older Otoceras gracile from the Otoceras concavum Zone of Arctic Canada, and probably the two species form a lateral branch in the evolution of Boreal Otoceras. Otoceras biakovi most likely separated from O. boreale, acquiring a more complex suture and a stepped-conical shape of the umbilicus. The renewal of the ammonoid species composition revealed, suggests separation of the upper part of the former Otoceras boreale Zone. This part is now proposed for consideration as an independent biostratigraphic unit-the Otoceras biakovi Beds.
