New data on systematic composition of Early Triassic ammonoids from the Shimanskyites shimanskyi Zone of The Kamenushka River basin, South Primorye and their phylogenetic and stratigraphic significance

New information has been obtained regarding the systematic composition of ammonoids and conodonts from the Shimanskyites shimanskyi Zone of the lower (Smithian) Substage of the Olenekian Stage in South Primorye. This is based on the material from the Lower Triassic sections of the Kamenushka River basin, specifically from the Kamenushka-2 and Perevalny sections. In light of the correlation data pertaining to these sections, it is proposed that the Scythogondolella milleri conodont Zone in this region corresponds to two ammonite zones (Anasibirites nevolini and Shimanskyites shimanskyi) of the Smithian Substage in South Primorye. The new species of the genera Owenites (O. golozubovi sp. nov.) and Preflorianites (P. lelikovi sp. nov.) are described herein. The clarification and emendation of the diagnosis of the genus Submeekoceras, in conjunction with the results of its comparison with other genera of the family Arctoceratidae, permit a reconsideration of the generic affiliation of the majority of forms currently attributed to the genus Arctoceras. The obtained results make it possible to outline the phylogenetic relationships of a number of genera belonging to the families Lanceolitidae and Ussuritidae (order Prolecanitida Miller et Furnish, 1954), as well as Proptychitidae and Arctoceratidae (order Ceratitida Hyatt, 1884). The prevalence of diverse ostracod species in the Shimanskyites shimanskyi Zone, coupled with a relatively diverse ammonoid community, suggests that anoxia, which is assumed to have been present in other marine basins in other regions of the world at that time, was absent in the bottom waters of the late Smithian sea marine basin of South Primorye.