Издатель: ПИН РАН , Место издания: М. , Год издания: 2024

The history of the establishment (introduction), morphology, composition and distribution of ammonoids of the family Sirenitidae Tozer, 1971 is presented. T he resu!ts of the revision of the Carnian sirenitids of Northeast Asia аге discussed, which made it possible to identify the main direction of evolution of the lineage Seimkanites → Yakutosirenites (Vozinites) armiger → У (Yakutosirenites) pentastichus → Orientosirenites yakutensis → O. bytschkovi, originating from the Arpaditidae. In young forms, this consists of the earlier арреаrаnсе and disappearance of ornamentation in ontogeny, in аn increase in the terminal diameter, involution of the shell and complexity of the suture. The morphology of the internal whorls of this group has Ьееп found to differ fгom that of the nominal genus Sirenites Mojsisovics, 1893, which is widespread in sections of Northeast Asia in the ирреr Lower Carnian. T he absence of a median ventral groove and а different character of the ribs in Sirenites confirm its phylogenetic relationship with the Early Carnian Trachyceratidae and indicate heterogeneity in the composition of Carnian sirenitids of Northeast Asia in the modern sense. The lineage Seimkanites → Yakutosirenites → Orientosirenites, which separated from the arpaditids and developed for а long time in the Carnian in bоrеаl paleobasins, needs to bе raised, after additional studies, to the rank of either а new subfamily оr а new family.