ABOUT THE IDENTIFICATION OF PARAMEXICOCERAS BEDS OF THE UPPER PERMIAN CHANGHSINGIAN STAGE IN THE SOUTHERN VERKHOYANIE

In the lower part of the Nekuchan Formation of the Dyba River basin, an accumulation of Paramexicoceras aldanense shells was discovered. The discovery of Paramexicoceras aldanense in the Changhsingian Stage of the Dyba River basin radically changes ideas about the age and stratigraphic position of this species, and also sheds light on the solution to the global Late Permian extinction of biotas. This find allowed the question of the settlement of ammonoid communities during the period to attribute the indicated cyclolobids to the Changhsingian Stage, and to isolate the host sediments into layers with Paramexicoceras aldanense , underlying the Otocerasconcavum zone.