Postcranial Osteoderms of Late Permian Pareiasaurs from Eastern Europe. I. Chronology of Localities

To clarify the chronological sequence of East European localities of late Permian pareiasaur osteoderms, we carried out a stratigraphic analysis of the osteoderm-bearing strata. Thirty localities have been dated with maximum accuracy. They characterize eight successive stratigraphic levels: Vanyushonkian, Syominian, and Kichugian beds of the Putyatinian Regional Stage (Upper Severodvinian), Chizhian and Rovdinian beds of the Bykovian Regional Stage (Lower Vyatkian), Aristovian and Gorokhovetsian beds of the Nefyodovian Regional Stage (Upper Vyatkian), and Lagernian Beds of the Zhukovian Regional Stage (Upper Vyatkian).