The development of the genus Biarmeaspira (Gastropoda) in the Kazanian Paleobasin (Middle Permian, Volga-Urals Region)

Resumo

This paper discusses the morphogenesis and evolutionary history of the genus Biarmeaspira in the Kazanian Paleobasin. Based on an analysis of variability, morphotypes are recognized for B. striata and B. jusupovi, and patterns in the changes of characters are established. The stratigraphic distribution and facies affinity of the species and morphotypes of Biarmeaspira in the Kazanian of the Volga-Urals Region are reviewed.