Ammonites of Tethyan Origin in the Ryazanian Stage of the Russian Platform: Genera Transcaspiites Luppov and Karasyazites gen. nov.

Resumo

This paper presents the results of the study of ammonites of the family Himalayitidae from the Surites spasskensis Zone of the Ryazanian Stage of Central Russia. The new taxa Transcaspiites tscheffkini sp. nov., T. transitionis sp. nov., and Karasyazites gen. nov., with the type species Subalpinites bajarunasi Luppov, are described. The hypothesis that Transcaspiites Luppov originated from the genus Riasanites Spath is proposed. The analysis of the taxonomic composition of ammonites allows the Neocosmoceras–Septaliphoria semenovi regional zone of Mangyshlak to be correlated with the Spasskensis zone of the standard scale of the Ryazanian Stage.