Ammonites and Stratigraphy of the Upper Bajocian Garantianagarantiana Zone in the Interfluve between the Kuban and Urup Rivers (Northern Caucasus)

Abstract

This paper presents the results of the study of the Upper Bajocian Garantiana garantiana Zone (Middle Jurassic) and characteristic ammonites in sections of the basin of the Kuban River (Karachay-Cherkessia). The assemblage contains species of the genera Garantiana, Pseudogarantiana, Paragarantiana, Djanaliparkinsonia (all family Stephanoceratidae) and Vermisphinctes (family Perisphinctidae). A section of the Garantiana Zone on the Kyafar River contains (from bottom to top) Beds with Djanaliparkinsonia alanica (also recognized on the Kuban River), Beds with Garantiana subgaranti and Beds with Paragarantiana, approximately corresponding to the Dichotoma, Garantiana, and Tetragona subzones of the standard scale. Garantiana subgaranti Wetzel and Vermisphinctes martiusii (d’Orbigny) are described. Prorsisphinctes Buckman, 1921 is proposed as a junior subjective synonym of Vermisphinctes Buckman, 1920.