Viséan ammonoids from South Urals

Abstract

Two occurrences of Visean ammonoids in the Ural Mountains form the basis for this paper. In the Kzyl-Shin Gorge on the Kiya river, Aktiubinsk province, a bed of gray fragmental limestone, 1 m thick, has yielded the following genera: *Prolecanites, *Pronorites, Beyrichoceras, *Nomismoceras, *Girtyoceras, Trizonoceras, Arcanoceras, and *Goniatites. Also, east of the village of Novosamarskaya on the Sakmara river, Orenburg province, a black limestone block contains the genera marked with an asterisk (*) in the list above, together with Kazalchoceras. The Kzyl-Shin assemblage is of particular interest because it includes Beyrichoceras, generally not found with Goniatites this high in the Carboniferous section. Based on the Goniatites, assignable to the group of G. crenistria Phillips, and other components, the assemblage is dated as very late Visean. It probably is equivalent to the bottom part of the Caney Shale of Oklahoma that contains Girtyoceras meslerianum (Girty) and Goniatitesmultiliratus Gordon. The ...