APTYCHI FROM THE VOLGIAN STAGE OF THE RUSSIAN PLATFORM

Abstract

Volgian aptychi from the Russian Platform are described and figured for the first time. The Lower Volgian klimovi Zone and the uppermost Kimmeridgian beds contain Lamellaptychus submortilleti Trauth, 1938. The pseudoscythica Zone (Faunal Horizon neoburgense) contains Laevaptychus latobliquus Trauth, 1931, belonging to Anaspidoceras neoburgense (Oppel, 1863), and a small unidentifiable Lamellaptychus sp. A new species Praestriaptychus volgensis was found in the panderi Zone (Middle Volgian). Probably, these aptychi belong to the Boreal-Subboreal Virgatitinae or Dorsoplanitinae, because they are accompanied by numerous Pavlovia and Zaraiskites. The occurrence of P. volgensis is the youngest find of Praestriaptychus in the Jurassic.