The Genus Delphinites Sayn (Ammonoidea: Neocomitidae) in the Lower Valanginian of the Russian Platform

Abstract

This paper presents the results of the revision of the taxonomic composition and stratigraphic distribution of Central Russian representatives of the Valanginian genus Delphinites. The lower Undaloplicatilis zone of the Valanginian in the basin of the Sura River (Menya River) contains D. undulatoplicatilis (Stchirowsky) [subjective synonyms: Oxynoticeras tuberculiferum Stchirowsky, Pseudogarnieria securis Sasonova], D. menensis (Stchirowsky), D. alatyrense (Kemper), D. kurmyschensis (Stchirowsky), D. stchirowskyi (Sasonova), D. donovani Alsen et Rawson and D. heineae sp. nov. In addition, Delphinites sp. was figured from the Michalskii Zone (terminal Lower Valanginian) of the Kostroma Region (Unzha River). Thus, the interval of distribution of the genus Delphinites is not restricted by the basal zone of the Valanginian.