Structure and phylogenetic significance of Trachyteuthis (Coleoidea) from the Kimmeridge Clay of England

Abstract

SUMMARY The large and rare coleoid cephalopod Trachyteuthis is found within the lithographic limestones of the German Lower Tithonian and the contemporaneous bituminous shales of the Kimmeridge Clay Formation. Complete shells are apparently confined to the more anoxic facies. The occurrence of francolitic Trachyteuthis and Actinosepia with aragonitic molluscan shells in the Kimmeridge Clay (Upper Jurassic) and Pierre Shale Formations (Upper Cretaceous), underlines the lack of biological affinity between the Mesozoic Trachyteuthididae and their homeomorphs the Tertiary cuttlebones ( Sepia and Belosepia ).