Coleoid beaks from the Nusplingen Lithographic Limestone (Upper Kimmeridgian, SW Germany)

Abstract

Over twenty specimens of coleoid beaks were recovered from the Nusplingen Lithographic Limestone (Upper Jurassic, Late Kimmeridgian, Beckeri Zone, Ulmense Subzone; SW Germany). Based on their morphology, four forms of lower beaks and three forms of upper beaks can be distinguished among the finds. Two gladii of Trachyteuthis hastiformis are associated with a complete beak and hence enable taxonomic assignment of two beak forms. In one of the two specimens, the beaks are still articulated. A third specimen shows another form of upper and lower beak on one slab, which is tentatively interpreted as the beak elements of Plesioteuthis prisca. The largest type of upper beak probably belongs to Leptotheuthis based on its scarcity and size. The remaining two forms are of uncertain taxonomic affiliation. The lower beak of Trachyteuthis resembles that of Recent Octopus and thus suggests a close phylogenetic relation to the Octopoda, as the lower beak of Vampyroteuthis has a different morphology. These originally partially chitinous structures were discovered in the Fossillagerstatte of Nusplingen because the bituminous sediments still contain a significant portion of the original organic matter. This might be the case because of a low permeability of the respective strata. Otherwise, without the color contrast, these delicate structures would hardly be discernible against the carbonate matrix.