 |
| Jurassic belemnite jaws: Acrocoelites conoideus & Hibolithes semisulcatus. in Klug, Etter, et al., 2020. Reconstructions by Kenneth De Baets. |
Abstract
Although belemnite rostra can be quite abundant in Jurassic and Cretaceous strata, the record of belemnite jaws was limited to a few specimens from Germany and Russia. Here, we describe and figure three cephalopod jaws from the Middle Jurassic Opalinus Clay of northern Switzerland. Although flattened, the carbonaceous fossils display enough morphological information to rule out an ammonoid, nautiloid or octobrachian origin of the two larger jaws. Their similarities to belemnite jaws from Germany and Russia conforms with our interpretation of these specimens as belemnite jaws. Based on their rather large size, we tentatively assign these two jaws to the megateuthidid Acrocoelites conoideus. The third jaw is a rather small upper jaw of an ammonoid. Since Leioceras opalinum is by far the most common ammonite in this unit in northern Switzerland, we tentatively suggest that the upper jaw belongs to this species.
 |
| Reconstructions of Jurassic belemnite jaws. a–c Acrocoelites conoideus from the Swiss Aalenian. d–f Hibolithes semisulcatus from the German Kimmeridgian, modified after Klug et al. (2010b); the inner lamella of the lower jaw was enlarged |
