Plesioteuthis prisca

Plesioteuthis is among the most common genera of cephalopods from the Solnhofen Limestone, and several exceptional specimens have allowed researchers to reconstruct, in good detail, the anatomy of its soft parts (Donovan & Fuchs, 2016; Klug et al., 2015). This extinct cephalopod had eight arms like an octopus, two pairs of fins, and an internal rigid support structure made of chitin (called a gladius), similar to that of a cuttlefish (Klug et al., 2015). This particular specimen consists mostly of the well-preserved gladius, even though in preparing the fossil, someone took license to engrave a hypothetical outline of the arms and fins. There are, however, hints of soft parts preservation, such as transverse striations perpendicular to the long axis of the body, which typically represent phosphatized musculature (see bottom left image), and mineralizations of calcite that commonly form in the arm-head complex, around the mouth area, separate from the gladius and without any preserved anatomical detail (Hoffmann et al., 2020a).

We can infer that small ammonites and fish were part of the diet of these predators, as remains of these organisms have been found in the stomach contents of fossil Plesioteuthis (Hoffmann et al., 2020b). In turn, Plesioteuthis was likely preyed upon by pterosaurs, as evidenced by a pterosaur tooth embedded in the fossilized tissues of a Plesioteuthis specimen (Hoffmann et al., 2020a).

Plesioteuthis fossils have been found in Jurassic rocks of Germany and Cretaceous rocks of Germany and Lebanon (Paleobiology Database, n.d.).

Transverse striations, hinting at soft parts preservation.

References:

Donovan, D.T. and Füchs, D., 2016. Fossilized soft tissues in Coleoidea, Treatise Online, 73, Part M, Chapter 13. pp. 1-30. doi:10.17161/to.v0i0.5675.

Hoffmann, R., Bestwick, J., Berndt, G. et al., 2020. Pterosaurs ate soft-bodied cephalopods (Coleoidea). Scientific Reports. 10(1), p.1230. doi:10.1038/s41598-020-57731-2

Hoffmann, R., Stevens, K., Keupp, H., Simonsen, S. and Schweigert, G., 2020. Regurgitalites–a window into the trophic ecology of fossil cephalopods. Journal of the Geological Society, 177(1), pp. 82-102. doi:10.1144/jgs2019-117.

Klug, C., Fuchs, D., Schweigert, G., Röper, M. and Tischlinger, H., 2015. New anatomical information on arms and fins from exceptionally preserved Plesioteuthis (Coleoidea) from the Late Jurassic of Germany. Swiss Journal of Palaeontology, 134, pp. 245-255. doi:10.1007/s13358-015-0093-y.

Paleobiology Database, No date. Plesioteuthis. Available at: https://paleobiodb.org/classic/basicTaxonInfo?taxon_no=15970. (Accessed: January 2025).