Jaws of a large belemnite and an ammonite from the Aalenian (Middle Jurassic) of Switzerland.

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.

Parasitoid biology preserved in mineralized fossils.

About 50% of all animal species are considered parasites. The linkage of species diversity to a parasitic lifestyle is especially evident in the insect order Hymenoptera. However, fossil evidence for host-parasitoid interactions is extremely rare, rendering hypotheses on the evolution of parasitism assumptive.