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In sections of the Achdorf Formation at the Wochenberg hill (western Swabian Alb, SW Germany), a succession of five ammonite biohorizons is distinguished (from bottom to top): the crassicostatum and viallii biohorizons of the Lower Aalenian (Bifidatum Subzone, Opalinum Zone) and the latiumbilicus, discoidea α and discoidea β biohorizons of the Upper Aalenian (Murchisonae Subzone, Murchisonae Zone). The herein newly introduced viallii biohorizon is the youngest hitherto identified biohorizon of the Opalinum Zone (Bifidatum Subzone). A lectotype is designated for Staufenia latiumbilicus (Quenstedt, 1886), the index ammonite of the latiumbilicus biohorizon. The succession of biohorizons of the Murchisonae Subzone reflects the evolution of the graphoceratid late Aalenian ammonite genera Staufenia and Ludwigia.

In 1953, Hara provided new combinations for many sectional and species names when he combined Jussiaea L. with Ludwigia L., and at the time, Ludwigia sect. Oligospermum (Micheli) H.Hara was the correct name for one well-defined section. However, subsequent changes to/clarifications of the botanical code have necessitated a change for that name in that now an autonym is treated as having priority over the name or names of the same date and rank that established it. Since Hara's combination was based on Jussiaea sect. Oligospermum Micheli, the correct name for this section is Ludwigia sect. Jussiaea (L.) Hoch, W.L.Wagner, & P.H.Raven.

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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.