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In March and April 2018, the 10th International Symposium Cephalopods—Present and Past (ISCPP) was held in Fes, Morocco. Meeting and the post-conference fieldtrip were organized by representatives of the Westfalische Wilhelms-Universitat, Munster, the Mohammed V University of Rabat and Hassan II Academy of Sciences and Technology, the University Sidi Mohammed Ben Abdellah, Fes, University Hassan II, Casablanca, and the University of Zurich. We dedicate this proceedings volume to the memory of Prof. Dr. Jurgen Kullmann, who passed away in 2018.

Sigurd von Boletzky was a cephalopod researcher who was world-renowned for his enthusiasm for his field of research, for his friendly and calm personality, and, of course, his publications. He dedicated most of his life as active researcher on the development, biology and evolution of coleoids. Nevertheless, he was always curious to learn about other cephalopods as well. Sigurd passed away in Switzerland on September 28th 2020. We dedicate this text and volume to his memory.

Accumulations of ammonoid shell fragments have been recovered from the Hangenberg Black Shale (latest Devonian) of the southern Maider (eastern Anti-Atlas, Morocco). They are here interpreted as regurgitalites and ascribed tentatively to gnathostomes as possible tracemakers. The recognition of fossil regurgitations is reviewed and a checklist provided.

The impact of increasing atmospheric COThe online version contains supplementary material available at 10.1186/s13358-022-00246-2.

Trace fossils occur in several strata of the Devonian and Carboniferous of the eastern Anti-Atlas, but they are still poorly documented. Here, we describe a fossil swimming trace from strata overlying the Hangenberg Black Shale (correlation largely based on lithostratigraphy; Postclymenia ammonoid genozone, ca. 370 Ma old). We discuss the systematic position of the tracemaker and its body size. This ichnofossil is important for three main reasons: (1) it is considered here to be the first record of Undichna from the Devonian of Gondwana, as far as we know; (2) it is the oldest record of vertebrate trace fossils from Africa; (3) it provides a unique window into the behaviour of Late Devonian fishes for which body-fossils cannot provide direct evidence. Further, we put this discovery into the macroecological context of the palaeoenvironment following the Late Devonian Hangenberg biodiversity crisis.

The genus Basiloceras gen. nov. containing the two species B. goliath sp. nov. and B. david sp. nov. is described. It belongs to the Acleistoceratidae within the Oncocerida. Both species are from the Middle Devonian of the Tafilalt (Morocco). The genus exhibits a large interspecific size range between the small Eifelian B. david sp. nov. and the Givetian B. goliath sp. nov., the largest Devonian oncocerid currently known, altogether only second to some fragmentary remains of Calchasiceras from the Carboniferous of Russia. Several other large species are mainly known from the late Emsian of Bohemia and the Eifelian of Germany. The holotype of B. goliath sp. nov. contains numerous epicoles, trace fossils and shell debris, which are discussed in the context of its taphonomy. Compared to other oncocerids, Basiloceras is characterised by a short body chamber, which might be related to buoyancy regulation. In contrast to some older publications, we do not regard breviconic oncocerids with contracted aperture as benthic or nektobenthic animals, but instead, we think that they dwelled in the water column.

Two specimens of the Late Mississippian ammonoid cephalopod Metadimorphoceras sp. were recovered from the Bear Gulch Limestone in Montana. This unit was deposited in the lowest part of the Big Snowy Basin, where the bottom waters are thought to have been strongly oxygen deficient. The two nearly equally sized specimens are impressions with soft tissues preserved as brown carbonaceous smears. Diagenetic processes destroyed their aragonitic shells. The preserved soft tissues are interpreted as mandibles, remains of food in the crop, and, possibly, ovaries and eyes. The specimens are on their sides, aperture-to-aperture, and probably the male is on the left and the female is on the right. The specimens are thought to have been in the process of copulation when they died. Copulation by most (all?) externally shelled cephalopods (extinct ammonoids and fossil and extant nautiloids) was probably in a head-to-head, aperture-to-aperture position. This was probably governed in part by restricted accessibility to the female reproductive organs due to the presence of the shell and the ability of both animals to partly withdraw into their shells during copulation. The shell protected them from predators during copulation. In coleoids, which lack an external shell, copulation is a more rapid affair due to the greater vulnerability from predators including other coleoids. We suggest that the fossils from the Bear Gulch Limestone and similar finds of paired ammonoids preserved together with interlocking apertures, and including soft parts in the body chamber, represent examples of ammonoid behavior frozen in time. The two ammonoids were probably too pre-occupied with copulation to notice that they were sinking into the hypoxic bottom waters of the basin and facing suffocation (distraction sinking).

The Alpstein (northeastern Switzerland) has yielded a relatively high diversity of Cretaceous macrofossils. Here, new discoveries of invertebrate fossils from a new locality of the early to late Albian age in Semelenberg (northeastern Alpstein, canton St. Gallen) are documented. In spite of the very small size of these samples and the 1-m-thick, very condensed section, the locality yielded four ammonite species that are here documented for the first time from Switzerland. One of these species is new and Eoscaphites kuersteineri sp. nov. is introduced as new taxon. We also investigated the paleoecology of the middle to late Albian of this region based on the abundant macrofossils. The alpha diversity at Semelenberg is very similar to that of a previously documented fauna from several localities in the northeastern Alpstein region of similar age, which are located 2–10 km west of Semelenberg. A minor discrepancy is rooted in the proportion of benthic organisms, which may indicate slight differences in bathymetry between Semelenberg and the previously studied locality (northeastern Alpstein).