Conference Agenda

Inoceramid material from the Lachman Crags Member of the basal Santa Marta Formation (James Ross Island) was collected during the Czech Antarctic scientific expeditions in years 2009-2013. Fieldworks were conducted c. 2500 m SSW of the Czech Antarctic Station on the NW slopes of Lachman Crags, northern James Ross Island. The succession was sampled and analysed for calcareous nannofossils and foraminifers.

The inoceramids are dominated by the ‘Inoceramus’ steinmanni – ‘Inoceramus’ pacificus group, accompanied by juveniles of ?‘Inoceramus’ australis, rare ‘Inoceramus’ aff. andinus, and single Platyceramus sp. and ‘Inoceramus’ sp. A specimen assignable to the Cordiceramus mitraikyensis group constrains the assemblage to the upper Santonian–basalmost Campanian.

Calcareous nannofossils from the A90 section were poorly preserved, etched and mostly fragmented with the exception of small specimens of genera Biscutum, Prediscosphaera, and Discorhabdus. They indicate an interval from the first occurrence of Broinsonia parca expansa (UC9c zone) to the last occurrence of Eiffellithus eximius (UC15 Zone) that spans from the uppermost Turonian to the Campanian.

Microfossil taphocoenoses contain a low-diversity, low-abundance benthic foraminiferal community. Agglutinated foraminifera are represented by Haplophragmoides spp. and Spiroplectammina vagaensis, while calcareous benthics include Gavelinella sandidgei, Planularia sp., Pyrulina sp., Hemirobulina sp., and Quadrimorphina sp.

The presence of ‘Inoceramus’ neocaledonicus in the underlying Hidden Lake Formation—apparently equivalent of the late Coniacian ‘Inoceramus’ africanus of Madagascar—suggests a stratigraphic gap at the base of the Santa Marta Formation.

The inoceramid assemblage reflects the Weddellian Biogeographic Province, but with distinct connections to the East African bioprovince.

The revised edition of "Fossilien aus dem Campan von Hannover" (Schneider & Girod, 2023) provided a comprehensive overview, but revealed numerous undescribed gastropods. Consequently, this gastropod revision project has begun.

Key challenges included unreliable old literature, drawings, stratigraphy, and incomplete knowledge of references. We also addressed type species, new sampling, and collection access (including private ones). Our collection-based research analyzed ~8,000 specimens (32,000 photos) necessitating multiple publications.

Beyond Campanian gastropods, our investigation included Maastrichtian and Santonian species to gain evolutionary insights, leading to the development of higher taxonomic hypotheses. Pterocerellidae and Xenophoridae serve as illustration of our findings:

Gene sequencing has revealed a close relationship between the Xenophoridae and Aporrhaidae, despite their markedly different morphologies (Irwin et al., 2024). Our discovery of new Acanthoxenophora species exhibiting long spines on the last whorl echoes a pattern observed in the Jurassic genus Diempterus and the Lower Cretaceous "Murex calcar". This shared characteristic suggests a novel hypothesis regarding their evolution.

The Pterocerellidae, a group of aporrhaid-like species with a widespread Cretaceous distribution, are represented by six distinct lineages in the boreal European fauna. Our analysis has led to a more consistent taxonomy of this group.

References

Irwin, A. R., Bouchet, P., Crame, J. A., Harper, E. M., Kronenberg, G. C., Strong, E. E., & Williams, S. T. (2024). Molecular phylogenetics of the superfamily Stromboidea (Caenogastropoda): New insights from increased taxon sampling. Zoologica Scripta, 53(6):818-838.

Schneider, C. & Girod, P. (eds) 2023. Fossilien aus dem Campan von Hannover, 4. Auflage; Hannover: AP-H; pp. 712.

Finn Surlyk and Anne M. Sørensen

Department of Geosciences and Natural Resource Management

University of Copenhagen

Øster Voldgade 10

1350 Copenhagen K

Denmark

Well-exposed rocky shores and their associated faunas are rare in the geological record. A prominent example is Ivö Klack in southern Sweden a small Campanian island at the northern margin of the Late Cretaceous Chalk Sea. The fauna is the richest ancient rocky shore fauna known, with about 260 shell-bearing invertebrate species and about 70 vertebrate species, including 3 birds inhabiting the shoreline and the adjacent waters. The preserved fauna provides information on virtually all trophic levels in the ecosystem and offers an unparalleled opportunity for reconstruction of the ecosystem. Six trophic levels are recognized based on modes of life, feeding strategies, diets, and preferred habitats of the individual species. The ecosystem matches modern analogues in terms of richness. This is quite remarkable for a fauna, which lived about 77.5 myr ago. However, this to some extent reflects that the richness of the fauna is time averaged over about 500 kyr, but stratigraphic changes in faunal composition have not been observed. The reconstructed ecosystem thus gives a unique picture of the life on and around an ancient rocky shore.

A total of 158 terminal Maastrichtian deep-sea sediment samples (IODP Exp. 342, Site U1403, palaeo-water depth 3,600 m) yielded 850 atelostomate (spatangoid, holasteroid) and cidaroid spine fragments, plus a spine type that cannot be assigned to any echinoid group. Hollow, non-verticillate spines with a large lumen and a thin cylinder show narrowly spaced, low septae, bearing irregularly distributed thorns. Ovate, elongated pores between the ridges perforate the cylinder. Comparably voluminous, hollow lumen, thin cylinders and thorned septae occur in the Diadematacea (Diadematoida, Micropygoida). Because most Diadematoida spines are verticillate, and thorn-bearing spines of Micropygoida have a meshwork-filled lumen, Diadematacea are no likely source. Hollow spines occur also in the Echinothuriacea (Pedinoida, Aspidodiadematoida, Echinothurioida), but Pedinoida spines are more solid and weakly serrated, while shafts of the Aspidodiadematoida are verticillate with a lumen subdivided into dissepiments. Of all spines seen so far, only some aboral spines of Echinothurioida (e.g., Asthenosoma: Echinothuriidae; Phormosoma: Phormosomatiidae, Kamptosoma: Kamptosomatidae) show remote similarities with our material by the occurrence of oval pores, septae bearing irregularly distributed thorns, a thin cyclinder and a wide lumen. However, neither occur hoof-like spine terminations (Echinothuriidae) nor irregularly curved septae (Kamptosomatidae), why both groups are no likely source. Data on Phormosomatidae are discussed during the symposium. No Upper Cretaceous record of this spine type exists from the neighbouring Site U1407 (ca. 1,600 m palaeo-water depth), nor exist post-Cretaceous records in general. The “beast from the deep” could, therefore, represent an extinct deep-sea echinothurioid lineage, not surviving the K/Pg boundary impact event.

This study presents detailed micropaleontological analyses of the Cenomanian Turonian shallow water carbonate system of the Ajlun Group in a regionally defined sequence stratigraphic framework. Two outcrop sections were studied with a total thickness of 700m representing proximal (Bustani) to distal (Mujib) settings. Over 300 thin sections and disaggregated analyses were produced and integrated with existing sedimentological, nannopaleontological, and isotopic data. The Early/Middle Cenomanian boundary interval is marked by the highest abundance and diversity of benthic foraminifera including index fauna, Praetaberina bingistani and Nummufallotia apula in the Bustani section and Praelaveolina tenuis and Meandropsina vidali in the Mujib section. Benthic foraminiferal diversity declines significantly at the K130 sequence boundary surface that corresponds to a sealevel drop positioned around this substage boundary. It marks the change from a rimmed carbonate platform to a shallow ramp dominated by oyster shells and small planktic foraminifera interbedded with faverina and ostracods. Larger benthic foraminifera reappear briefly in Late Cenomanian prior to Oceanic Anoxic event 2, marked by the abundance of dwarf heterohelicids and buliminids coinciding with a positive carbon isotope excursion.

Following OAE2, the Turonian interval shows a recovery of planktic foraminiferal diversity followed by carbonate platform settings but with large gastropods and rare small benthic foraminifera. The Middle/Late Turonian boundary is represented in a thin interval dominated by Cuneolina pavonia parva? in peloidal grainstone facies. In addition to the age dating contribution, this study illustrates how micropaleontological information can document subtle environmental changes that refine the sequence stratigraphic model.

Larger benthic foraminifera (LBF) live mostly in warm, shallow seas where their diversity is influenced by light and the nature of the sea floor. Modern LBF are large, possess complex shells, and exhibit a life cycle that results in dimorphism or trimorphism. This reflects their relationship with photosynthetic symbionts, which supply energy and influence their depth distribution. Additionally, their limited dispersal often results in high levels of endemism. During the Cretaceous, the growth and diversification of benthic communities was promoted by a generally warm climate and the widespread presence of shallow carbonate platforms worldwide. Within these, most foraminifera identified in the literature as LBF were highly prolific during that period; however, certain biological aspects remain unknown. This poses a limitation in determining whether a fossil species can be strictly classified as an LBF, since reliable insights extending from modern to ancient taxa currently rely solely on test morphology. This review examines key Cretaceous foraminiferal species that appear to exhibit one or more characteristics of LBF. It concludes that only certain Cretaceous species qualify as true LBF when the biological criteria defined from modern forms are strictly applied. The others, lacking some of these defining features, remain in a sort of "purgatory," although the architectural complexity of their shells still offers valuable insights into biostratigraphy and evolution.