We describe the modes of occurrence of a vesicomyid-dominated fossil assemblage in the lowermost Pleistocene Urago Formation, a forearc basin fill on the Miura Peninsula, Pacific side of central Japan. The assemblage consists mostly of Calyptogena (Archivesica) kawamurai (Kuroda) with a minor amount of Conchocele bisecta (Conrad). The shells occur in cross-bedded and massive sandstones of an outcrop that is approximately 25 m wide and 10 m high. The sandstones are interpreted to have been formed by migration of dunes under northward- to eastward-directed bottom currents, judging from the dips of their foreset laminae. Many of the shells are disarticulated and show evidence of reworking by bottom currents, as indicated by their convex-up positions with their commissure planes dipping southwestward (up-current direction) or concordant with the cross laminae. In the massive sandstones, some articulated vesicomyids are preserved in their life position, that is, perpendicular to the bedding plane with their anterior parts oriented downward. Massive authigenic carbonates, which are developed in nearly all horizons of the vesicomyid-bearing sandstones, consist exclusively of Ca-rich dolomites (δ¹³C, -37.78‰ to -24.16‰ VPDB; δ¹⁸0, 0.69‰ to 4.35‰ VPDB). Biogenic carbonates have entirely dissolved, and some of the resulting molds are filled with dolomite-cemented fine clastics.

We consider this fossil assemblage to be an in situ cold-seep dependent assemblage because of its association with ¹³C-depleted authigenic carbonates, which clearly reflect the influence of the anaerobic oxidation of methane. We infer that the vesicomyids lived on sand dunes during time intervals between intermittent sanddeposition events under the unidirectional bottom currents.

Belemnites were a highly successful group of Mesozoic cephalopods. Their early evolutionary history is, however, still poorly understood. Previously it has been suggested that the Order Belemnitida originated in the earliest Jurassic (Hettangian) with small forms in Europe, and their occurrence was restricted to Europe until the Pliensbachian. Here we report a large specimen of the Suborder Belemnitina from the upper Pliensbachian of the Kuruma Group in Central Japan. This is the first reliable record of Pliensbachian belemnites from outside Europe and the Mediterranean area. The specimen from Japan differs from those of the coeval European genera by its large rostrum. The rostrum diameter of this specimen rather resembles that of the Middle Jurassic belemnite genus Megateuthis, the largest belemnite ever observed. This new finding provides additional evidence of the existence of belemnites with extremely large rostra in the Early Jurassic of the western paleo-Pacific area, thereby shedding new light on the early evolutionary history of belemnites.

Adocus sengokuensis sp. nov. is described on the basis of disarticulated shell elements (nuchal, first peripherals, left fourth peripheral, left second costal, left hyoplastron, and right hypoplastron) collected from a lacustrine mudstone of the Lower Cretaceous Sengoku Formation, Kanmon Group in Miyawaka City, Fukuoka Prefecture, Japan. A. sengokuensis is characterized by its small size with a carapace estimated at only 29 cm long, a trapezoidal cervical scale greater in width than length, and a narrow lateral projection of the first pleural scale of the fourth peripheral. Small size and wide cervical scale suggest that this new species is the most basal taxon of the genus Adocus.

This study describes a brachiopod fauna, consisting of 15 species in 15 genera, from the lower part of the Takakurayama Formation at the locality T₁ in the Takakurayama area, Abukuma Mountains, South Kitakami Belt, northeastern Japan. The fauna is considered to be late Permian (Wuchiapingian) in age based on the occurrence of Haydenella wenganensis, Costatumulus tazawai and Pterospirifer alatus. In terms of palaeobiogeography, the Takakurayama (T₁) fauna is a mixed Boreal—Tethyan fauna with Chonetinella, Lamnimargus, Megousia, Costalumulus, Yakovlevia, Neospirifer, Gypospirifer, Alispiriferella and Pterospirifer as the Boreal (anti-tropical) elements, and Haydenella, Transennatia and Echinauris as the Tethyan (tropical) elements. The fauna is allied with the middle—late Permian brachiopod fauna of South Primorye, Far Eastern Russia.

An early Chesterian (early Carboniferous; Late Mississippian) nautiloid fauna is described from the Ruddell Shale Member of the Moorefield Formation in Arkansas, Midcontinent North America. It consists of the three orthocerids, Euloxoceras buffalowallowense sp. nov., Mitorthoceras perfilosum Gordon and Moorefieldoceras yochelsoni gen. et sp. nov., and the two nautilids, Tylonautilus sp. and Peripetoceras milleri sp. nov. Reexamination of M. perfilosum, the type species of the genus, provides grounds for emendation of the generic concept emphasizing the supracentral position of the siphuncle. Moorefieldoceras is differentiated from comparable genera by its relatively rapid shell expansion, prominent annulations with a distinct ventral sinus, and relatively large siphuncle diameter with a central to subcentral position.

Eophyton toolmarks from the early Cambrian Mickwitzia Sandstone of Sweden were examined to assess the characteristics of the Eophyton producer. Based on these observations, the producer is inferred to be an organism carrying a large, neutrally buoyant frond-like structure or crown of tentacles that acted as a sail in water currents. Attached to this sail, possibly via a stalk, was a smaller structure with a diameter ranging between 3 and at least 100 mm, weighted with sediment contained in its interior and/or adhering to its exterior. This weighted anchor plowed the Eophyton furrow while the organism was dragged by water currents, probably in connection with storm events. The anchor was roughly discoidal in shape, with a perimeter that carried small tubercle-like projections and a few deep folds, and was sufficiently flexible to sag against the bottom under its own weight. Psammocorals have been proposed in the literature as possible Eophyton producers. Among the psammocorals from the Mickwitzia Sandstone, Protolyellia can be dismissed as an Eophyton producer, while Spatangopsis cannot be firmly excluded but does not fulfill all morphological requirements. Remaining possibilities are an, as yet, unknown psammocoral with a non-cemented sand skeleton, an actinian-like cnidarian, a seaweed or a kelp-like alga.