2023 in paleomalacology

Ammonite research • A study on the swimming capabilities of ammonites, aiming to determine hydrodynamic costs and advantages provided by different conch geometries, is published by Ritterbush & Hebdon (2023). • A study on the mechanics and fluid dynamics of ammonite swimming is published by De Blasio (2023). • Revision of the Middle Triassic ammonite assemblage from the Samobor and Žumberak Mountains (Croatia) is published by Vidaković et al. (2023), who consider "Protrachyceras" dorae Salopek (1912) to be the only unambiguously valid species with a holotype from the Gregurić Breg locality, and transfer this species to the genus Eoprotrachyceras. • Revision of the early Kimmeridgian ammonites from the planula Biohorizon of the Wohlgeschichtete Kalk Formation (Germany) is published by Jantschke & Schweigert (2023). • Revision of acanthohoplitid taxa from the Aptian strata from Dagestan (Russia) is published by Frau (2023), who considers Protacanthoplites abichi to be a synonym of Acanthohoplites aschiltaensis, and retains A. aschiltaensis as the senior valid name. • Evidence from the Albian fossil material from the Clansayes locality (France), interpreted as indicative of the presence of sexual dimorphism in Mariella bergeri, as well as indicating that upper Albian Mariella, lower Cenomanian Mariella and lower Cenomanian Hypoturrilites share the same peristome morphology, is presented by Jattiot et al. (2023). • A specimen of Prionocyclus germari found in association with an aptychus referred to the genus Praestriaptychus is described from the Turonian strata near Úpohlavy (Czech Republic) by Košťák et al. (2023). • A specimen of Mammites nodosoides, preserved with bite traces interpreted as most likely resulting from a lethal attack of a mosasaur directed at the apertural part of the ammonite with the head and arm crown, is described from the Turonian Bílá Hora Formation (Czech Republic) by Mazuch et al. (2023). • A study on the evolution of the peculiar morphology of Pravitoceras sigmoidale is published by Misaki, Okamoto & Maeda (2023). • Shigeta & Maeda (2023) describe new fossil material of ammonites from the Maastrichtian Krasnoyarka Formation (Sakhalin, Russia), including fossils of Zelandites varuna, Gaudryceras seymouriense, Pachydiscus subcompressus and Anagaudryceras mikobokense, and interpret the presence of these species as indicative of the influx of immigrant ammonite species into the Northwest Pacific region during late Maastrichtian, which might have been associated with cooling after the greenhouse Middle Maastrichtian Event. ==Other cephalopods==

Other cephalopod research • A study on the phylogenetic relationships of belemnites is published by Stevens et al. (2023). • Dzyuba et al. (2023) report the discovery of the fossil material of Arcobelus cf. krimholzi from the Jurassic (Toarcian–Aalenian) strata from the Kuoika kimberlite field (northeastern Siberian Platform, Olenek Uplift), and interpret putative Late Jurassic or Early Cretaceous belemnites from the studied area as possibly of Bajocian–Bathonian age. • Evidence from clumped and stable isotopes and trace element data for three specimens from the Valanginian of southern Tibet and Madagascar, interpreted as indicating that Acroteuthis acrei and Duvalia sp. occupied shallower and warmer waters than Hibolithes jaculoides and that the latter belemnite was a fast swimmer that undertook vertical migration in the water column, is presented by Wang et al. (2023). • Dernov (2023) reports the preservation of color patterns on conchs of nautiloid cephalopods from the Carboniferous (Moscovian) Kamenskaya Formation (Luhansk Oblast), interpreted as indicative of the presence of disruptive coloration. • Wilmsen (2023) redescribes the Coniacian nautilid "Nautilus" sinuatoplicatus and transfers it to the genus Anglonautilus, filling a gap in the fossil record of this genus which was previously unknown from the late Cenomanian to early Campanian. • A study aiming to determine the metabolic rates of ammonites and nautiloid cephalopods living at the end of the Cretaceous is published by Tajika et al. (2023), who find that the nautiloid Eutrephoceras had a lower metabolic rate than co-occurring ammonites, and argue that the lower metabolic rate in nautiloids might have been an advantage during the Cretaceous–Paleogene extinction event. • Klug et al. (2023) report evidence of preservation of axial nerve cords in specimens of Jurassic cephalopods from France and Germany. • Syllipsimopodi bideni, originally described as a member of the clade Vampyropoda, is reinterpreted as a probable junior synonym of Gordoniconus beargulchensis and unlikely to be a vampyropod by Klug et al. (2023); in a subsequent study Whalen & Landman (2023) support the interpretation of S. bideni as distinct from G. beargulchensis, but hint that further analyses might be needed to confirm the hypothesis that it is a vampyropod. • Rogov et al. (2023) report the discovery of jaws of decabrachian coleoids from the Toarcian deposits of the Vilyui River basin (Sakha, Russia), representing the first finding of coleoid jaws in the Lower Jurassic strata in Siberia reported to date. • Tanabe & Misaki (2023) describe new coleoid fossil material from the Upper Cretaceous Yezo Group (Japan), including a large upper jaw of an indeterminate member of Oegopsida and two lower jaws possibly belonging to members of the species Longibelus matsumotoi, and interpret the anatomy of the studied lower jaws as supporting the interpretation of Longibelus as a relative of Decapodiformes. • An assemblage of coleoid cephalopods, including the latest record of Belosaepia blainvillei, is described from the Eocene (Priabonian) Mandrykivka Beds (Ukraine) by Dernov & Demianov (2023). • Mironenko (2023) describes phosphatized jaws of cephalopods (mostly coleoids, but also one nautilid specimen) from the Upper Jurassic, Lower and Upper Cretaceous localities in Russia, including jaws likely belonging to large-bodied coleoids. ==Bivalves==

Bivalve research • Description of shell microstructure and muscle attachment scars from the inner surface on the shell in specimens of Fordilla troyensis from the Cambrian Aftenstjernesø Formation (Greenland) is published by Peel (2023). • A study on the fossil record of bivalves is published by Zhou et al. (2023), who report that bivalves did not undergo and increase in taxonomic, morphological and functional diversity until the Ordovician, and did not undergo a burst of functional diversity relative to taxonomic diversity even during their Ordovician diversification. • A study on the diversification dynamics of bivalves and brachiopods throughout their evolutionary histories is published by Guo et al. (2023), who interpret their findings as indicating that the switch from brachiopods to bivalves as major seabed organisms was unlikely to be caused by competitive exclusion of brachiopods by bivalves, but rather was likely caused by loss of brachiopod diversity in the Permian–Triassic extinction event and by bivalve diversification in the Cretaceous and Cenozoic that wasn't matched by brachiopods. • A study on changes of taxonomic and functional diversity of bivalves during the Triassic-Jurassic transition is published by Abdelhady et al. (2023), who consider the sea-level fall causing the destruction of shallower marine habitats to be the primary cause of bivalve extinction in the studied time interval. • Description of a new Cenomanian rudist assemblage from the Gattar Member of the Zebbag Formation (Tunisia), and study on the relationships between the new assemblage and other Cenomanian rudist assemblages from North Africa and the Levant region, is published by Philip, Negra & Bachari (2023). • Özer & Săsăran (2023) reexamine the holotype and paratypes of Lattenbergites hermi, and interpret it as a junior synonym of the radiolitid species Joufia milovanovici. • Evidence from fossils from the Pecínov Member of the Peruc–Korycany Formation and from the Bílá Hora Formation (Czech Republic), indicative of changes of the composition of the bivalve assemblages resulting from the Cenomanian-Turonian boundary event, is presented by Kunstmüllerová & Košťák (2023). ==Gastropods==

Gastropod research • Review of the world-wide fossil record and evolutionary history of freshwater gastropods is published by Neubauer (2023). • A study on the biogeographic distributions of pleurotomariids throughout their evolutionary history from Maastrichtian to Holocene is published by Bose, Das & Mondal (2023). • A study on the diversity of potamidids and batillariids in the Paratethys through time is published by Harzhauser et al. (2023), who interpret the studied groups as a whole not to be mangrove indicators, and find only members of the genera Mesohalina, Ptychopotamides, Terebralia and probably Tiarapirenella to be associated with mangroves during the Oligocene to early Middle Miocene in the Central Paratethys, while other members of the studied groups adapted to environments devoid of mangroves. • Revision and study on the affinities of the Plio-Pleistocene turritellids from the Atlantic Coastal Plain and Florida is published by Friend et al. (2023). ==Other molluscs==

Other mollusc research • Qiang et al. (2023) describe new fossil material of Anabarella plana from the Cambrian Yanjiahe Formation (China), and consider A. plana to be the only member of the genus Anabarella definitely present in South China. ==General research==

• Slater (2023) describes microscopic molluscan radulae from the Cambrian (Wuliuan) Borgholm Formation (Sweden), similar to the radulae of extant gastropods specialized for piercing and sucking the tissues of green algae, and interpret this finding as indicating that this form of herbivory was already present among Cambrian molluscs. • Fossil material representing the first evidence of gastropod drilling predation on molluscan prey from Coniacian is reported from the Anaipadi Member of the Garudamangalam Formation (India) by Mukhopadhyay et al. (2023). • A diverse molluscan assemblage dominated by turritellid gastropods from Kachchh (India), originally interpreted as Late Jurassic in age, is reinterpreted as more likely Miocene in age by Fürsich et al. (2023). == References ==