2026 in paleomalacology

Ammonite research • Neige & van Tiel (2026) study the evolutionary history of the family Dactylioceratidae, and interpret the pattern of changes of their taxonomic and morphological diversity as consistent with background extinction, possibly linked to species specialization making them vulnerable to such extinction. • A study on the composition of the Late Jurassic (Kimmeridgian) ammonite faunas of the subtilicaelatum and desmoides biohorizons of the Lacunosamergel Formation (Germany) is published by Jantschke et al. (2026). • Aguirre-Urreta et al. (2026) report evidence of exceptional preservation of the periostracum in specimens of Bochianites neocomiensis and Lissonia riveroi from Vaca Muerta (Argentina), interpreted as indicative of highly conservative composition of the periostracum throughout the evolutionary history of conchiferan molluscs. • Frau (2026) revises the affinities of the genera Vergunniceras and Paracheloniceras, and names a new subfamily Paracheloniceratinae within the family Douvilleiceratidae. • A study on the biostratigraphy of the Barremian-Aptian ammonite fossils from the southern edge of the Vercors Urgonian platform (France) is published by Pictet, Ferry & Pietra (2026). • Kennedy & Klinger (2026) revise the species referred to the subgenus Pervinquieria (Styphloceras), reinterpreting them all as a single variable species Pervinquieria (Pervinquieria) nodosocostata. • Hefny et al. (2026) revise the composition of Cenomanian and Turonian ammonite assemblages from the strata of the Galala and Umm Omeiyid formations at Wadi Qena (Egypt). • Bensekhria et al. (2026) study the biostratigraphy of the Albian–Turonian ammonite fossils from the Aurès Basin (Algeria) and compare the composition of the studied ammonite assemblages with those from Tunisia, Western Europe and the Western Interior Seaway, reporting evidence of differences that were likely driven by climatic gradients, marine barriers and variable migration pathways. ==Other cephalopods==

Other cephalopod research • Evidence of impact of distribution of mineral deposits in chambered shells on buoyancy and maneuverability of orthocone cephalopods is presented by Peterman, Landman & Ciampaglio (2026). • Galácz (2026) interprets Bayanoteuthis rugifer as an Eocene belemnite. • A study on the early ontogenetic development of shells of members of the genus Boionautilus is published by Turek & Manda (2026), who place the studied genus in the family Lechritrochoceratidae, and transfer "Nautilus" sternbergi to the genus Cumingsoceras. • Evidence of nautiloid affinities of Pohlsepia mazonensis is provided by Clements et al. (2026), who interpret the studied species as a junior synonym of Paleocadmus pohli. • Fossils of members of the genus Cenoceras otherwise known from the Aalenian–Bajocian strata from Western Europe are described from the Bathonian strata from the Gnaszyn clay-pit (Poland) by Jain, Salamon & Bălc (2026), extending known geographical and stratigraphical range of the studied nautilids. • Patarroyo et al. (2026) describe new fossil material of Aturia peruviana from the Paleogene strata of the San Jacinto Formation (Colombia), and interpret their morphology as supporting the classification of Aturia colombiana as a junior synonym of A. peruviana. • Evidence from the study of extant nautiloid cephalopods and from the study of oxygen isotope shell thermometry of nautiloid fossils, indicating that modern nautiloids live deeper and grow in colder water than any of their extinct relatives other than members of the genus Aturia, is presented by Ward et al. (2026). • New pseudorthocerid and aulacocerid fossil material is described from the Middle Triassic (Anisian) strata of the Rifu Formation (Japan) by Niko & Ehiro (2026). • Sealey & Lucas (2026) revise the fossil record of Cretaceous ammonites and nautiloids from New Mexico (United States). • Evidence from the study of fossil material of Nanaimoteuthis jeletzkyi and "Paleocirroteuthis" haggarti (transferred to the genus Nanaimoteuthis) from the Cretaceous strata in Canada and Japan, indicating that Nanaimoteuthis was an octopus belonging to the group Cirrata and that members of this genus were some of the largest known invertebrates and among the largest known Cretaceous marine predators, is presented by Ikegami et al. (2026). ==Bivalves==

Bivalve research • Evidence of utility of the study of rudist shells from the Maastrichtian Cárdenas Formation (Mexico) in reconstruction of environmental conditions in the western Tethys Ocean during the Cretaceous is presented by Juárez-Aguilar et al. (2026). • Pérez, Mosquera & Cuitiño (2026) report the discovery of fossil material of Limopsis insolita from the Miocene Gaiman Formation (Argentina), extending its known geographic distribution northwards and representing the first unambiguous record of a member of the genus Limopsis in deeper-water settings in the region. • Knight (2026) studies the composition of two assemblages of Miocene (Tortonian) bivalves from S'Algar (Menorca, Spain), interpreted as originating from a middle ramp environment that changed through time as a result of changes in the frequency and directionality of storms and currents. • Amano, Hamuro & Hamuro (2026) describe new fossil material of Nipponocrassatella osawanoensis and "Oxyperas" osawanoensis from the Miocene strata of the Kurosedani Formation (Japan), and allocate the latter species to the genus Pseudoxyperas. • Amano (2026) describes new thyasirid and vesicomyid fossil material from the Pleistocene strata of the Umegase Formation (Japan), transfers "Thyasira" inflata Yabe & Nomura (1925) to the genus Maorithyas, and coins a replacement name Mendicula angolensis for the extant species Thyasira (Mendicula) inflata Payne & Allen (1991). • Osipova et al. (2026) revise the composition of the venerid assemblage from the Pleistocene Szekou Formation (Taiwan). • Evidence from the study of bivalves from the Pleistocene and Holocene strata from Florida (United States) and Italy, indicating that trematode infestation caused abnormal morphological development of shells of affected bivalves and that hampers species delineation and morphometric analyses of fossil bivalves, is presented by Jang et al. (2026). ==Gastropods==

Gastropod research • Evidence of a southward expansion of nerineoid gastropods from the Boreal Realm into the Tethyan Realm during the Jurassic period is presented by Leshno Afriat, Rabinovich & Edelman-Furstenberg (2026). • Li, Xiao & Yu (2026) report the discovery of new fossil material of Coptocheilus electrothauma (originally named Schistoloma electrothauma) from the Cretaceous amber from Myanmar, and revise the diagnostic traits of this species. • The first known fossils of members of extant species Lanayrella vagabunda are reported from the Miocene strata of the Monte León Formation (Argentina) by Di Luca & Pastorino (2026). • Osipova & Lin (2026) study the composition of the assemblage of pelagic gastropods from the Pleistocene strata of the Szekou Formation (Taiwan), and find no evidence of significant spatial and temporal separation of Pleistocene holoplanktonic gastropod assemblages from different parts of the Indo–West Pacific region. ==Other molluscs==

Other molluscan research • Hou et al. (2026) provide new information on the sclerite ultrastructure of Cambrian maikhanellids from the Kuanchuanpu Formation (China), and interpret maikhanellids as a distinct clade in the stem group of Mollusca. • A study on the microstructure of shells of Bemella simplex, Latouchella korobkovi and Merismoconcha tommotica from the Cambrian Bayangol Formation (Mongolia), providing evidence of occurrence of a bidirectional foliated aragonite microstructure, is published by Xia & Li (2026). ==General research==

• Evidence from the study of the molluscan fossil record, indicative of higher frequency of origination of unique and first occurrences of repeated phenotypes during the first 96 million years of the evolutionary history of the group (in the Cambrian and Ordovician) than during the remaining 444 million years of their history, is presented by Vermeij & Thomson (2026). • A study on the fossil record of bivalves and gastropods from the North American Pacific coast ranging from the Late Cretaceous to the Eocene, providing evidence of loss of morphological diversity after the Cretaceous–Paleogene extinction event and a recovery during the Paleocene, is published by Contreras-Figueroa, Hendy & Aragón (2026). • Morales-Ortega & González-Barba (2026) study the impact climate and environmental changes on composition of Eocene molluscan assemblages from North and South America, reporting evidence of faunal exchanges between the Atlantic, Pacific and Caribbean Sea, and evidence indicating that peaks of molluscan biodiversity coincided with hyperthermal events. • Bellosi et al. (2026) revise the age and distribution of the molluscan assemblages from Patagonia living at the time of the Chattian-Langhian marine incursions into southern South America, and provide calibrated dating of the youngest fauna dominated by tropical species. • A study on the fossil record of late Neogene bivalves and gastropods from the Atlantic coast of North America, providing evidence of links between basal metabolic rates and extinction patterns of the studied molluscs, is published by Rojas-Ariza, Strotz & Lieberman (2026). • Evidence from the study of the fossil record of molluscs from the East Pisco Basin on the Peruvian continental margin ranging from the late Miocene to the present, indicative of a major faunal shift between 6 and 4 million years ago, is presented by Medina-Franco et al. (2026). • DeVries (2026) studies the composition of late Pliocene and Pleistocene marine molluscan assemblages from northwestern Peru, and reports evidence of a shift from a cool-water to warm-water fauna during the Pleistocene that might have been linked to uplift of the coastal plain and/or altered equatorial circulation. • Betz et al. (2026) evaluate functional traits of Pliocene-Holocene bivalves and gastropods from the West Atlantic, finding no evidence of a significant association of the studied traits with increased extinction risk of the studied molluscs. == References ==