2023 in arthropod paleontology
2023 in arthropod paleontology is a list of new arthropod fossil taxa, including arachnids, crustaceans, trilobites, and other arthropods (except insects, which have their own list) that were announced or described, as well as other significant arthropod paleontological discoveries and events which occurred in 2023. Chelicerates

Arachnids

Arachnid research
 New specimens of Compluriscutula vetulum, providing new information on the morphology of this tick, are described from the Cretaceous amber from Myanmar by Chitimia-Dobler et al. (2023). A trigonotarbid arachnid specimen is described from the Carboniferous (Moscovian) Almazna Formation (Donetsk Oblast) by Dunlop & Dernov (2023), extending known distribution of trigonotarbids in Europe. A study on the anatomy and affinities of Geralinura brittanica and Proschizomus petrunkevitchi is published by Garwood & Dunlop (2023), who reinterpret P. petrunkevitchi as a whip scorpion rather than a stem-schizomid. Probable new specimen of Mesoproctus rowlandi, representing the first fossil whip scorpion specimen preserved with book lungs, is described from the Lower Cretaceous Crato Formation (Brazil) by Alberto et al. (2023). The first known male specimen of Strotarchus paradoxus is described from the Miocene Mexican amber by García-Villafuerte & Ibarra-Núñez (2023). A study on the phylogenetic relationships of extant and fossil members of Palpimanoidea is published by Wood & Wunderlich (2023), who interpret their findings as indicative of closer relationships of palpimanoids from the Cretaceous amber from Myanmar with the Gondwanan taxa, and indicative of dispersal of Gondwanan lineages through the Burma Terrane into the Holarctic in the Cretaceous. Richardson, McCurry & Frese (2023) describe fossil material of a member of the genus Simaetha from the Miocene of Australia, interpreted as consistent with the molecular-based studies indicating that the radiation of the astioid jumping spiders at the Oligocene/Miocene transition happened in Australasia. Eurypterids

Eurypterid research

Xiphosurans

Xiphosuran research
 A study on the evolution of the developmental patterns of xiphosurans is published by Lustri et al. (2023), who find evidence of changes in the allometric growth of xiphosurans related to adaptations to different environments, but also report that the studied changes were relatively minor compared to the diversity of patterns of allometric growth observed in eurypterids and chasmataspidids. Klompmaker et al. (2023) describe a specimen of Limulitella bronnii from the Anisian Muschelkalk sediments of the Vossenveld Formation (Netherlands), extending known temporal range of this species, and provide the diagnosis of L. bronnii for the first time. Other chelicerates

 Siveter et al. (2023) describe two new specimens of Haliestes dasos from the Silurian Coalbrookdale Formation (United Kingdom), interpret their anatomy as indicative of adaptation of the studied species to a different mode of feeding than in living sea spiders, as well as possibly indicative of the presence of sexual dimorphism, and assign H. dasos to the stem group rather than the crown group of Pycnogonida. Revision of the Callovian sea spider taxa from the La Voulte-sur-Rhône (France) is published by Sabroux et al. (2023), who assign the studied fossil to Pantopoda, crown-group Pycnogonida, assign Palaeopycnogonides gracilis to the new family Palaeopycnogonididae, and interpret Colossopantopodus boissinensis and Palaeoendeis elmii as members of the families Colossendeidae and Endeidae, respectively. General chelicerate research

Crustaceans

Malacostracans

Malacostracan research
 Chény, Charbonnier & Audo (2023) reexamine the fossil record of lobsters from the Middle Jurassic of Normandy (France), providing evidence of the presence of sexual dimorphism in Glyphea dressieri and proposing the first reconstruction of this lobster. Putative hypothalassiid Lathahypossia aculeata is reinterpreted as a xanthid by Ossó & Ng (2023). A specimen of Araripenaeus timidus with a swelling on its carapace which might be indicative of infestation by bopyrid isopods is described from the Lower Cretaceous Romualdo Formation (Brazil) by Lima et al. (2023), representing the oldest evidence of parasitism in marine dendrobranchiate shrimps reported to date. A study on the extinction and survival of the decapod crustacean groups during the Cretaceous–Paleogene extinction event is published by Schweitzer & Feldmann (2023). Ostracods

Ostracod research

Thecostracans

Thecostracan research

Other crustaceans

General crustacean research

Insects

Megacheirians

Megacheirian research

Radiodonts

Radiodont research
 A study on molting patterns and ontogeny in Stanleycaris is published by Moysiuk & Caron (2023), who find evidence for two distinct fossil types of Stanleycaris (carcasses and molted exoskeletal remains), interpret their findings as confirming that radiodonts grew by periodic ecdysis, and consider the general pattern of molting in Stanleycaris to be likely shared with other radiodonts and possibly with other early arthropods. A study on the functional capabilities and hydrodynamic performance of the frontal appendages of Anomalocaris canadensis is published by Bicknell et al. (2023), who interpret their findings as indicating that A. canadensis targeted soft-bodied prey. Trilobites

Trilobite research
 A study on the timing of the appearance of trilobite planktic larvae is published Laibl, Saleh & Pérez-Peris (2023), who interpret their findings as indicating that Cambrian ecosystems were dominated by trilobites with exclusively benthic early post-embryonic stages, and that a progressive increase in the number of trilobite taxa that incorporated planktic stages in their development happened between the Miaolingian and the Middle Ordovician. A study on the disparity of trilobite cephalic structures across Cambrian Series 2, providing evidence that the development of disparity of various cephalic structures was constrained in different ways, is published by Holmes (2023). A study on the morphology and evolutionary relationships of Duyunaspis duyunensis, D. jianheensis and Balangia balangensis from the Cambrian Balang and Tsinghsutung formations (China) is published by Chen et al. (2023), who report evidence of gradual evolution indicative that Balangia was more likely to be an ancestor of Duyunaspis rather than its descendant. Taxonomic revision of the species belonging to the genus Abadiella is published by Wang, Peng & Zhang (2023), who consider Parabadiella, Guangyuanaspis and Parabadiella (Danangouia) to be junior junior synonyms of Abadiella, and consider the species A. huoi and A. bourgini to have wide geographic distribution in Gondwana, making stratigraphical correlations between various Gondwana regions based on Cambrian trilobites possible. A study on the morphology, ontogeny and systematics of Walcottaspis vanhornei is published by Srivastava & Hughes (2023). Hou, Hughes & Hopkins (2023) report the presence of setae on the walking legs of the Cambrian Olenoides serratus and on the gill shaft of the Ordovician Triarthrus eatoni, and interpret these setae as likely used to groom the gills of the trilobites. Evidence of the presence of countercurrent gaseous exchange mechanism in the gills of Triarthrus eatoni is presented by Hou et al. (2023). A study on the taphonomy of the Ordovician trilobites from the Walcott–Rust quarry (New York, United States) is published by Losso, Thines & Ortega-Hernández (2023), who report evidence indicating that fine-grained sediment supported the preservation of delicate appendages and facilitated their fossilization. Laibl et al. (2023) describe early developmental stages of at least nine trilobite species from the Fezouata Formation (Morocco), providing new information on the development of early Ordovician trilobites. Schoenemann & Clarkson (2023) describe specimens of Aulacopleura koninckii and Cyclopyge sibilla preserved with structures interpreted as likely median eyes, and interpret this finding as indicating that early developmental stages of trilobites possessed median eyes (probably unlike adult specimens). A study on the impact of changes of body shape and construction of Aulacopleura koninckii during its growth on changes of the style of its enrolment is published by Esteve & Hughes (2023), who find that the change in enrolment style happening at the onset of mature growth made it possible for A. koninckii to assume defensive posture regardless of the variation in the number of mature trunk segments of specimens belonging to the studied species. A study on the hydrodynamics of Microparia speciosa, indicating that it had a high stability in the water column when it was enrolled, is published by Esteve & López-Pachón (2023). Kraft et al. (2023) describe a specimen of Bohemolichas incola from the Darriwilian Šárka Formation (Czech Republic) preserved with fossilized gut contents, providing evidence of adaptation of the studied trilobite to feeding on organic remains including shells, and probably of digestive enzymes similar to those in modern crustaceans or chelicerates. Gishlick & Fortey (2023) describe a specimen of Walliserops trifurcatus with a malformed cephalic trident showing four rather than three tines, and consider its anatomy to be consistent with the interpretation of the trident as a weapon used for intraspecific combat. Fossil evidence confirming the survival of encrinurid trilobites into the earliest Devonian is reported from the Wutubulake and Mangeer formations (China) by Ma et al. (2023). A study on the impact of the Late Devonian extinctions on the taxonomic and morphological diversity of trilobites, and on the trilobite recovery after the extinction events, is published by Bault (2023). A study on the locomotion of trilobites, based on data from three-dimensional models, is published by Esteve & Rubio (2023), who find evidence for two main gait types reflecting burrowing and walking, as well as evidence indicating that the body structure constrained speed and lifestyles of trilobites. A study on changes of the morphological diversity of phacopid trilobites throughout their evolutionary history is published by Bault et al. (2023). Other arthropods

 New information on the anatomy of Kylinxia zhangi, indicating that its head was composed of six segments (as in extant mandibulates), is presented by O'Flynn et al. (2023), who interpret their findings as indicating that a six-segmented head was already present in the last common ancestor of Kylinxia and the euarthropod crown group. Redescription of Isoxys curvirostratus, incorporating data from new fossil material from the Cambrian Chiungchussu Formation (China) and focusing on the biramous appendages of this arthropod, is published by Zhang et al. (2023), who report that the appendage differentiation in Isoxys was higher than previously considered, that the trunk of I. curvirostratus was not arthrodized, and that Isoxys was one of the earliest branching members of Deuteropoda. A study on the ontogeny of Isoxys minor, based on data from specimens from the Cambrian Shuijingtuo formation (China), is published by Ma et al. (2023), who interpret the studied fossil material as indicative of only slight morphological differences between the specimens of I. minor which might have been caused by different environment, indicative of  the presence of brood care in I. minor, and well as indicative of reproductive ability at the early life stages of this arthropod. Pates & Zamora (2023) report the discovery of arthropod carapaces representing at least two taxa (including a tuzoiid) from the Cambrian (Drumian) Murero Formation (Spain), and interpret this finding as possibly indicating that Cambrian bivalved euarthropods living at higher latitudes were larger than those from low latitudes. Drage, Legg & Daley (2023) describe exuviae from a marrellid marrellomorph from the Ordovician Fezouata Formation (Morocco), providing evidence of moulting behaviour distinct from that described for Marrella splendens. A study on the morphology of early developmental stages of marrellids from the Fezouata Formation is published by Laibl et al. (2023), who report that adults and immature individuals shares the same general appendage differentiation, and avoided direct competition for food resources only by feeding on particles of different size. New information on the anatomy of Concavicaris woodfordi, including the structure of the shield, the circulatory, digestive and reproductive systems, and the appendages, is presented by Laville et al. (2023). Wellman et al. (2023) present data supporting a Silurian (late Wenlock) age of the "Lower Old Red Sandstone" deposits of the Midland Valley (Scotland, United Kingdom) preserving the fossil material of Pneumodesmus newmani, supporting the interpretation of this myriapod as the oldest known air-breathing land animal. New information on the morphology of the Carboniferous millipedes Amynilyspes fatimae and Blanziulus parriati from the Montceau-les-Mines Lagerstätte (France) is presented by Lheritier et al. (2023). General research
 New, diverse fossil material of radiodonts (including indeterminate hurdiids) and euarthropods (including Thelxiope cf. T. palaeothalassia, Perspicaris? dilatus, Branchiocaris pretiosa, Tuzoia retifera, T. guntheri, Dioxycaris argenta, bradoriids and a possible indeterminate species of Naraoia) is described from the Cambrian (Wuliuan) Spence Shale (Idaho and Utah, United States) by Kimmig et al. (2023). Naimark, Sizov & Khubanov (2023) report the discovery of a new assemblage of Cambrian arthropods from the Kimiltei site (Irkutsk Oblast, Russia), including the first records of members of Euthycarcinoidea and Synziphosurina from the Siberian platform and the first Cambrian record of Chasmataspidida from this platform. Braddy (2023) describes a resting trace of a phyllocarid crustacean from the Miaolingian Hickory Sandstone Member of the Riley Formation (Texas, United States), names a new ichnotaxon Minterichnus shieldi, and reinterprets the arthropod body fossil associated with the resting trace as a phyllocarid rather than the oldest known chasmataspidid. References 

2023 in paleontology