New trilobite taxa Trilobite research • Evidence indicating that a mechanism similar to the molecular activator/inhibitor mechanism present in vertebrates and known as the inhibitory cascade had controls on segment size development in trilobites is presented by Nikolic, Hopkins & Evans (2023). • 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. • A study on the morphology of the ventral part of the exoskeletons of trilobites from the Walcott–Rust quarry, providing evidence of adaptations facilitating complete enrolment
convergent with those present in extant arthropods, is published by Losso
et al. (2023). • 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). • Park (2023) examined trilobite specimens and shown that
hypostome is fusion of anterior sclerite and labrum. == Other arthropods ==