There are numerous reports of trilobites that survived macrophagous attacks and whose injuries healed. Significantly, rarely observed, however, are such repaired injuries to the head or especially to the eyes. Here, we report and interpret the healed laceration of a phacopine trilobite eye, revealing details about the genetic program that established the order of lens arrangement in a schizochroal eye. The first and superordinate level is the arrangement of the lenses in vertical and spiral-horizontal rows, which not only seems to be a forced arrangement as a result of eye growth, but which follows a genetically determined program since the order of the lenses is completely restored in one step, even after the visual surface has been destroyed completely. The size of the lenses, and thus their light-gathering capacity, is more flexible and interacts with the context within the pattern of the lenses. The origin of the lesion remains unresolved.

Graptolites of the Pleurograptus linearis Biozone have long been known to straddle the boundary between the British Caradoc and Ashgill series (C/A) of the Ordovician. This is largely based on observations of these graptolites in the Whitehouse Subgroup of the Girvan area in Scotland. However, in the type Cautleyan-Rawtheyan area of northern England, graptolites of the same biozone range into the Rawtheyan Stage of the Ashgill Series, impacting the utility of the P. linearis Biozone for regional and global correlation around the C/A boundary. Here we use chitinozoan microfossils to correlate the strata in Girvan and Cautley in an independent manner. We present new chitinozoan data from an exhaustive sampling effort across the Whitehouse Subgroup from several locations in Girvan and correlate these with other key sections that contain graptolites from the P. linearis Biozone and index chitinozoans of Baltoscandian–Avalonian and Laurentian zonal schemes. During the Late Ordovician, Girvan occupied a pivotal geographical position allowing linkages between Laurentian faunas and those of both Baltica and Avalonia. Our samples yielded some typical Laurentian chitinozoan species (e.g., Hercochitina cristata, Kalochitina multispinata), next to several well-known index species of mixed Baltoscandian–Avalonian affinity, relatable to the Fungochitina spinifera and Tanuchitina bergstroemi biozones and their subzones; the latter can be traced into key areas of Ordovician stratigraphy in England and Wales on Avalonia, and Denmark and Sweden on Baltica. These correlations suggest that the P. linearis Biozone at Girvan correlates to an interval starting in the Onnian and extending into some part of the (lower) Cautleyan Stage at Cautley, northern England. The Girvan district is confirmed as a key area to document mixed faunas from Laurentian–Avalonian–Baltic realms, and has potential as a stepping stone between rather distinct chitinozoan provinces.

Bohemilla (Bohemilla) scotica Reed, 1914 and B. (B.) xesta sp. nov. are described from the middle Katian (around the Caradoc–Ashgill boundary in terms of the regional chronostratigraphical scheme) of the Girvan district of SW Scotland. Their occurrence in the Upper Whitehouse Subgroup of the Ardmillan Group is in the youngest recorded part of the range of the genus. Their association with a diverse deep-water trilobite fauna, including members of the cyclopygid biofacies, accords well with the earlier occurrences of the genus that first appeared in the Early Ordovician. The earlier history of Bohemilla was largely at higher latitudes and its occurrence at Girvan, and probably at a broadly equivalent stratigraphical level in Ireland, marks the extension of the range of the genus to the Laurentian margin of the Iapetus Ocean in the latest part of its history.

A factor analysis of an exhaustive sample-based dataset of Cambrian (Miaolingian) to Silurian radiolarian species occurrences allows the detection of three evolutionary faunas composed of specific radiolarian families, which record simultaneous increases and decreases in radiolarian species richness over geological time. The oldest evolutionary fauna is composed of Cambrian to Early Ordovician archaeospicularians, assigned to the families Echidninidae and Palaeospiculidae, and of the entactinarian family Protoentactiniidae. This evolutionary fauna is complemented in the Early Ordovician by the oldest spumellarian family Antygoporidae, as well as by the order incertae sedis families Aspiculidae and Proventocitidae. Next, a new evolutionary fauna emerged during the Darriwilian and persisted during the Sandbian; it is dominated by the spumellarian family Inaniguttidae and to a lesser extent by the entactinarian families Haplentactiniidae, Entactiniidae and Pylentonemidae. Last, a third evolutionary fauna emerged since the Katian (Late Ordovician) and continued during the entire Silurian; it is dominated by the archaeospicularian family Secuicollactidae, the entactinarian family Paleoscenidiidae and the spumellarian family Haplotaeniatidae. These three early Palaeozoic radiolarian evolutionary faunas seem to correlate with major climatic and biotic changes known in the Ordovician: (i) the transition between the first and second evolutionary faunas is sharp and underlined by profound changes in taxonomic composition and turnover during the Middle Ordovician; it is correlated with the sudden early Darriwilian climate shift, global cooling and the main phase of the Great Ordovician Biodiversification Event (GOBE); (ii) the transition between the second and third evolutionary faunas is correlated with the Late Ordovician mass extinction (LOME; Katian–Hirnantian) and associated climate cooling.

Land snail shells are usually avoided for radiocarbon dating, due to the possible presence of dead carbon, although measurements on certain small species can be reliable. However, terrestrial gastropods, which are often abundant and well preserved in favorable sedimentary contexts, may represent an important source of material for precise dating. In this study, the shell selection method and radiocarbon results are presented, based on about twenty dates, from well-known and reliable archaeological contexts mostly from the Languedoc (southern France) and covering different cultural periods of the Holocene. Chronological controls are provided by dates based on plant remains, archaeological artifacts and stratigraphy, as well as geomorphological and environmental interpretations. The results obtained based on gastropod shells show a good agreement with the expected dates. In some examples, the target period is quite large, making it difficult to determine the degree of accuracy. However, other tests give perfectly synchronous dates between botanical or archaeological material and mollusks. Species selection takes into account that terrestrial gastropods living in the midst of vegetation are less likely to ingest fossil carbon and are therefore better suited for dating, especially wetland species, Succinella oblonga and Vertigo pygmaea. These promising results show the potential of terrestrial shells for dating archaeological sequences when prevailing biological material such as charcoal is lacking or is unreliable.

Five unknown Holocene flank eruptions from the Masaya caldera are reported here. These eruptions comprise basaltic lava flows emplaced in Masaya’s northern rift zone along the Cofradía fault zone, east of Managua City. The lava flows were defined as Mosintepe, Portillo, Gorgonia, Campuzano, and Martha units. Paleosol samples were collected below each lava flow, and radiocarbon AMS analyses were performed, yielding ages of 2250 ± 30, 1610 ± 30, 1600 ± 30, 1140 ± 30, and 790 ± 30 yrs BP, respectively. Calibrated age intervals are 285–229 cal BC for Mosintepe, 496–534 cal AD for Portillo, 496–535 cal AD for Gorgonia, 914–976 cal AD for Campuzano, and 1226–1268 cal AD for Martha; all stratigraphically consistent. These eruptions emitted magma bulk volumes between 0.02 and 0.51 km3, reaching up to 8 km from their eruptive vent and 13 km from Masaya’s polygenetic system summit crater. Their mineral paragenesis, and major and trace element geochemical fingerprint reveals a common volcanic provenance from the Masaya caldera due to lateral magma draining. This study demonstrates that basaltic lava flow flank eruptions are common in the Masaya caldera along its northern volcanic rift zone. Therefore, this information should be considered in future hazard and risk assessments.

The green tree python is quite a favorite pet for sale on the international market. The species is therefore protected by the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES). Since the illegal poaching of large numbers of specimens in the wild might lead to the detriment of native populations, and wildlife breeding farms were found to be serving as conduits to funnel wild-caught green tree pythons out of Indonesia, a forensic tool to distinguish wild-caught from captive-bred specimens could support the enforcement of CITES protections. To disrupt the illegal trade of green tree pythons, we have developed an effective tool to distinguish the animals supposedly bred in captivity from those caught in the wild, based on the strontium isotope composition in conjunction with trace element data. Like in human hair, 87Sr/86Sr values seem to vary according to the relative contribution of endogenous and exogenous sources. Thus, we infer that if there is enough sustainable strontium available for the analysis, it might be possible to use the 87Sr/86Sr values in parallel with trace elements to distinguish wild-originated specimens from the in captivity-bred ones. Indeed, our pilot study on the shed skins of animals where the geographic origin was either the Czech Republic or Indonesia, confirms that shed skins can be effectively used for further forensic Sr radiogenic isotope analyses.

Sexual dimorphism of the mineralised part (shell, carapace) of invertebrate animals is recognised in many fossil groups; for example, in ammonoids, trilobites and especially in ostracod crustaceans, arguably the most species-rich and specimen-abundant group of arthropods in the fossil record. Shell dimorphism in ostracods is most stark in several major Palaeozoic groups. Beyrichioidean ostracods are known abundantly worldwide from hundreds of genera in Ordovician to Carboniferous deposits and are characterised by a distinctive well-defined shell dimorphism in which the presumed female of the species develops a so-called brood pouch (crumina) on each valve. However, Ametrobeyrichia schizopyge, a Silurian ostracod species from the UK, challenges the definition of the group: it is, ostensibly, a non-dimorphic beyrichioidean. Reasons for its seemingly non-dimorphic nature include heterochronic mechanisms. Apparently not all beyrichioideans had cruminal brood care strategy.

With extraordinary preservation, the bivalved Cassicaris clarksoni gen. et sp. nov. from the early Cambrian (Stage 3) Xiaoshiba Lagerstätte in Kunming, China, is characterised by having an anterior cardinal spine and a heavily segmented body, including an abdomen with a heavily sclerotised shell. Anatomically, the antennulae are small and the antennae are robust with seta-bearing podomeres, possibly of predatory function, followed by the other five pairs of biramous cephalic limbs. There are about 11 pairs of thorax segments, each corresponding to a pair of biramous limbs, including a multi-segmented endopod with feather-like podomeres and terminal spines, and a small paddle-shaped exopod fringed with setae. The bulbous, stalked eyes, which exhibit fineness of vision, infer adaptation to a vagile epibenthic lifestyle. Functionally, such assorted appendages may indicate an efficient suspension-feeding strategy for capturing tiny zooplankton. The median eye is presumably not a typical ocellar system but another compound eye, which may offer further insights into the evolution of compound eyes. Cladistic analysis implies that Cassicaris is a sister taxon to Pectocaris and Jugatacaris; these intriguing euarthropods are critical for discerning their body plan and living habits. Our findings offer fresh insights into the early evolution of Cambrian euarthropods, characterised by notable morphological disparity and ecological diversity. These fossils, including not only many intact individuals but also a few with well-preserved soft parts, form well-characterised groupings, making the broad pattern of Cambrian arthropod systematics increasingly consensual.