The Himalaya is characterized by the presence of both pre-Himalayan Palaeozoic and syn-Himalayan Cenozoic granitic bodies, which can help unravel the pre- to syn-collisional geodynamics of this orogen. In the Bhagirathi Valley of Western Himalaya, such granites and the Tethyan Himalayan Sequence (THS) hosting them are bound to the south by the top-to-the-N extensional Jhala Normal Fault (JNF) and low-grade metapelite of the THS to its north. The THS is intruded by a set of leucocratic dykes concordant to the JNF. Zircon U–Pb laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) geochronology of the THS and one leucocratic dyke reveals that the two rocks have a strikingly similar age distribution, with a common and most prominent age peak at ~1000 Ma. To the north of the THS lies Bhaironghati Granite, a Palaeozoic two-mica granite, which shows a crystallization age of 512.28 ± 1.58 Ma. Our geochemical analysis indicates that it is a product of pre-Himalayan Palaeozoic magmatism owing to extensional tectonics in a back-arc or rift setting following the assembly of Gondwana (500–530 Ma). The Cenozoic Gangotri Leucogranite lies to the north of Bhaironghati Granite, and U–Pb dating of zircon from this leucogranite gives a crystallization age of 21.73 ± 0.11 Ma. Our geochemical studies suggest that the Gangotri Leucogranite is a product of muscovite-dehydration melting of the lower crust owing to flexural bending in relation to steepening of the subducted Indian plate. The leucocratic dykes are highly refracted parts of the Gangotri Leucogranite that migrated and emplaced along extensional fault zones related to the JNF and scavenged zircon from the host THS during crystallization.

We present the first comprehensive detrital zircon U–Pb age dataset from Palaeozoic sandstones of Saudi Arabia, which provides new insights into the erosion history of the East African Orogen and sediment recycling in northern Gondwana. Five main age populations are present in varying amounts in the zircon age spectra, with age peaks at 625 Ma, 775 Ma, 980 Ma, 1840 Ma and 2480 Ma. Mainly igneous rocks of the Arabian–Nubian Shield are suggested to be the most prominent sources for the Ediacaran to middle Tonian zircon grains. Palaeoproterozoic and Archaean grains may be xenocrystic zircons or they have been recycled from older terrigenous sediment. A primary derivation from Palaeoproterozoic and Archaean basement is also possible, as rocks of such age occur in the vicinity. Approximately 4 % of the detrital zircons show Palaeozoic (340–541 Ma) ages. These grains are likely derived from Palaeozoic post-orogenic and anorogenic igneous rocks of NE Africa and Arabia. A few single grains gave up to Eoarchaean (3.6–4.0 Ga) ages, which are the oldest zircons yet described from Arabia and its vicinity. Their origin, however, is yet unknown. Detrital zircons with U–Pb ages of 1.0 Ga are present in varying amounts in all of the samples and are a feature of terrigenous sediment belonging to the Gondwana super-fan system with an East African – Arabian zircon province.

Understanding variations in body size is essential for deciphering the response of an organism to its surrounding environmental conditions and its ecological adaptations. In modern environments, large marine animals are mostly found in cold waters. However, numerous parameters can influence body-size variations other than temperatures, such as oxygenation, nutrient availability, predation or physical disturbances by storms. Here, we investigate trilobite size variations in the Lower Ordovician Fezouata Shale deposited in a cold-water environment. Trilobite assemblages dominated by small- to normal-sized specimens that are a few centimetres in length are found in proximal and intermediate settings, while those comprising larger taxa more than 20 cm in length are found in the most distal environment of the Fezouata Shale. Drill core material from distal settings shows that sedimentary rocks hosting large trilobites preserved in situ are extensively bioturbated with a high diversity of trace fossils, indicating that oxygen and nutrients were available in this environment. In intermediate and shallow settings, bioturbation is less extensive and shallower in depth. The rarity of storm events (minimal physical disturbance) and the lack of predators in deep environments in comparison to shallower settings would also have helped trilobites attain larger body sizes. This highly resolved spatial study investigating the effects of numerous biotic and abiotic parameters on body size has wider implications for the understanding of size fluctuations over geological time.

The Early Palaeozoic geology of the South China Craton (SCC) is characterized by an Early Palaeozoic intracontinental orogen with folded pre-Devonian strata and migmatites, MP/MT metamorphic rocks and Silurian post-orogenic peraluminous magmatic rocks in both the Yangtze and the Cathaysia blocks. In this contribution, we present new zircon U–Pb ages and Hf isotope data for detrital zircons from the Neoproterozoic to Silurian sedimentary sequences in the southeastern Yangtze Block. Samples from Neoproterozoic rocks generally display a major peak at 900–560 Ma, whereas samples from Lower Palaeozoic rocks are characterized by several broader peaks within the age ranges 600–410 Ma, 1100–780 Ma, 1.6–1.2 Ga and 2.8–2.5 Ga. Provenance analysis indicates that the 900–630 Ma detritus in Cryogenian to Ediacaran samples was derived from the Late Neoproterozoic igneous rocks in South China that acted as an internal source. The occurrence of 620–560 Ma detritus indicates the SE Yangtze was associated with Late Neoproterozoic arc volcanism along the north margin of East Gondwana. The change of provenance resulted in the deposition of 550–520 Ma and 1.1–0.9 Ga detrital zircons in the Cambrian–Ordovician sedimentary rocks. The εHf(t) values of these detrital zircons are similar to those of zircons from NW Australia–Antarctica and South India. This change of provenance in the Cambrian can be attributed to the intracontinental subduction between South China and South Qiangtang, and the convergence of India and Australia when East Gondwana finally amalgamated.

Mixed-layer illite-smectite from Lower Palaeozoic sedimentary rocks, on both sides of the Teisseyre–Tornquist tectonic zone (TTZ) in northern Poland, was studied by X-ray diffraction and dated by K-Ar means.

The percentage of smectite layers in illite-smectite (%S) indicates maximum palaeotemperatures of 125–135°C at the surface of Lower Palaeozoic rocks on the craton (NE of TTZ), and 110 to ≤180°C in different tectonic blocks to the SW of TTZ (area of Caledonian consolidation). The vertical changes in the %S indicate that the maximum palaeotemperatures were reached before Permian time on the craton, and before Jurassic, Triassic, Permian or Carboniferous periods but after the beginning of Devonian time in the Caledonian zone. The K—Ar ages of bentonites indicate that the maximum palaeotemperatures were reached by 370—390 Ma or even slightly earlier (Middle—late Devonian). A maximum of 3—6 km of Silurian–Devonian cover on the craton and in the TTZ is suggested by the data.

Rocks above and below the Precambrian-Palaeozoic unconformity at the base of many Palaeozoic sedimentary basins of mid-continental North America are distinguished by secondary K-feldspar, chlorite and illite. Thrusting of the Appalachian foreland is generally considered responsible for the fluid migrations which caused this alteration. We have examined secondary chlorite and illite from Cambro-Ordovician rocks which overlie the unconformity in southern Ontario, Canada. This area is situated along the interface between the Michigan and Appalachian basins. Water involved in chloritic alteration at ~150°C has an O isotope composition compatible with a basinal brine evolved from seawater. Brine migration was probably triggered by the Taconic Orogeny to the east. In comparison, the secondary illite (365–321 Ma) largely postdates the Acadian Orogeny, and the illite-forming fluids have stable isotopic compositions typical of tepid (~40–55°C) meteoric water. We suggest that basement arches beneath southern Ontario were reactivated by this orogeny, which facilitated introduction of meteoric water. Similar alteration in underlying Precambrian rocks shows that fluid flow was focused along the unconformity during the regional Ordovician brine migration, as well as during the localized Mississippian introduction of fresh water.

The early actinopterygian Mesopoma planti is reassigned to a new genus on the basis of data obtained from high-resolution computed tomography (CT) scans of an unusually well-preserved specimen from the Early Pennsylvanian of Lancashire, UK. The former M. planti is joined by two further Mesopoma species from the Late Mississippian of Scotland. CT scans of the key planti specimen bring to light new details of the dermal skull, pectoral girdle and fin. Among the cranial features, CT data reveal a specialised, anteriorly projecting preopercular bone, the location of the spiracular duct opening, presence of a so-called coronoid process on the lower jaw and the full three-dimensional shape of the snout. Of the pectoral girdle and fin, for the first time in a Palaeozoic actinopterygian it has been possible to complete a three-dimensional reconstruction of the entire endoskeleton in articulation. The fin presents new diversity within a conservative general pattern, revealing for the first time a double propterygium. Girdle shape shows that the fin orientation is derived: rotated with the leading edge dorsalmost. These details are used to identify unexploited character states for use in phylogenetic analyses, while functional implications of the fin and girdle suggest advanced locomotory control emerging among different groups of post-Devonian ray-finned fishes.

Archaeopterid trees were the main components of most Late Devonian forests. Their aerial axes characterised by a eustele with mesarch primary xylem strands, leaf traces departing radially from cauline bundles and secondary xylem tracheids with radial pits arranged in groups, are referred to the genus Callixylon Zalessky. The nineteen species of Callixylon described to date from North America, North Africa, Europe, Xinjiang and several parts of Russia range from the late Givetian to the Mississippian. In this paper, we describe a new species of Callixylon from two specimens collected in the Famennian locality of Mader el Mrakib in eastern Anti-Atlas. Callixylon wendtii sp. nov. is characterised by the presence of sclerotic nests in the pith, a new character for the genus. Its wood shows narrow rays of variable height, with unevenly distributed ray tracheids. Small vascular traces crossing the wood within the two innermost growth rings are interpreted as evidence for short-lived leaves. This discovery adds to the diversity of the genus Callixylon in an area of northern Gondwana that may have been favourable to the establishment of a diverse community of archaeopterid trees.

Tristychius arcuatus, from the late Viséan of Scotland, is known from numerous ironstone nodule-encased specimens. These are reinvestigated using computerised tomography (CT) scanning and 3-D digital reconstruction methods. CT scans of the neurocranium (braincase) corroborate many features of the existing reconstruction, but also reveal new details of the gross proportions, the external morphology and, for the first time, features of the internal morphology, including the otic skeletal labyrinth. The unusual position of the articulation for the palatoquadrate on the ventral surface of the postorbital process is confirmed, but the area for the hyoid articulation is relocated posteriorly and the configuration of nerve foramina within the orbit is changed. A preliminary phylogenetic hypothesis is offered, suggesting a place for Tristychius within a sequence of early branching events in the elasmobranch lineage. In this, Tristychius is not resolved as a hybodontid, but is instead a stem elasmobranch possibly related to genera such as Acronemus, and exemplifying anatomical conditions close to the base of the Euselachii. As such, the neurocranium of Tristychius offers important insight into a defining feature of these early members of the anatomically advanced elasmobranchs: the origin of specialised phonoreception.

To date, igneous rocks, either intrusive or extrusive, have been encountered in the Palaeozoic-Mesozoic sedimentary series of the Netherlands in some 65 exploration and production wells. Following 17 new isotopic K/Ar age determinations of the recovered rock material (amounting to a total of 28 isotopic ages from 21 different wells), analysis of the stratigraphic distribution of the penetrated igneous rock bodies showed that the timing of their emplacement was importantly controlled by orogenic phases involving intra-plate wrench and rift tectonics. Magmatism coincided with the Acadian (Late Devonian), Sudetian (early Late Carboniferous), Saalian (Early Permian), Early Kimmerian (late Late Triassic), Mid-Kimmerian (Late Jurassic), Late Kimmerian (earliest Cretaceous) and Austrian (latest Early Cretaceous) tectonic phases. This synchroneity presumably reflects (broadly) coeval structural reorganizations of respectively the Baltica/Fennoscandinavia-Laurentia/Greenland, Laurussia-Gondwana, African-Eurasia and Greenland/Rockall-Eurasia plate assemblies. Through their concomitant changes of the intra-plate tectonic stress regime, inter-plate motions induced intra-plate tectonism and magmatism. These plate-tectonics related events determined the tectonomagmatic history of the Dutch realm by inducing the formation of localized centres, as well as isolated spot occurrences, of igneous activity. Some of these centres were active at (about) the same time. At a number of centres igneous activity re-occurred after a long period of time.

The Carboniferous-Triassic Trinity Peninsula Group is a metasedimentary sequence that crops out widely in the northern Antarctic Peninsula. These are some of the most extensive outcrops in the area and hold the key to evaluating the connections of the Antarctic Peninsula in Gondwana; however, they are still poorly understood. Here we present our provenance study of the Trinity Peninsula Group using petrographic and geochemical approaches in combination with cathodoluminescence of detrital quartz in order to constrain its source characteristics and tectonic setting. Using differences in modal composition and quartz cathodoluminescence characteristics, we define three petrofacies derived from the progressive uplift and erosion of a volcano-plutonic continental arc, which exposed the plutonic-metamorphic roots. As indicated by major and trace elements, the source is felsic with a composition ranging from tonalitic to granodioritic. The relatively unweathered condition of the source area points to a dry and cold climate at the time of deposition, but this does not necessarily mean that it was glaciated. Deposition of the sediments occurred within an active continental margin, relatively close to the source area, probably along the south Patagonia–Antarctic Peninsula sector of Gondwana. Strong chronological, petrological and chemical similarities with the sediments of the Duque the York Complex in Patagonia suggest that they were derived from the same source.

Burlingia balangensis sp. nov. from the lower Cambrian of South China represents the earliest species of this genus, and suggests that the genus may have originated in South China. A revision of the genus shows that B. primitiva and B. obscura can be used in order to indentify the base of the Cambrian Stage 5 when other trilobites are absent because their last appearance datum (LAD) coincides with the first appearance datum (FAD) of Oryctocephalus indicus. Available palaeogeographic and palaeoclimatic models suggest five major palaeocurrents during Cambrian times which could control the migration patterns of the Burlingia clade from South China to Baltica.

Chondrenchelys problematica, from the Viséan (Holkerian) of Scotland, is the earliest holocephalan known from extensive cranial and postcranial material. Here, we provide a comprehensive new description of this taxon using three new specimens, in which we observe many morphological features for the first time. Much of the cranial morphology is closer to that of living chimaeroid holocephalans than was previously appreciated. For this reason, we provide original figures illustrating the chondrocranium of a hatchling Callorhinchus milii demonstrating these similarities. In Chondrenchelys, although the jaw articulation is positioned at the posterior margin of the orbit, the high-walled lamina orbitonasalis and densely-mineralised antorbital crest provide evidence for forward rotation of the jaw adductor musculature. Preserved foramina for the efferent superficial ophthalmic nerves show that the sensory organs on the rostrum were enervated in a manner similar to modern sharks, with the ophthalmic nerves not enclosed in an ethmoid canal, as in modern holocephalans. The conjunction of numerous distinctly holocephalan features with those that are otherwise general to Chondrichthyes demonstrates a decoupling of several of the structural conditions that characterise the distinctive morphological complex of the extant holocephalan skull. The anguiliform postcranium is more elongate than previously reconstructed, and it is now clear that the axial skeleton extended beyond the posterior extremity of the elongate dorsal fin. Morphological characters are reviewed with a view to further phylogenetic analyses. We recommend using the appearance of Chondrenchelys at 336.5 Ma as a hard minimum age for the last common ancestor of elasmobranchs and chimaeroids, because of its secure association with other holocephalans, and current uncertainties concerning elasmobranch stem lineage membership.

This study is concentrated on Ludlow (to Pridoli?) miospores from the Los Espejos Formation at the Quebrada Ancha locality, Central Precordillera, San Juan Province, Argentina. The Ludlow age is in agreement with the age based on acritarchs. The assemblage of continental palynomorphs is composed of 43 miospore species (29 trilete spores and 14 cryptospores). A new synonymy is proposed: Chelinospora poecilomorpha is here considered a junior synonym of Clivosispora verrucata. In addition, specimens belonging to C. verrucata var. verrucata and C. verrucata var. convoluta are included in a new morphon. This study represents the second Late Silurian miospore assemblage described from South America; the first was from the Urubu River, Amazon Basin, northern Brazil. The Quebrada Ancha assemblages allow a reasonably good correlation with biozones established for the Upper Silurian from the Cantabrian Mountains, northern Spain. The dendrogram analysis between coeval miospore assemblages from different localities shows a strong palaeogeographic affinity with the miospores recovered from northern Brazil and North Africa. Miospore assemblages from Spain show influences from Baltica and North Africa, demonstrating their intermediate position between these two continental plates. Conversely, dissimilarities recognized between Libya and Tunisia are most probably owing to local ecology and/or environmental conditions.

The morphologies of the hyobranchial apparatus in early tetrapods are reviewed, based primarily on first-hand examination and supplemented by published descriptions. The basic arrangement of the “aquatic” hyobranchium, with four pairs of branchial arches and internal gills, was conserved to a remarkable degree across the fish–to–tetrapod transition and was retained in further evolution in adults of several tetrapod lineages. Thus, a fish-like hyobranchium in basal tetrapods does not necessarily represent a larval or paedomorphic character, respectively, as was often suggested in analogy to extant salamanders. Rather, it represents the plesiomorphic state of the adult hyobranchium in tetrapods. The changes in the hyobranchium during the fish–to–tetrapod transition include the reduction of the number of skeletal elements and their morphological simplification. In all three presently discussed scenarios of lissamphibian origin, the temnospondyl, lepospondyl and diphyly hypotheses, the internal gills were reduced independently within temnospondyls and on the amniote stem below seymouriamorphs. Evidence of remodelling into a true “terrestrial” hyobranchium, with reduction of the posterior branchial arches and modification to support terrestrial tongue feeding, is scarce in early tetrapods. It evolved within temnospondyls in zatracheids, amphibamids and lissamphibians, as well as once or several times in early amniotes or in their immediate stem-forms.

Normalograptus kufraensis sp. nov. occurs as monospecific assemblages in the Tanezzuft Formation at the western margin of the Kufra Basin (Jabal Eghei), southern Libya. These graptolites have parallel-sided rhabdosomes with long, straight virgellae, climacograptid thecae and a full straight median septum. N. kufraensis is intermediate between Ordovician graptolites from the N. angustus (Perner) lineage and the younger sister species N. ajjeri (Legrand) and N. arrikini Legrand. N. kufraensis differs from these taxa as follows: it is broader than N. angustus; it has greater thecal spacing than N. ajjeri or N. arrikini. A table comparing measurements of N. kufraensis with 44 other Normalograptus taxa differentiates it from other members of this morphologically conservative group. Even though N. angustus and N. ajjeri are very long-ranging graptolites, a stratophenetic approach suggests that the specimens from Jabal Eghei may be of late Hirnantian or younger age. The faunal composition and preservation suggests these graptolites occupied the ‘cratonic invader’ biotope. The stratigraphic succession records deglacial flooding and fluctuating of redox in the Tanezzuft Formation, with the graptolites indicating a short-lived interval of anoxia.

A single specimen of a new species of the synziphosurine Kasibelinurus Pickett, 1993 is described from the Lower Devonian (Lochkovian) Xiaxishancun Formation of Yunnan Province, China. The new species, K. yueya sp. nov., extends the geographic extent of the family Kasibelinuridae from the Australian palaeocontinent to the South China palaeocontinent, and the stratigraphic range back some 50 Ma from Late to Early Devonian.

Numerous Variscan syntectonic calcite veins cross-cut Palaeozoic rocks in the Moravian Karst. A structural, petrographic and stable isotopic analysis of the calcite veins and a microthermometric study of fluid inclusions in these vein cements have been carried out to determine the origin of the Variscan fluids and their migration during burial and deformation. The isotopic parameters of white (older, more deformed) and rose (younger) calcites are: 87Sr/86Sr is between 0.7078 and 0.7082 (white) and 0.7086 (rose), δ18O is between +17.7 and +26.1 (white) and between +14.8 and +20.7 ‰ SMOW (rose), δ13C ranges from +0.1 to +2.5 (white) and from −0.3 to +1.6 ‰ V-PDB (rose). The isotopic signatures point to precipitation in an older fluid system buffered by the host rock (white calcites) and to an open, younger fluid-dominated system (rose calcites). Parent fluids (H2O–NaCl system) had salinities between 0.35 and 17.25 eq. wt % NaCl. The pressure-corrected and confined homogenization temperatures suggest formation of the calcite veins from a fluid with a temperature between 120 and 170 °C, a pressure of 300–880 bar at a depth between 2.1 and 3.2 km. The fluids were most likely confined to a particular sedimentary bed as a bed-scale fluid migration (white older calcite veins) or, later, to a pile of Palaeozoic sediments as a stratigraphically restricted fluid flow (rose younger calcite veins). The low temperatures and pressures during precipitation of calcites, which took place close to a peak of burial/deformation, confirm the distal position of the Moravian Karst region within the Variscan orogen.

Rb-Sr ages of Swanson Formation on Edward VII Peninsula, West Antarctica, indicate a late Ordovician age, 421–432 Ma for regional metamorphism. K-Ar ages of 113–440 Ma, reflect a second thermal metamorphism during emplacement of widespread Cretaceous granites. Rb-Sr ages of five monzogranite/syenogranitic plutons of Byrd Coast Granite are in the range 95–105 Ma (initial 87Sr/86Sr ratios 0.710–0.715) and represent stages of crystallization of anorogenic granite (A subtype). These correlate with Byrd Coast Granite (100–110 Ma) farther east in Marie Byrd Land, and with Cretaceous granitoids on the Campbell Plateau and in southern New Zealand. K-Ar mica/hornblende and fission-track apatite/zircon ages indicate that regional cooling began c. 90–100 M.y. ago immediately after granite emplacement. Uplift continued throughout the peninsula during the period 55–100 Ma (late Cretaceous-early Tertiary), associated with regional uplift in the rift-drift stages of Gondwana break-up at the South-west Pacific spreading centre. Apatite fission track ages show that during late Cretaceous-early Tertiary time the peninsula behaved as two blocks. The Alexandra Mountains were exhumed 20 m.y. before the Rockefeller Mountains and are possibly separated by a fault active initially in the mid-Cretaceous or earlier, and later reactivated in the late Cretaceous-early Tertiary. An averaged uplift rate (50–100 Ma) of 0.025 mm yr−1 is characteristic of the inferred intraplate tectonic setting.

The Maures Massif forms an important piece of the southernmost part of the Variscan belt of western Europe. This massif exhibits high-grade bimodal felsic–basic volcanic complexes, a distinctive lithological feature documented elsewhere in similar domains of the European Variscides and referred to the Cambro-Ordovician extensional episode. Two major alkalic and tholeiitic compositional groups and subordinate transitional metabasites have been identified, occurring at several distinct horizons or in bimodal complexes. This chemical diversity is interpreted in terms of variable degrees of partial melting of progressively depleted mantle source(s), which experienced melting at different depths, from garnet to spinel stability domains, during a progressive mantle upwelling associated with intracontinental rifting. This setting is reinforced by the presence of metabasites with compositions similar to continental flood basalts, showing slightly humped REE patterns, and interpreted as resulting from the melting of a partially depleted source at a relatively low degree of melting, in the garnet–spinel transition zone. The metafelsites from the tholeiitic bimodal complex exhibit the distinctive major and trace element characteristics of A-type rhyolites. Their elemental variations are consistent with fractional crystallization of major and accessory phases, but some discontinuous REE profiles result from a hydrothermal fractionation mechanism. The modelling of common anhydrous fractionating assemblages suggests that these A-type compositions may be derived from the associated tholeiites by extensive degrees of fractionation (90 %) with some continental crust involvement, or by anhydrous partial melting (∼30 %) of an underplated mafic parent of tholeiitic composition. The bimodal character of the Late Cambrian Maures magmatism, together with the chemistry of the various metabasites and metafelsites, suggests plume-induced intracontinental magmatic activity, resulting in lithospheric thinning prior to the onset of rifting and break-up of the Palaeozoic continental lithosphere, at this northern margin of Gondwana.