A review of biodiversity curves of marine organisms indicates that, despite fluctuations in amplitude (some large), a large-scale, long-term radiation of life took place during the early Palaeozoic Era; it was aggregated by a succession of more discrete and regionalized radiations across geographies and within phylogenies. This major biodiversification within the marine biosphere started during late Precambrian time and was only finally interrupted in the Devonian Period. It includes both the Cambrian Explosion and the Great Ordovician Biodiversification Event. The establishment of modern marine ecosystems took place during a continuous chronology of the successive establishment of organisms and their ecological communities, developed during the ‘Cambrian substrate revolution’, the ‘Ordovician plankton revolution’, the ‘Ordovician substrate revolution’, the ‘Ordovician bioerosion revolution’ and the ‘Devonian nekton revolution’. At smaller scales, different regional but important radiations can be recognized geographically and some of them have been identified and named (e.g. those associated with the ‘Richmondian Invasion’ during Late Ordovician time in Laurentia and the contemporaneous ‘Boda event’ in parts of Europe and North Africa), in particular from areas that were in or moved towards lower latitudes, allowing high levels of speciation on epicontintental seas during these intervals. The datasets remain incomplete for many other geographical areas, but also for particular time intervals (e.g. during the late Cambrian ‘Furongian Gap’). The early Palaeozoic biodiversification therefore appears to be a long-term process, modulated by bursts in significant diversity and intervals of inadequate data, where its progressive character will become increasingly clearer with the availability of more complete datasets, with better global coverage and more advanced analytical techniques.

The concept of the Tommotian Regional Stage of the Siberian Platform has been closely linked to the idea of the ‘Cambrian Explosion’ of animals and protists when the entire Earth system shifted rapidly into Phanerozoic mode. We conducted a multidisciplinary study of an informal ‘synstratotype’ of the lower Tommotian boundary in the upper Mattaia Formation, Kessyusa Group in the Olenek Uplift, NE of the Siberian Platform. The Mattaia Formation characterizes an upper shoreface to inner-shelf depositional setting and provides important faunal ties and correlation with carbonate-dominated and aliminosiliciclastic open-shelf areas. A section of the upper Mattaia Formation at Boroulakh, Olenek River is suggested here as a model for the Global Boundary Stratotype Section and Point for the base of the Cambrian Stage 2. This level contains the lowermost occurrence of the cosmopolitan fossil helcionelloid mollusc Aldanella attleborensis. Section global markers near the base of the stage include a positive excursion of δ13C values reaching +5.4‰, a U–Pb zircon date of 529.7 ± 0.3 Ma, massive appearance of diverse small skeletal fossils (including Watsonella crosbyi), a sudden increase in diversity and abundance of trace fossils, as well as a conspicuous increase in depth and intensity of bioturbation. Coincidently, it is this level that has always been regarded as the lower Tommotian boundary on the Olenek Uplift.

Trilobites are an iconic group of extinct arthropods that lived in Palaeozoic oceans for c. 270 Ma, before their demise at the end of the Permian Period. Despite their considerable diversity (> 22 000 species) and abundance, particularly in Cambrian and Ordovician rocks, as well as intensive study for well over 200 years, trilobite systematics remains in a state of flux. In this contribution, the complex history of trilobite classification over the last century is briefly reviewed, including the seminal scheme published by Henry Swinnerton in 1915. The cryptogenesis problem, which relates to the supposedly obscure phylogenetic links between major post-Cambrian trilobite clades and their Cambrian sister taxa, is also discussed. Previous studies have suggested that the cryptogenesis problem is largely a taxonomic artefact, but the Cambrian origins of some post-Cambrian groups, such as the orders Proetida and Odontopleurida, are still unclear. Future directions for research on trilobite systematics are outlined, from taxonomic studies involving comprehensive documentation and extensive illustration of morphology at the species level, through to broad-scale phylogenetic analyses that initiate or test hypotheses about relationships across the major groups. Other ongoing issues to be addressed include identifying the sister group of Trilobita, and determining whether certain taxa, such as the suborder Agnostina and Cambrian family Burlingiidae, represent trilobites.

The terrestrialization of life has profoundly affected the biosphere, geosphere and atmosphere, and the Geological Magazine has published key works charting the development of our understanding of this process. Integral to this understanding – and featuring in one of the Geological Magazine publications – is the Devonian Rhynie chert Konservat-Lagerstätte located in Aberdeenshire, Scotland. Here we provide a review of the work on this important early terrestrial deposit to date. We begin by highlighting contributions of note in the Geological Magazine improving understanding of terrestrialization and Palaeozoic terrestrial ecosystems. We then introduce the Rhynie chert. The review highlights its geological setting: the Caledonian context of the Rhynie Basin and its nature at the time of deposition of the cherts which host its famous fossils. There follows an introduction to the development of the half-graben in which the cherts and host sediments were deposited, the palaeoenvironment this represented and the taphonomy of the fossils themselves. We subsequently provide an overview of the mineralization and geochemistry of the deposit, and then the fossils found within the Rhynie chert. These include: six plant genera, which continue to provide significant insights into the evolution of life on land; a range of different fungi, with recent work starting to probe plant–fungus interactions; lichens, amoebae and a range of unicellular eukaryotes and prokaryotes (algae and cyanobacteria); and finally a range of both aquatic and terrestrial arthropods. Through continued study coupled with methodological advances, Rhynie fossils will continue to provide unique insights into early life on land.

The Lung Cam expanded stratigraphic succession in Vietnam is correlated herein to the Meishan D section in China, the GSSP for the Permian–Triassic boundary. The first appearance datum of the conodont Hindeodus parvus at Meishan defines the Permian–Triassic boundary, and using published graphic correlation, the Permian–Triassic boundary level has been projected into the Lung Cam section. Using time-series analysis of magnetic susceptibility (χ) data, it is determined that H. parvus arrived at Lung Cam ∼18 kyr before the Permian–Triassic boundary. Data indicate that the Lung Cam section is expanded by ∼90 % relative to the GSSP section at Meishan. Given the expanded Lung Cam section, it is possible to resolve the timing of significant events during the Permian–Triassic transition with high precision. These events include major stepped extinctions, beginning at ∼135 kyr and ending at ∼110 kyr below the Permian–Triassic boundary, with a duration of ∼25 kyr, followed by deposition of Lung Cam ash Bed + 13, which is equivalent to Siberian Traps volcanism is graphically correlated to a precession Time-series model, placing onset of this major volcanic event at ~242 kyr before the PTB. The Meishan Beds 25 and 26, at ∼100 kyr before the Permian–Triassic boundary. In addition, the elemental geochemical, carbon and oxygen isotope stratigraphy, and magnetostratigraphy susceptibility datasets from Lung Cam allow good correlation to other Permian–Triassic boundary succession. These datasets are helpful when the conodont biostratigraphy is poorly known in sections with problems such as lithofacies variability, or is undefined, owing possibly to lithofacies exclusions, anoxia or for other reasons. The Lung Pu Permian–Triassic boundary section, ∼45 km from Lung Cam, is used to test these problems.

Regional to global high-resolution correlation and timing is critical when attempting to answer important geological questions, such as the greenhouse to icehouse transition that occurred during the Eocene–Oligocene boundary transition. Timing of these events on a global scale can only be answered using correlation among many sections, and multiple correlation proxies, including biostratigraphy, lithostratigraphy, geochemistry and geophysical methods. Here we present litho- and biostratigraphy for five successions located in the southeastern USA. To broaden the scope of correlation, we also employ carbon and oxygen stable isotope and magnetic susceptibility (χ) data to interpret these sections regionally, and correlate to the Global Boundary Stratotype Section and Point (GSSP) near Massignano in central Italy. Our results indicate that approaching the Eocene–Oligocene boundary, climate warmed slightly, but then δ18O data exhibit an abrupt c. +5 ‰ positive shift towards cooling that reached a maximum c. 1 m below the boundary at St Stephens Quarry, Alabama. This shift was accompanied by a c. −3 ‰ negative shift in δ13C interpreted to indicate environmental changes associated with the onset of the Eocene–Oligocene boundary planktonic foraminiferal extinction event. The observed cold pulse may be responsible for the final extinction of Hantkeninidae, used to define the beginning of the Rupelian Stage. Immediately preceding the boundary, Hantkeninidae species dropped significantly in abundance and size (pre-extinction dwarfing occurring before the final Eocene–Oligocene extinctions), and these changes may be the reason for inconsistencies in past Eocene–Oligocene boundary placement in the southeastern USA.

Metamorphic core complexes (MCCs) are interpreted as domal structures exposing ductile deformed high-grade metamorphic rocks in the core underlying a ductile-to-brittle high-strain detachment that experienced tens of kilometres of normal sense displacement in response to lithospheric extension. Extension is supposedly the driving force that has governed exhumation. However, numerous core complexes, notably Himalayan, Karakoram and Pamir domes, occur in wholly compressional environments and are not related to lithospheric extension. We suggest that many MCCs previously thought to form during extension are instead related to compressional tectonics. Pressures of kyanite-and sillimanite-grade rocks in the cores of many of these domes are c. 10–14 kbar, approximating to exhumation from depths of c. 35–45 km, too great to be accounted for solely by isostatic uplift. The evolution of high-grade metamorphic rocks is driven by crustal thickening, shortening, regional Barrovian metamorphism, isoclinal folding and ductile shear in a compressional tectonic setting prior to regional extension. Extensional fabrics commonly associated with all these core complexes result from reverse flow along an orogenic channel (channel flow) following peak metamorphism beneath a passive roof stretching fault. In Naxos, low-angle normal faults associated with regional Aegean extension cut earlier formed compressional folds and metamorphic fabrics related to crustal shortening and thickening. The fact that low-angle normal faults exist in both extensional and compressional tectonic settings, and can actively slip at low angles (< 30°), suggests that a re-evaluation of the Andersonian mechanical theory that requires normal faults to form and slip only at high angles (c. 60°) is needed.