This paper draws on epistemology, theory, published data, hypothesis testing and synthesis to explore the predictive and explanatory power of a far-from-equilibrium interpretation of the history of human settlement on Rapa Nui. Our interpretation of the last 1500 years of human settlement on Rapa Nui provides an important competing hypothesis by which to test the explanatory power of earlier equilibrium interpretations of this history. Our evaluation of this competing hypothesis suggests that it provides, overall, a more satisfactory theory that has interesting implications for the goal of sustaining human civilisation.

Earliest Silurian (basal Llandovery) brachiopod faunas are surveyed and listed from around the globe, and divided between Lower Rhuddanian and Upper Rhuddanian occurrences. 60 genera are known from the Lower Rhuddanian within 20 superfamilies and there are 87 genera in 25 superfamilies in the Upper Rhuddanian. The 29 areas surveyed span the globe, both latitudinally and longitudinally. Only six superfamilies are Lazarus taxa which are known both from the Ordovician and Middle Llandovery (Aeronian) and later rocks but have not been recorded from the Rhuddanian. These are surprising results, since many previous studies have inferred that the Rhuddanian was a time of very sparse faunas. The global warming that followed the latest Ordovician (Hirnantian) ice age did not proceed quickly, with an ice-cap probably present through at least the Llandovery. There is a marked absence of Lower Rhuddanian bioherms even at low palaeolatitudes; however, the ecological recovery rate was far faster than that following the end-Permian mass extinction event. The partitioning of the Rhuddanian shelf faunas into well-defined benthic assemblages progressed slowly over the interval.

Holocene sea-level changes affected people living in the Pacific Islands and their ancestors along the western Pacific Rim. Sea-level changes, particularly those that were rapid, may have led to profound and enduring societal/lifestyle changes. Examples are given of (1) how a rapid sea-level rise (CRE-3) about 7600 BP could ultimately have led to the earliest significant cross-ocean movements of people from the western Pacific Rim into the islands; (2) how mid to late Holocene sea-level changes gradually created coastal environments on Pacific Islands that were highly attractive to human settlers; (3) a hypothesis that rapid sea-level fall during the ‘AD 1300 Event' brought about widespread disruption to trajectories of cultural evolution throughout the Pacific Islands; and (4) the effects of recent and likely future sea-level rise on Pacific Island peoples.

Ultrastructural examination of the brachiopod Thecidellina from three different locations in the Caribbean and the Atlantic revealed that at least three cryptic species are present. One is the type species of the genus, Thecidellina barretti, which may only occur in Jamaica. The other two, previously lumped into T. barretti, are new to science, viz T. bahamiensis Lüter & Logan sp. nov. from the Bahamas and T. williamsi Lüter & Logan sp. nov. from Cape Verde. All three species clearly differ not only in their provenance, but also in specific shell characters, such as spiculation of the ventral valve, presence of a ventral median ridge, shape of two holes in the intrabrachial ridge of the dorsal valve and the structure of the interbrachial lobes. The identification of three instead of a single species and their supposed allopatric speciation is discussed with regard to the thecideide life cycle and independent models of larval dispersal in the Caribbean, based on oceanographic data.

A new rhynchonellide brachiopod has been collected from the Kahuitara Tuff (Campanian–Maastrichtian) of Pitt Island, Chatham Islands, New Zealand. Brachiopods are extremely rare in Cretaceous rocks from New Zealand, and this new genus and species is unlike any other rhynchonellide known from Australasia or elsewhere. Chathamirhynchia kahuitara is distinguished by its small size, strong ribbing, and well-developed sulciplicate folding, and internally by a large, robust cardinal process and raduliform crura. The shell structure of C. kahuitara is shown to be of typical fine fibrous ‘rhynchonellidine’ type. This brachiopod was probably strongly attached to volcanic rock or shells in a shallow-water, high-energy environment. Implications for the biogeography of brachiopods during the Late Cretaceous are briefly discussed.

A review is presented of the genera and species, both living and fossil, comprising the Superfamily Kraussinoidea and of their geographic and stratigraphic distributions. Two new fossil species are described, Kraussina chilensis and Megerlina miracula, from the Miocene of Chile and New Zealand respectively. The ontogenetic development of the brachidium in each of the four kraussinid genera is described and on the basis of recognised differences it is proposed that a new taxonomic subdivision is made that places Megerlia in a new subfamily Megerliinae, distinct from the other three genera in the existing subfamily Kraussininae Dall. The loop ontogeny of kraussinoids is compared with that of other terebratellidines and a phylogenetic linkage between kraussinoids and laqueoids is suggested.

This study explores the implications of different decisions about taxon sampling in studies of phylogeny and macroevolution – how would phylogenetic results differ as decisions about inclusion of taxa differed? The focus is on investigating phylogenetic relationships among families of Devonian terebratulides, and include all 71 named genera in our analyses. Subsets of taxa were experimented with the most complete morphologically from fossil specimens; those that occur earliest in the stratigraphic record; those that include only the name-bearing genera from each family. Including only the most completely known genera produces a result essentially similar to one including all genera, even those for which less than half the characters can be coded. Including only the stratigraphically earliest genera produces a result at odds with the other analyses. Including only name-bearers, representing 13% of all genera, produces a result generally similar to the analysis including all taxa. None of the results of these phylogenetic experiments involving subsets of genera corresponds strongly with the recently revised classification in the Treatise on Invertebrate Paleontology, but general similarities can be discerned. The lack of strong correspondence between classification and several different experimental phylogenetic hypotheses could be ascribed to their different overall goals, and highlights the potential dangers of ascribing evolutionary significance to simple counts of taxa, particularly families, as warned by Alwyn Williams 50 years ago.

A new genus of pentameride brachiopod, Costilamnulella, described herein from the middle Ashgill of Sweden, is particularly interesting in that the ventral valve possesses both an interarea and a palintrope. Brachiopods normally have one or the other, but both structures do occur amongst the pentamerides, e.g. in Clorinda, Anastrophia and Brevilamnulella. The presence of these structures in three separate pentameride families indicates the persistence of the more primitive condition of an interarea whilst the more advanced palintrope is becoming established. Costilamnulella is interpreted as a restricted side line of the main development of the more widely occurring Brevilamnulella, which survived the end-Ordovician event and may have shared its ancestry with the ubiquitous Clorinda.

The lower Meitan Formation (Floian, upper Lower Ordovician) at the Dajiaosi section, Zunyi District, northern Guizhou Province of South China, contains a moderately rich and diverse Sinorthis Fauna, with 22 species attributable separately to 15 families and seven orders of brachiopods. The fauna can be differentiated into three associations: the Paralenorthis serica, the Sinorthis typica, and the Tarfaya intercalare associations. These occupied a relatively wide palaeoecological range from lower BA3 to upper BA2 settings and from silty to clay substrate conditions. In South China, the Early Ordovician brachiopod radiation was marked by the diversification of the orthide-dominated Sinorthis Fauna, which first appeared and diversified in the middle part (relatively deep water) of the Upper Yangtze Platform in the Didymograptellus eobifidus Biozone, but rapidly declined in the succeeding Corymbograptus deflexus and basal Azygograptus suecicus biozones. During the latest Floian and early Dapingian, it expanded into comparatively shallow-water settings in the onshore direction (Changning area, southern Sichuan), offshore carbonate platform (Yichang, Hubei), and areas adjacent to the submergent Qianzhong Arch (such as the Zunyi area). The first appearance datum of the Sinorthis Fauna in shallower-water settings generally postdates that in the deeper-water environment in the central Upper Yangtze Platform, probably as a result of the fauna tracking a favoured BA3 setting during a gradual marine transgression.

Locally abundant and diverse brachiopod faunas, associated with unstable outer shelf and slope environments, occur throughout the Barr and Ardmillan groups (middle Llanvirn–upper Ashgill) in the Girvan district of SW Scotland. A dataset of 350 brachiopod species from 30 horizons through the Middle–Upper Ordovician succession forms the basis for a description of brachiopod diversity through the succession and comparison with global patterns and trends through this time interval. The Middle Ordovician Barr Group incorporates shallow water carbonate and clastic facies, characterised by Valcourea confinis, with deeper-water facies. The trilobite-dominated Albany Group preserves outer shelf biofacies. Deep-water facies occur in the Balclatchie Formation of the lower Ardmillan Group, including an early occurrence of a Foliomena-type species. High diversity brachiopod faunas occur in clastic facies, though many of the biofacies have a transported component to them. Representatives of the deep-water Foliomena fauna occur intermittently throughout the Upper Ardmillan Group, appearing in both the Whitehouse and Drummuck subgroups. This distinctive assemblage of small, thin-shelled brachiopods, including Dedzetina, Christiania, Cyclospira and Foliomena itself, is interbedded with a variety of other less cosmopolitan deep-water assemblages, including the Onniella–Skenidioides and Lingulella–Trimurellina associations. Shallower-water environments in the middle Ashgill Lower Drummuck Subgroup hosted the Fardenia–Eopholidostrophia association in sands, and the Christiania–Leptaena association in muds and silts. The remarkable Lady Burn Starfish Beds in the upper part of the group contain a variety of brachiopod-dominated assemblages, including the Eochonetes and Plaesiomys–Schizophorella associations, transported from various shelf locations, within a very diverse mid Ashgill biota. The upper Ashgill High Mains Formation contains abundant elements of the terminal Ordovician Hirnantia fauna, including Eostropheodonta, Hindella and Hirnantia itself, but also some taxa more typical of the Laurentian Edgewood Province. As a whole, the changing brachiopod biodiversity biofacies reflect environmental fluctuations, on this part of the Laurentian margin, driven by mainly eustatic and tectonic events against a background of global biotic radiation.

We consider the reinterpretation of Bethia by Bassett et al. (2008) to be flawed in several regards. Details of the pedicle rootlets and wrinkles strongly imply a soft-tissue structure rather than calcified sheath. The ornament is unusual, but equally so under either an orthide or a plectambonitoidean model. The reinterpretation of the ‘deltial plates’ as ‘chilidial plates’ is likely correct, but argues against a plectambonitoidean affinity by implying that the pedicle emerges between the valves. Other arguments presented in favour of a plectambonitoidean affinity are also discussed; we consider them unpersuasive. Finally, we contend that Bethia is sufficiently well characterised to deserve a taxonomic name.

Electron backscatter diffraction (EBSD) is used to determine the detailed crystallographic orientation of calcite crystals of craniid brachiopods in the context of shell ultrastructure. Sections of shells of two Recent species, Novocrania anomala and Novocrania huttoni, are analysed to provide 3D crystallographic patterns at high spatial resolution. The c-axis of semi-nacre calcite crystals is oriented parallel to the laminae that define the ultrastructure of the secondary layer. This orientation differs from that of rhynchonelliform calcitic brachiopods where the c-axis is perpendicular to the length of morphological fibres and to the shell exterior.

Siphonotretid brachiopod distribution in the Lower Ordovician of the Prague Basin is described and discussed; the new species Alichovia cometa is established. The preservation and distribution of the group indicate a preference for shallow-water offshore, high-energy environments: siphonotretids are abundant shelly fossils in the shallower-water, mostly marginal sites of the basin but are absent in the deeper parts. Their environmental limits were complementary to those of the graptolites; siphonotretids co-occur with epiplanktonic graptolites at only a few localities. Deeper offshore deposits with biramose dichograptids and diverse, generally delicate benthic dendroids lack siphonotretids. Indeed, siphonotretids were intolerant to dysoxia and preferred a well-aerated siliciclastic, firm sea floor in the shallower parts of the basin. They were tolerant to suspended coarser detritus, using their spines which functioned as an effective sieve. The density and ramification of spines indicate three sifting strategies. Suggested life styles above the seabed on elevated surfaces (algae, sponges, dendroids) are not supported by direct evidence. They more likely lived within more supple and soft matrices (sponges, tufts of algae) stabilised by their spines, with the spinose basket maintaining free space for inhalant and exhalant currents.

The size of the protegulum on the valves of Early Palaeozoic rhynchonelliform brachiopods has previously been used as a criterion to assign various taxa to either a planktotrophic or a lecithotrophic larval mode. A more reliable quantitative character is evaluated in juvenile samples of two genera from the Ordovician Mifflin Formation, the presumed planktotrophic orthid Doleroides pervetus and the presumed lecithotrophic atrypid Protozyga nicolleti, using the coefficient of variation in measurements of protegular size. The Doleroides sample has a significantly higher coefficient of variation than does the Protozyga sample. The results are in accord with observations on living marine invertebrates which indicate that at settlement (when mineralisation of the protegular mantle in brachiopods occurs), planktotrophic larval size is more variable than larval size in lecithotrophs because of fluctuations in food availability and duration of the planktonic phase. This result confirms that protegular size variance can be used to make inferences about larval trophic mode.

This paper describes a terebratelloid articulate brachiopod, Gyrothyris williamsi sp. nov., based on 95 specimens from seamounts on the Lord Howe Rise, Coral Sea, SW Pacific Ocean. The new species is attributed to Gyrothyris on the basis of (a) morphological and growth trajectory similarities; (b) phylogenetic analyses of an alignment of DNA sequence (∼2900-sites) obtained from nuclear-encoded small- and large-subunit ribosomal RNA genes (SSU and LSU); and (c) the presence of a distinctive, two-part deletion in the LSU gene. It is distinguished morphologically from Gyrothyris mawsoni and its subspecies by both internal and external morphology and by its isolated geographical distribution, which extends the patchy, known range of this genus to an area some 2000 km north of its previous northern limit around New Zealand. Phylogenetic analyses of the rDNAs and of mitochondrial cox1 gene sequences (663 sites) confirm previous indications that the New Zealand endemic terebratelloid genera form a clade (Neothyris (Calloria, Gyrothyris, Terebratella), but the position of Terebratella with respect to Calloria and Gyrothyris remains weakly established. These sequences disagree inexplicably about the closeness of the relationship between Neothyris parva and N. lenticularis. Analyses of the first sequences from Calloria variegata, a species restricted to the Hauraki Gulf, New Zealand, are consistent with the possibility that it originated locally, and recently, from C. inconspicua. Magellania venosa from S. America/Falklands joins with Antarctic Magellania fragilis and M. joubini to form an rDNA clade that excludes Terebratalia as the putative sister-group of the New Zealand terebratelloid clade. The cox1 (but not the rDNA) sequences of the New Zealand clade pass a test for clock-like rates of evolution, and maximum likelihood pairwise distances suggest that if genetic isolation between the ancestor of Antarctic Magellania and the last common ancestor of the New Zealand terebratelloid clade was initiated by separation of the Antarctic and New Zealand plates ∼90 Mya, isolation from M. venosa was initiated earlier, perhaps ∼145 Mya. However, in the simple phylogenetic reconstruction presented here from cox1 sequences, S. American and Antarctic Magellania spp. do not yield a well-supported clade, perhaps because of differences in base composition.

This study describes bioerosion traces ascribed to either predation or endo- and epibiont activity in twenty assemblages from the Mediterranean region and Paratethys, spanning in age from Eocene to Recent. Statistical analysis of the distribution of bioerosion traces among genera and assemblages revealed that there is higher drilling predation intensity on smaller species. Larger species seem to be primarily affected by non-drilling predators. Greatest variety in types of bioerosion could be related to species’ ecology and body size. Both major categories of bioerosion (etchings and traces of predatory activity) vary considerably among samples. Different genera show significant differences in the frequency of different bioerosion types. Shell size seems a major factor contributing to these differences.

Spire-bearing brachiopods formally comprise four different rhynchonelliform orders. A calcified spiral brachidium (presumably supporting a spirolophe when alive) and variable median fold and sulcus (probably aiding separation of incurrent from excurrent flows) are peculiar characteristics they all share. Inferences regarding feeding current systems for these extinct taxa have long remained controversial. Two rival models (the Williams–Ager model and the Rudwick–Vogel model) have been developed, each of which has gained supporters as well as critics over the years. In this present paper they are both contrasted and reassessed on the basis of available evidence, together with a new approach that combines: (a) a morpho-functional analysis applying the plankton net as a suitable seston-collecting paradigm; (b) a review of actualistic data showing that all extant spirolophes are functionally inhalant (irrespective of water entering the valves laterally or not); (c) an evaluation of known outcomes from flume experiments yielding consistent empirical results where gaping shells are oriented transversally and dorsally upcurrent; and (d) a reappraisal of the distributions of certain epizoobionts and endosymbionts revealing compatible patterns. The evidence thus accumulated supports the main conclusion that, in most groups (with laterally tapering spiralia), the inhalant current was located medially with the exhalant currents on either side; only in atrypides (with centrally to dorsally tapering spiralia) does the reverse situation appear to have occurred.

Animals can respond in three main ways to environments that change and deteriorate. They can cope with their inherent physiological flexibility, evolve or adapt to new conditions, or migrate away to areas consistent with survival. The main factors dictating survival are the rates of change and capacities of species to cope. Articulated brachiopods are known as a group that employ low energy solutions and exhibit slow rates in life histories characters, especially in growth and metabolic rates. This way of life carries with it a range of consequences, including poor abilities to raise metabolic rates to perform work. This brings with it poor abilities to cope with elevated temperature. Slow growth, deferred maturity and low feeding rates make them less likely to produce novel adaptations compared with other marine invertebrate taxa. Being largely restricted to hard substrata and low energy supply environments also makes it harder for them to migrate to new sites compared to other groups, because of the large geographic distances between colonisable areas. The only clear area they may have that gives them advantages is in the flexibility of their larval release strategies, where settlement can be from very short, millimetre-scale distances to hundreds of kilometres.

This two-part special issue, Brachiopod Research into the Third Millennium, is published in honour of Sir Alwyn Williams (8 June 1921–4 April 2004). One section deals with fossil brachiopods while the other concentrates on aspects of modern material. The special issue comprises 23 invited papers, all dealing with current brachiopod research. In producing this special issue we honour the immense contribution made by the late Alwyn Williams to this field of research.