U-Pb zircon geochronology of Mesoproterozoic (Subjotnian) rapakivi complexes in central Sweden yields: 1526 ± 3 Ma (Mullnäset), 1524 ± 3 Ma (Mårdsjö), 1520 ± 3 Ma (Nordsjö) and 1497 ± 6 Ma (Rödön). Together with complexes further S in Sweden, they constitute the westernmost, youngest (1·53−1·47 Ga) belt of rapakivi magmatism in the Fennoscandian shield.

The low initial εNd values (−8·9 to −4·8) of all studied Subjotnian basic, intermediate and silicic rocks, require an input from an old (Archaean) low-radiogenic source component, as evidence for Palaeoproterozoic protoliths in the age range 2·5−2·1 Ga is lacking in this region. Crustal, early Svecofennian + Archaean (roughly 30−40%) sources are suggested for the Subjotnian A-type granites and syenites, where the granites derive from undepleted, granodioritic, and the syenites from monzodioritic (±depleted crustal) protoliths. The basic rocks originate from a depleted mantle acquiring the enriched Nd isotopic signatures during interaction with an Archaean lower crust (20−40%), largely depleted after rapakivi melt extraction. Pb isotope data from feldspars (207Pb/204Pb to 15·018−15·542) support the presence of Archaean components in the magmas.

The results indicate that an Archaean basement is underlying relatively wide areas of Svecofennian formations in central Sweden. This old basement section was most likely rifted off the Archaean craton in the NE in Palaeoproterozoic times.

The tetrapod Caerorhachis bairdi, probably from the Pendleian Limestone Coal Group in the Scottish Midland Valley, is rediagnosed and redescribed, and its affinities are discussed. Caerorachis was originally interpreted as a temnospondyl amphibian, based on characters that are now regarded as primitive for tetrapods, or of uncertain polarity. Several features of Caerorhachis (e.g. gastrocentrous vertebrae, curved trunk ribs, reduced dorsal iliac blade, L-shaped tarsal intermedium) are observed in certain primitive amniotes. In particular, Caerorhachis resembles ‘anthracosaurs’, generally considered to be among the most primitive of stem-group amniotes.

The phylogenetic position of Caerorhachis is considered in the light of recently published cladistic analyses of Palaeozoic tetrapods. Most analyses place Caerorhachis at the base of, or within, ‘anthracosaurs’. When multiple, equally parsimonious solutions are found, its ‘anthracosaur’ affinities are shown in at least some trees, and are supported by several informative and, generally, highly consistent characters. Alternative phylogenetic placements (e.g. sister taxon to temnospondyls) are usually less well corroborated.

If the fundamental evolutionary split of most early tetrapods into stem-group lissamphibians (e.g. temnospondyls) and stem-group amniotes (e.g. ‘anthracosaurs’) is accepted, then the revised interpretation of Caerprhachis sheds light on near-ancestral conditions for Amniota.

The sculpture of scales and plates of articulated anaspids from the order Birkeniida is described and used to clarify the position of scale taxa previously left in open nomenclature. The dermal skeleton of a well-preserved squamation of Birkenia elegans Traquair, 1898 from the Silurian of Scotland shows a characteristic finely tuberculated sculpture over the whole body. Rhyncholepis parvula Kiær, 1911, Pterygolepis nitida (Kiær, 1911) and Pharyngolepis oblonga Kiær, 1911, from the Silurian of Norway show three other sculpture types. Northern Hemisphere disarticulated scales and plates are described here, supporting a new anaspid taxonomy that includes both articulated and disarticulated material. The diversity, distribution, evolutionary trends and biostratigraphy of anaspids are described in the context of this new taxonomy, which includes six families (two are new) subdivided into 16 genera (10 are new) and 22 species (15 are new).

New taxa among Birkeniidae Traquair, 1898 are Birkenia robusta sp. nov. and Hoburgilepis papillata gen. et sp. nov.. Rhyncholepididae Kiær, 1924 includes Rhyncholepis butriangula sp. nov., Silmalepis erinacea gen. et sp. nov., Vesikulepis funiforma gen. et sp. nov., Maurylepis lacrimans gen. et sp. nov., and the previously described Schidiosteus mustelensis Pander, 1856 and Rytidolepis quenstedtii Pander, 1856. Tahulalepididae fam. nov. is represented by Tahulalepis elongituberculata gen. et sp. nov. and the revised T. kingi (Woodward, 1947). Septentrioniidae fam. nov. contains Septentrionia lancifera gen. et sp. nov., S. mucronata gen. et sp. nov., S. dissimilis gen. et sp. nov., S. seducta gen. et sp. nov., Liivilepis curvata gen. et sp. nov., Spokoinolepis alternans gen. et sp. nov. and Manbrookia asperella gen. et sp. nov. The family level position of Ruhnulepis longicostata gen. et sp. nov. is uncertain. Pterygolepididae Obruchev, 1964 and Pharyngolepididae Kiær, 1924 remain monogeneric.

The first whipspider (Arachnida: Amblypygi) and three new examples of whipscorpions (Arachnida: Uropygi: Thelyphonida) are described from Lower Cretaceous (Aptian) strata of the Crato Formation, Ceará State, Brazil. The whipspider is described as Britopygus weygoldti gen. et sp. nov. It resembles members of the extant family Charinidae, but cannot be unequivocally placed. Two of the whipscorpions are referred to Mesoproctus rowlandi Dunlop, 1998 and one could be a subadult, since, like juveniles of extant species, it has a relatively broad anterior sternum. There are differences between these two specimens in pedipalp and flagellum morphology, but both characters are variable within extant species. The third and largest whipscorpion is incomplete and referred to Mesoproctus sp. Its carapace length is equal to or exceeds that of the largest known extant genus Mastigoproctus Pocock, 1894.

The fossiliferous bed in the Upper Comley Sandstone, described by Cobbold & Pocock (in 1934) as the ‘Paradoxides forchhammeri Grit’ and correlated by them with the Andrarum Limestone of the late Middle Cambrian (P. forchhammeri Stage) in Scandinavia, is shown to be a shallow-water development of the older punctuosus Zone (medial Middle Cambrian, P. paradoxissimus Stage). It is here re-named the ‘Rushton Brook Bed’. The trilobite fauna, formerly considered comparable with that of the Andrarum Limestone, is reviewed and found taxonomically distinct, the supposed similarities being attributable to facial and preservational factors.

This paper evaluates the taxonomy, biostratigraphy, and palaeogeographical significance of the Cambrian bradoriid arthropods of China, the majority of which occur in the lower Cambrian of SW China. Of bradoriid faunas world-wide, Chinese occurrences yield the greatest number of specimens and a comparatively high diversity at all taxonomic levels. Nevertheless, taxonomic diversity is much less than previously supposed. Some 80 bradoriid genera and nearly 300 species have been proposed on the basis of Chinese material. By contrast, in our study, which encompasses all of the important Chinese bradoriid faunas, we recognise only 16 genera and 21 species, including those treated under open nomenclature. Interpretation of deformed specimens as discrete species and lack of application of the rules of the International Code of Zoological Nomenclature resulted in taxonomic splitting and a proliferation of names. There are an additional 12 poorly known monotypic genera of uncertain systematic status that are listed but not treated further herein. One phosphatocopid species, a group originally thought closely related to the Bradoriida, is also described.

Most Chinese bradoriid material is known from Yunnan Province; the group also occurs in Guizhou, Henan, Hubei, Hunan, Liaoning, Qinghai, Shaanxi, Sichuan, Xinjiang and Zhejiang provinces. The first bradoriids occur just below the Abadiella trilobite Biozone. They are most prolific and diverse in the Qiongzhusian Stage, constituting the most abundant animal group; the succeeding Canglangpuian Stage contains fewer individuals and species. A previously proposed bradoriid biozonal scheme lacks rigour and is of little practical value: of the five supposed biozones, two correspond to trilobite zones and three are based on taxa that herein are considered to belong to a single species.

Palaeogeographically the bradoriids occur in the Middle and especially the Western subprovinces of the Cambrian of the SW China (Yangtze) Platform. Almost all of the bradoriid genera and species are endemic to that region. The palaeogeographical links with other bradoriid faunas are mostly within the Redlichiid trilobite Realm, with areas such as N China, Australia and parts of central Asia.