The village of Stolbovo, western Russia has previously yielded a dipnoan fauna comprising the long-snouted Rhinodipterus stolbovi but also a three-dimensionally preserved otoccipital region of a skull previously identified as the osteolepiform ‘Latvius obrutus’. This identification was made from the density of lateral line canal pores in the skull roof bones in addition to what Vorobyeva described as the post-parietal, tabular and extratabular bones. Reexamination of this specimen does not recognise the osteolepiform dermal elements previously identified but rather a dipnoan configuration including a characteristic B-bone, lateral dermal elements and a dipnoan parasphenoid. MicroCT-scanning reveals an enlarged utricular recess in the vestibular system, the derived condition for lungfishes, and separate sacculae and lagenae also present in rhinodipterid and dipterid dipnoans. Phylogenetic analysis resolves ‘Latvius’ obrutus as the primitive sister taxon to the ‘phaneropleurid-fleurantiid’ clade – a clade comprising derived Middle-Upper Devonian lungfishes. Rhinodipterus stolbovi resolves among the more primitive griphognathids, typical Gondwanan forms, and is not a rhinodipterid. Additional isolated dipnoan skeletal elements from the site include tooth plates, parasphenoids and dermal elements and indicate at least an additional three lungfish taxa from Stolbovo. Of particular note is a ctenodiform toothplate more characteristic of Carboniferous lungfishes. The new material and analyses not only demonstrate increased lungfish diversity from the Frasnian of Baltica but also probable interchange between Gondwana and Baltica. Most importantly, Carboniferous-like forms appear more common in the Devonian than previously realised indicating that Carboniferous lungfishes likely represent a survival assemblage in addition to a new radiation of lungfish.

Orovenator mayorum, from the early Permian (Sakmarian) of Oklahoma, has been described as the earliest representative of Neodiapsida, a clade that includes dinosaurs and birds, snakes, lizards, crocodiles and turtles. High-resolution CT scans of the two known specimens of this taxon reveal novel anatomical data. These include the arterial pathways in the basicranium and palate, the osseous canal enclosing the nasolacrimal duct, and well preserved septomaxillae. Exceptional detail of the cranial sutural anatomy is evident, including unusual medial buttressing on the lacrimal and maxilla which indicate a high structural integrity of the anteorbital region. By combining the elements of both specimens we have been able to reconstruct most of the skull in virtual 3-D, including a complete palate and basicranium. Several features of Orovenator are shared with Varanopidae, a generally accepted stem-ward clade of pelycosaur-grade synapsids. Substantial similarity between early diapsids and varanopid synapsids has previously been noted: four taxa currently assigned to the Varanopidae were originally described as diapsids (Archaeovenator, Heleosaurus, Apsisaurus) or archosauromorphs (Mesenosaurus). However, our study suggests that these similarities are greater than previously appreciated, raising questions about deep phylogenetic divergences within amniotes. Application of the new data on Orovenator into an existing phylogenetic matrix intended to discriminate between varanopids and diapsids resulted in an unresolved consensus. This has prompted work on a novel phylogeny, with greater taxonomic scope, to provide a working hypothesis for the interrelationships of Permo-Carboniferous amniotes.

Fusion in the vertebral column occurs normally in jawed vertebrates, with structures like the sacrum and pygostyle providing rigidity, support and increased area for muscle attachment. The synarcual represents the fusion of the anterior part of the vertebral column and occurs in a number of jawed vertebrates, including a variety of placoderms and chondrichthyans. Placoderms are an entirely fossil group of armoured fishes (Silurian-Devonian), resolved to the base of the jawed vertebrate clade, with vertebrae comprising neural and haemal arches composed of perichondral bone. The placoderm synarcual preserves substantial developmental information from anterior (oldest) to posterior, where new vertebrae are incorporated. A subadult specimen of the pachyosteomorph arthrodire Dunkleosteus terrellli preserves vertebral elements showing varying degrees of anteroposterior fusion along the vertebral column. Synarcuals are rarely preserved in this group, and micro-CT scanning of this synarcual provides details of a transitional zone of vertebral fusion, providing unprecedented information on how each vertebrae is modified and incorporated into the synarcual. All elements in the synarcual retain vertebral identity, showing less fusion overall, more comparable to other arthrodires such as Compagopiscis. By comparison, synarcuals of other taxa such as ptyctodont placoderms, batoids, holocephalans (Chondrichthyes) and mammals (syncervical) show more complete fusion of vertebral elements.

The evolution of mammals from cynodonts is a key event in vertebrate history and is characterized by a number of modifications to the cranial skeleton. This is most prominently expressed in the emergence of a novel jaw joint and the reduction of the mandible to a single tooth-bearing bone in crown mammals. These skeletal changes are generally thought to be allied with increasing cranial strength in response to a more powerful and complex jaw musculature, and the evolution of a more ‘efficient’ feeding system. Using an integrated suite of digital reconstruction, visualization and biomechanical modelling techniques (FEA, MDA), we studied six key taxa (including Thrinxaodon, Probainognathus, Morganucodon, and Hadrocodium) across the cynodont-mammaliaform transition. This allowed testing the hypothesis that during feeding the cranial skeleton of cynodonts and mammaliaforms experienced progressively lower magnitudes of stress and strain and increased bite forces. Results show a slight decrease in average stress and strain across taxa, but do not support a large-scale trend for the increase of cranial strength towards crown mammals. However, we find that a reduction in size of the cranial system, as observed across the cynodont-mammaliaform transition, results in opposing trends of reducing bite forces, but also a substantial reduction of compressive and tensile stresses in the jaw joint. This suggests that presumed changes in the loading regime and/or the cranial morphology did not act as the main trigger for the emergence of a novel jaw joint. Rather, miniaturisation provided an evolutionary environment, in which substantial morphological modifications were possible.

A focus on cranial characters for determining relatedness is a predominant trait in many datasets, however this overemphasis can lead to distortion from sampler bias. We report on revised analyses of pachycormids - a key group within Actinopterygii, as part of the Holostei-Teleostei Transition, which display a phyletic trend towards reduced skeletal ossification with the increased adult size of a pachycormid taxon. This reduced preservation potential for the axial skeleton makes it difficult not to base phylogenetic assumptions primarily on the limited skull material present. However, pachycormids show a remarkable conservatism in their dermatocranial anatomy, the few differences being useful for showing the separation of genera, but of little utility in working out broader intrafamilial relationships. The combination of a paucity of postcranial characters in the Late Cretaceous pursuit predator Protosphyraena with a poor knowledge about the skulls of suspension-feeding pachycormids (SFPs) had led to the absence of Early Cretaceous predatory pachycormids being interpreted as indicating a ghost lineage between Protosphyraena and the European Upper Jurassic taxa Orthocormus and Hypsocormus over an almost 50 million year gap. However, the inclusion of several features from the pectoral and pelvic fins, supplemented by splanchnocranial characters, produces a much clearer picture that questions the traditional perception of a single carnivore lineage: Protosphyraena emerges as secondarily carnivorous from the SFPs’ tribe, mirroring 130 years of misidentification of North American Bonnerichthys specimens as Protosphyraena. Confirmation of this will rely on the further recovery of data concerning the skull morphology of SFPs.

Birds have evolved powerful forelimbs that are used primarily in flapping flight. This has rendered these appendages less useful for environmental manipulation than in many of their dinosaurian antecedents. Reliance on the head and neck for feeding and environmental interaction places high selective pressure on cervical form-function, potentially explaining the diversity in neck morphology seen in birds. However, to-date there has no been no systematic study of morphological diversity in the avian neck and its correlation with feeding habits. This study uses a combination of three-dimensional geometric morphometrics (GMM) and qualitative character coding to assess regionalisation within the cervical column of a wide variety of extant birds. These species represent a large diversity of feeding (carnivores, seed eaters) and functional (swimmers, flyers and terrestrial) ecology, cervical count (12-17) and body size. Results provide strong support for 5 cervical subregions (axis, anterior, middle, midposterior, posterior) in all species. The atlas subregion appears to show the strongest signal, with the axis (cervical 2) being clearly separate in all studied birds, possibly owing to its function into head stabilisation. Other subregions with a reasonably stable cervical count (anterior and posterior) also display a clear functional role. The remaining 2 regions (middle, midposterior) show much variability in cervical count between species (middle 2-6 cervicals, midposterior 1-4 cervicals). These results suggest that whilst the underlying Hox genetics may restrict avians to 5 cervical subregions, expansive variability in the middle and midposterior regions allow the cervical columns of birds to adapt to many different functional ecologies, and may be responsible for the large variety of neck morphologies observed in extant Aves.