The braincase and middle ear region underwent a dramatic reconfiguration during the fish–tetrapod transition, involving the loss of the intracranial joint and associated structures, as well as the loss of the lateral commissure and the transformation of the hyomandibula into a stapes. The earliest examples of the tetrapod condition are seen in Devonian stem tetrapods. Complete otoccipital regions have only been described from two genera, Ichthyostega and Acanthostega, which differ greatly from each other. Here we present the first complete otoccipital region of Ventastega, together with new data on Acanthostega that modify the published reconstruction. In lateral view, both braincases are similar in shape, with large fenestrae vestibuli and anteroposteriorly short, but tall, exoccipitals. However, in occipital view the exoccipital-basioccipital complex of Ventastega resembles that of Eusthenopteron and differs substantially from Acanthostega. Remarkably, both braincases contain an arcual plate, a sarcopterygian fish characteristic known in taxa with an intracranial joint, such as Eusthenopteron and Latimeria, but never before seen in a tetrapod. The hypophysial region of Acanthostega contains an interorbital foramen similar to that in post-Devonian tetrapods, contrasting with Ventastega which has a solid braincase wall with small foramina similar to the condition in Eusthenopteron. The suture pattern of the skull roof of Ventastega is fully resolved and the presence of an intertemporal bone is confirmed.

The fin-to-limb transition is heralded as one of the most important events in vertebrate evolution. Over the last few decades our understanding of how limbs evolved has significantly increased; but, hypotheses for why limbs evolved are still rather open. Fishes that engage their fins to ‘walk' along substrate may provide some perspective. The charismatic frogfishes are often considered to have the most limb-like fins, yet we still know little about their underlying structure. Here we reconstruct the pectoral fin musculoskeletal anatomy of the scarlet frogfish to identify adaptations that support fin-assisted walking behaviours. The data are compared to three additional anglerfish species: the oval batfish, which represents an independent acquisition of fin-assisted walking; and two pelagic deep-sea swimmers, the triplewart seadevil and ghostly seadevil. Our results clearly show broad musculoskeletal differences between the pectoral fins of swimming and walking anglerfish species. The frogfish and batfish have longer and more robust fins; larger, differentiated muscles; and better developed joints, including a reverse ball-and-socket glenoid joint and mobile ‘wrist'. Further, the frogfish and batfish show finer-scale musculoskeletal differences that align with their specific locomotor ecologies. Within, we discuss the functional significance of these anatomical features in relation to walking, the recurring evolution of similar adaptations in other substrate locomoting fishes, as well as the selective pressures that may underlie the evolution of limbs.

Specimens of trematopid amphibians from the Asturian (Upper Carboniferous) of Nýřany, Czech Republic, are redescribed as two taxa, namely Mordex calliprepes Steen and Mattauschia (gen. nov) laticeps Fritsch. Mordex calliprepes is represented by a single post-metamorphic specimen and has the diagnostic trematopid characters of the nasal region. Mattauschia laticeps is represented by one adult partial skull and mandible plus some fragments and two small post-metamorphic specimens including the species name-bearer. It has the trematopid-type modified lacrimal and a large but oval naris and appears to be the most primitive trematopid yet described. The stratigraphically sequential large trematopids Mattauschia, Fedexia, Ecolsonia and Acheloma show progressive acquisition of the derived features that characterise the terminal form Acheloma.

Mordex has a combination of primitive and derived characters and its position within the family is less clear. The many ‘branchiosaurs' in the Nýřany assemblage include specimens that could be larvae of both Mordex and Mattauschia but certain attribution is not possible and they are assigned to Olsoniformes incertae sedis. Mordex and Mattauschia appear to be terrestrial exotic elements in the Nýřany tetrapod assemblage, but with possible larvae in the lake assemblage. Representatives of at least four Palaeozoic dissorophoid families were present in late Middle Pennsylvanian/Asturian strata implying diversification of the Dissorophoidea prior to this time.

The early tetrapod Crassigyrinus scoticus was a large aquatic predator from the mid Carboniferous (late Viséan or early Serpukovian) of Scotland, around 330 My in age. There are five main specimens with cranial remains: an articulated skeleton; two incomplete skulls; and two lower jaws. Crassigyrinus retains several apparently primitive features of the palatal dentition and lower jaw, and its phylogenetic position is disputed. A partial lower jaw resembling that of Crassigyrinus was discovered at Burnmouth in the Borders region of Scotland. The horizon in which it was found is dated as late Tournaisian, CM palynozone, around 350 My in age. Though it lacks dentition, the jaw preserves much of the postsplenial, angular and surangular, whose appearance externally and internally is almost identical to that of C. scoticus. Internally, the jaw shows a similarly limited extent of the suturing between the splenial series and the prearticular, a primitive condition. Externally, the type and distribution of dermal ornamentation closely matches that of C. scoticus, as does the deeply excavated and marginally positioned lateral line groove. As well as external and internal features, all specimens of C. scoticus are of similar skull size, though the Burnmouth jaw is somewhat smaller. If correctly attributable to Crassigyrinus, this specimen extends the existence of the genus by approximately 20 million years towards the base of the Carboniferous.

A revised reconstruction of the dermal skull roof of Acanthostega gunnari from the Upper Devonian of East Greenland is provided, incorporating modifications consequent upon further study of the specimens and in the light of new information from the Upper Devonian genus Ventastega from Latvia. The new reconstruction features a midline gap between the frontal and nasal bones and median rostrals. A revised profile for the skull and a rendition of the dermal ornament is also provided.

A new reconstruction of the skull of Crassigyrinus scoticus (Lydekker) is provided, based on newly prepared material. A revised interpretation of the naris shows it in most respects to be like that of other Carboniferous tetrapods, lacking both an anterior tectal and a lateral rostral. However it does incorporate an enlarged septomaxilla, and part of the dorsal surface of the vomer is also visible within the naris of most specimens. Prominent paired buttresses run along the midline of the snout, and a single bowl-shaped interpremaxillary fenestra pierces the snout and palate but is not confluent with the naris or choana. A preopercular is probably absent. A new cladistic analysis places Crassigyrinus with the Viséan genus Whatcheeria, and puts those two taxa as a sister-clade to the anthracosaurs Proterogyrinus and Pholiderpeton. Temnospondyls form a clade with loxommatids, and these two arms form a dichotomy crownward to Greererpeton, Ichthyostega and Acanthostega which are successive stemward plesions.

Coprolites are most common in the transition zone between the East Kirkton Limestone and the Little Cliff Shale. One hundred and twenty five samples are classified in five groups on the basis of size and shape. Within these groups distinctive subgroups are described. Many of the coprolites are believed to have been produced by fish, but some could have been produced by eurypterids and aquatic tetrapods.