The late Viséan anthracosauroid Eldeceeon rolfei from the East Kirkton Limestone of Scotland is re-described. Information from two originally described and two newly identified specimens broadens our knowledge of this tetrapod. A detailed account of individual skull bones and a revision of key axial and appendicular features are provided, alongside the first complete reconstructions of the skull and lower jaw and a revised reconstruction of the postcranial skeleton. In comparison to Silvanerpeton, the only other anthracosauroid from East Kirkton, Eldeceeon is characterised by a proportionally wider semi-elliptical skull, comparatively smaller nostrils set farther apart, smaller and more rounded orbits, a shorter skull table with gently convex lateral margins, and a deeper suspensorium with a straight posterior margin and a small dorsal embayment. The remarkably large hind feet and elongate toes of Eldeceeon presumably represent an adaptation for attaining high locomotory speed through increased stride length and reduced stride frequency. This would necessitate great muscle force but few muscle contractions. At the beginning of a new stride cycle, repositioning the pes anteriorly and lifting the toes off the ground would require a strong and large muscle to pull the femur upward and rotate it inward and forward. It is hypothesised that such muscle might correspond to the puboischiofemoralis internus 2, which would extend along the posterior half of the vertebral column, consistent with the occurrence of long, curved ribs in the anterior half of the trunk. Using maximum parsimony and Bayesian inference, cladistic analyses of all major groups of stem amniotes retrieve a sister group relationship between Eldeceeon and Silvanerpeton, either as the most plesiomorphic stem amniote clade or as a clade immediately crownward of anthracosauroids.

The reconstructed palate of Whatcheeria deltae indicates a skull that was unusually narrow: at least 2.2 times longer than wide if the pterygoids are conservatively placed in the horizontal plane. This maximum width is narrower than any other early tetrapod reconstructed so far. Rotating the pterygoids to produce a vaulted palate would produce an even narrower skull. Primitive palatal features include very narrow interpterygoid vacuities and a vomer, palatine, and ectopterygoid with fang-sized replacement pairs. It is derived in that there is no anterior palatal fenestra and the premaxilla has a substantial palatal shelf – a combination of characters shared only with Proterogyrinus among early tetrapods. There is a possible septomaxilla in one specimen. Whatcheeria differs from and is more derived than Pederpes, its likely sister taxon, in that only the pterygoid is covered with denticles, the vomer, palatine, and ectopterygoid containing labyrinthine teeth only. Reconstructed dental occlusion indicates that the large choana apparently accommodated the large dentary fangs; this would be a unique feature among early tetrapods. The palatal ramus of the pterygoid is longer than the quadrate ramus, which does not have a descending flange. Like Meckel's cartilage in the lower jaw, the palatoquadrate is fully ossified in larger specimens, such that in a posterior view of the skull the pterygoid is mostly hidden from sight by the epipterygoid. The ossified neurocranium consists of the basiparasphenoid and basioccipital; no ossified sphenethmoid has been found. Remains of otic capsules are partial, crushed, and smeared, so no useful morphology is available. The stapes appears to be more columnar and less plate-like than in many other primitive, early tetrapods.

Open palates with large interpterygoid vacuities are a diagnostic characteristic of temnospondyl amphibians, the most species-rich group of early tetrapods. Aside from their functional roles, several other aspects of such vacuities, such as their variation and spatial relationships relative to the orbits, have received only scarce attention. The present work examines patterns of shape and size changes in the orbits and vacuities of temnospondyls using a time-calibrated phylogeny of 69 temnospondyl taxa and 13 additional early tetrapod ‘outgroups' (colosteids, an embolomere, ‘microsaurs' and nectrideans). Orbit and vacuity outlines are quantified in a comparative framework using standard eigenshape analyses. In addition, we employ a series of ratios of linear measurements of both orbits and vacuities, and subject them to a phylogenetic principal component analysis in order to evaluate their proportional changes relative to the skull and to one another. Finally, we examine rates of evolutionary change and their associated shifts for shape and size for both structures, and assess the strength and significance of the correlations between these two variables using phylogenetic generalised least squares analyses. Although orbits and vacuities have fairly simple outlines, they both reveal complex models of proportional change across the temnospondyl phylogeny. These changes exhibit strong phylogenetic signal, that is, trait covariance among taxa is predicted by tree topology. We discuss the hypothesis that, early in tetrapod evolution, the functional role of the vacuities was related to the accommodation of the anterior jaw muscles. Only later in evolution did such vacuities serve to accommodate the eye muscles only.

The skull of the extinct rhinoceros Stephanorhinus kirchbergensis (Jäger, 1839) was discovered in the Chondon River valley (Arctic Yakutia, Russia) during the summer of 2014. This is the first find of Stephanorhinus above the Arctic Circle, expanding significantly the known geographic range of the genus. 14C dating and geologic evidence indicate that the skull dates to between 48,000 and 70,000 yr, corresponding to Marine Oxygen Isotope Stage 4/3. It is thus among the latest records of this species. To explore the evolutionary and natural history of this relatively unknown animal, we performed morphological, dietary, and genetic analyses. Phylogenetic inference based on a complete mitochondrial genome sequence confirms the systematic placement of Stephanorhinus as most closely related to the extinct woolly rhinoceros, Coelodonta. Food remains in the fossas of the cheek teeth, identified as Larix, Vaccinium, Betula sp., Aulacomnium, and dicotyledonous herbs and grasses, suggest a mixed feeder’s diet. Microwear analysis suggests that, during the last months of its life, this individual fed predominantly on leaves and twigs. The habitat of Stephanorhinus comprised grassland and open woodland that were characterized by moist and cold climate conditions, similar to those in the region today.

Age is one of the most important life history parameters required to understand the dynamics of mammalian populations. Growth Layers Groups (GLGs) are incremental units of calcified tissue in the teeth (dentine and cementum), which represent a pattern of cyclical deposition that can be counted. However, the estimation of absolute age in GLGs demands a skull with teeth, the permission to destroy part of a tooth, equipment to cut the teeth, and experienced GLGs readers. In 1954 Sivertsen proposed an alternative method using cranial suture age (CSA) to establish age categories. However, there are no studies validating the CSA in relation to GLGs. Thus, this study examined whether there is a correlation between age categories proposed by the CSA and chronological age in years from GLGs of South American fur seals (Arctocephalus australis) (N = 52) and of South American sea lions (Otaria flavescens) (N = 37). 93% of the skulls of A. australis and 83.8% of O. flavescens corresponded accurately to the age in years estimated by each cranial suture age range. These results indicated the existence of high correspondence between the CSA and the GLGs age (r: 0.491 for A. australis and r: 0.675 for O. flavescens). However, an adaptation to Sivertsen's method is recommended: using only eight sutures (excluding the premaxillary-maxillary suture for CSA analysis, due to its late fusion), and updating the intervals for cranial sutures, that correspond to 16–32 = adults, 11–15 = young and 8–10 = pups.

Four species of Ophisaurus, O. fejfari, O. spinari, O. robustus and O. holeci, are recognized on the basis of parietals from the Early Miocene of the Czech Republic and Germany. The fifth species, O. acuminatus, is described from the Late Miocene of Germany, but its parietal is not preserved. This paper describes new O. fejfari, O. spinari, O. robustus and O. holeci specimens from the Early and Middle Miocene of the Czech Republic and Germany. The O. fejfari and O. holeci parietals from Germany are the first records of these species outside the Czech Republic. This paper provides a significant contribution to the understanding of both interspecific and intraspecific Ophisaurus variability in the Cenozoic of Europe. A well-preserved parietal of Anguis rarus sp. nov. is described from the Early Miocene of Germany. This is the first record of the parietal of Anguis in the Cenozoic. A new parietal from the Middle Miocene of Germany is described as Pseudopus sp. It differs from the contemporaneous P. laurillardi only in the absence of the large and distinctly laterally projecting anterolateral processes of the parietal. In the Miocene, Ophisaurus and Pseudopus exhibit a higher diversity than that of the preceding geological periods of the Cenozoic. Besides, Ophisaurus emigrates from Europe to (1) Asia and via the Bering Strait to North America, and (2) North Africa during the Oligocene and Miocene. By contrast, Anguis and Pseudopus are limited to Eurasia. The palaeobiogeography of members of Anguinae is discussed.

Reconstructed soft-tissues of the craniocervical region of dyrosaurids are analysed under functional aspects to determine their prey-catching capabilities. Jaw adductors and jaw abductors are enlarged and possess longer muscle fibres that are increased by a long retroarticular process. This muscle enlargement resulted in a more forceful and quicker contraction, effective for movement of the long rostrum. The occipital joint and the cervical ribs, the long retroarticular process and the high cervical neural spines of dyrosaurids suggest a higher dorsoventral flexibility of the craniocervical region, whereas lateromedial flexibility was reduced. The epaxial muscles of the neck and scapular muscles were enlarged, and the supraspinal ligament most likely fanned out into a nuchal ligament. Suspension of the neck and skull of dyrosaurids was achieved by the scapular muscles, dorsal neck ligaments and epaxial muscles, whereas ventral bracing was reduced. From the reconstructed specializations of the feeding apparatus, an enhanced capability for movements in the vertical plane is postulated for dyrosaurids, together with reduced lateral movements of the craniocervical region. Besides laterally directed strokes for fish-catching, behaviours such as poking in the substrate, bottom feeding, multidirectional prey-catching strokes and improvement of diving skills were options for dyrosaurids and suggest a possible expansion of their diet. The longirostrine skull limited prey size, but the dentition allowed shelly prey items. The specialization of the food-capturing system in dyrosaurids and the resulting expansion of their food spectrum is one possible explanation for their evolutionary success, including their undisturbed transition of the Cretaceous–Palaeogene boundary.

The harbour porpoise is seriously depleted and threatened with extinction in the Baltic Sea. It is usually assumed that Baltic porpoises form a separate population unit, although the evidence for this has been disputed lately. Here, a 3-D geometric morphometric approach was employed to test a number of hypotheses regarding population structure of the harbour porpoise in the Baltic region. 277 porpoise skulls from Denmark, Sweden, Finland, Germany and Poland were measured with a suite of 3-D landmarks. Statistical analyses revealed highly significant shape differences between porpoises from the North Sea, Belt Sea and the inner Baltic Sea. A comparison of the directionalities of the shape vectors between these units found differences that cannot be attributed to a general, continual shape trend going from the North Sea to the inner Baltic Sea. These vectors indicate a morphological adaptation to the specific sub-areas. Such adaptation may be the result of the topographic peculiarities of the area with variable topography and shallow waters, e.g. in the Belt Sea porpoises, there may be a greater reliance on benthic and demersal prey. The present results show that isolation by distance alone is an unlikely explanation for the differences found within the Baltic region and thus support previously reported molecular indications of a separate population within the inner Baltic Sea.

Beaked whales are not a commonly encountered species, but Cuvier's beaked whale, Ziphiuscavirostris, is the most cosmopolitan. Nonetheless, little is known of its distribution in the north-eastern Indian Ocean, particularly along the coasts of India, Pakistan and Iran. Here we present the first confirmed record of the species for Pakistan from a stranded specimen that was found during a routine beach survey. None have been seen during inshore boat surveys to date. Considering the level of naval activity and seismic surveys in the waters off Pakistan, incorporation of mitigating measures and monitoring surveys are suggested to avoid potential beaked whale mortality. This is the first confirmed record of Z. cavirostris on the Pakistani coast and is an important finding for the Pakistan Biodiversity Action Plan and their National Conservation Strategy for marine mammals.

Previously described and new specimens of the anthracosaur Silvanerpeton miripedes from the Scottish Viséan of East Kirkton yield important new data which allow us to provide a more complete reconstruction of the skull roof, palate, braincase and lower jaw. A stout sacral rib and an incompletely ossified tarsus with a subquadrangular intermedium are also recorded for the first time. A remarkably well preserved humerus in extensor view shows similarities with humeri of immature specimens of the embolomere Proterogyrinus. A new cladistic analysis, built from combining characters used in two recent matrices, places Silvanerpeton in a basal position relative to embolomeres and more derived stem amniotes. Data from Silvanerpeton inform character polarity near the base of the amniote total group. We discuss some morphofunctional implications of character changes at the root of total group amniotes, acquisition of terrestrial habits, and patterns of early disparity in this clade.