Pliosaurids were a long-lived and cosmopolitan group of marine predators that spanned 110 million years and occupied the upper tiers of marine ecosystems from the Middle Jurassic until the early Late Cretaceous. A well-preserved giant pliosaurid skull from the Late Jurassic Kimmeridge Clay Formation of Dorset, United Kingdom, represents a new species, Pliosaurus kevani. This specimen is described in detail, and the taxonomy and systematics of Late Jurassic pliosaurids is revised. We name two additional new species, Pliosaurus carpenteri and Pliosaurus westburyensis, based on previously described relatively complete, well-preserved remains. Most or all Late Jurassic pliosaurids represent a globally distributed monophyletic group (the genus Pliosaurus, excluding ‘Pliosaurus’ andrewsi). Despite its high species diversity, and geographically widespread, temporally extensive occurrence, Pliosaurus shows relatively less morphological and ecological variation than is seen in earlier, multi-genus pliosaurid assemblages such as that of the Middle Jurassic Oxford Clay Formation. It also shows less ecological variation than the pliosaurid-like Cretaceous clade Polycotylidae. Species of Pliosaurus had robust skulls, large body sizes (with skull lengths of 1.7–2.1 metres), and trihedral or subtrihedral teeth suggesting macropredaceous habits. Our data support a trend of decreasing length of the mandibular symphysis through Late Jurassic time, as previously suggested. This may be correlated with increasing adaptation to feeding on large prey. Maximum body size of pliosaurids increased from their first appearance in the Early Jurassic until the Early Cretaceous (skull lengths up to 2360 mm). However, some reduction occurred before their final extinction in the early Late Cretaceous (skull lengths up to 1750 mm).

Prion diseases, or transmissible spongiform encephalopathies, are neurodegenerative diseases that can only be accurately diagnosed by analysis of central nervous system tissue for the presence of an abnormal isoform of the prion protein known as PrP(Sc). Furthermore, these diseases have long incubation periods during which there are no clear symptoms but where the infectious agent could still be present in the tissues. Therefore, the development of diagnostic assays to detect a surrogate marker for the presence of prion disease is essential. Previous studies on mice experimentally infected with scrapie, an ovine spongiform encephalopathy, suggested that changes in the levels of Mn occur in the blood and brain before the onset of symptoms of the disease. To assess whether these findings have relevance to the animal diseases scrapie and bovine spongiform encephalopathy, tissues from bovine spongiform encephalopathy- and scrapie-infected cattle and sheep were analyzed for their metal content and compared with values for noninfected animals. In field cases and experimentally infected animals, elevated Mn was associated with prion infection. Although some central nervous system regions showed elevated Mn, other regions did not. The most consistent finding was an elevation of Mn in blood. This change was present in experimentally infected animals before the onset of symptoms. In scrapie-infected sheep, elevated Mn levels occurred regardless of the genotype of the sheep and were even detected in scrapie-resistant sheep in which no symptoms of disease were detected. These findings suggest that elevated blood Mn could be a potential diagnostic marker for prion infection even in the absence of apparent clinical disease.

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Complete skulls of giant marine reptiles of the Late Jurassic are rare, and so the discovery of the 1.8-mlong skull of a pliosaur from the Kimmeridge Clay Formation (Kimmeridgian) of Westbury, Wiltshire, UK, is an important find. The specimen shows most of the cranial and mandibular anatomy, as well as a series of pathological conditions. It was previously referred to Pliosaurus brachyspondylus, but it can be referred reliably only to the genus Pliosaurus, because species within the genus are currently in need of review. The new specimen, together with another from the same locality, also referred to P. brachyspondylus, will be crucial in that systematic revision, and it is likely that the genus Pliosaurus will be found to include several genera. The two Westbury Pliosaurus specimens share many features, including the form of the teeth, but marked differences in the snout and parietal crest suggest sexual dimorphism; the present specimen is probably female. The large size of the animal, the extent of sutural fusion and the pathologies suggest this is an ageing individual. An erosive arthrotic condition of the articular glenoids led to prolonged jaw misalignment, generating a suite of associated bone and dental pathologies. Further damage to the jaw joint may have been the cause of death.

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Mannitol, an acyclic six-carbon polyol, is one of the most abundant sugar alcohols occurring in nature. In the button mushroom, Agaricus bisporus, it is synthesized from fructose by the enzyme mannitol 2-dehydrogenase (MtDH; EC 1.1.1.138) using NADPH as a cofactor. Mannitol serves as the main storage carbon (up to 50% of the fruit body dry weight) and plays a critical role in growth, fruit body development, osmoregulation, and salt tolerance. Furthermore, mannitol dehydrogenases are being evaluated for commercial mannitol production as alternatives to the less efficient chemical reduction of fructose. Given the importance of mannitol metabolism and mannitol dehydrogenases, MtDH was cloned into the pET28 expression system and overexpressed in Escherichia coli. Kinetic and physicochemical properties of the recombinant enzyme are indistinguishable from the natural enzyme. The crystal structure of its binary complex with NADP was solved at 1.5-Å resolution and refined to an R value of 19.3%. It shows MtDH to be a tetramer and a member of the short chain dehydrogenase/reductase family of enzymes. The catalytic residues forming the so-called catalytic triad can be assigned to Ser

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Dental morphology and patterns of tooth replacement in representatives of the clade Pliosauridae (Reptilia, Sauropterygia) are evaluated in detail. The jaws of one basal (Thalassiodracon hawkinsii) and two derived species (Pliosaurus carpenteri, Pliosaurus kevani) were visualized by μCT scans, and the ontogenetic patterns, or ‘movement paths’, of replacement teeth could be mapped. Other specimens (Peloneustes philarchus and Pliosaurus westbuyensis) with well-preserved jaws containing functional and replacement teeth in situ were also examined directly, and waves of tooth replacement could be inferred from the degree of in situ tooth development and the fusion between functional and replacement alveoli. The analysis revealed symmetrical tooth eruption over the medial axis throughout the length of the jaw in the basal pliosaurid Thalassiodracon. By contrast, symmetrical tooth eruption patterns occur only along the anterior sections of the jaws of derived pliosaurids. In Pliosaurus, replacement schedules differ in the anterior and posterior portions of the jaws and appear to correlate with differences in tooth morphology and symmetrical replacement. The anterior teeth exhibit longer replacement cycle periods and symmetrical replacement, while shorter cycle periods and asymmetry are seen posteriorly. A longer period suggests slower replacement and is characteristic of large, specialized caniniform teeth in the longer snouted Late Jurassic taxa. Smaller posterior teeth have a shorter period and therefore a faster replacement cycle. The transition from long to short replacement period over the length of the jaw is thought to account for the loss of symmetry. This differentiation could relate to differential tooth function and a type of heterodonty. We therefore propose a new model of pliosaurid tooth replacement patterns and present it in a phylogenetic context.