Tristychius arcuatus, from the late Viséan of Scotland, is known from numerous ironstone nodule-encased specimens. These are reinvestigated using computerised tomography (CT) scanning and 3-D digital reconstruction methods. CT scans of the neurocranium (braincase) corroborate many features of the existing reconstruction, but also reveal new details of the gross proportions, the external morphology and, for the first time, features of the internal morphology, including the otic skeletal labyrinth. The unusual position of the articulation for the palatoquadrate on the ventral surface of the postorbital process is confirmed, but the area for the hyoid articulation is relocated posteriorly and the configuration of nerve foramina within the orbit is changed. A preliminary phylogenetic hypothesis is offered, suggesting a place for Tristychius within a sequence of early branching events in the elasmobranch lineage. In this, Tristychius is not resolved as a hybodontid, but is instead a stem elasmobranch possibly related to genera such as Acronemus, and exemplifying anatomical conditions close to the base of the Euselachii. As such, the neurocranium of Tristychius offers important insight into a defining feature of these early members of the anatomically advanced elasmobranchs: the origin of specialised phonoreception.

The oldest records on the sharks of the Sea of Marmara are limited to a few notes on two great white sharks, Carcharodon carcharias, which were caught in the southern part of the Bosphorus Strait by the bluefin tuna (Thunnus thynnus) handliners in February and November of 1881 (Fergusson, 1996: Appendix 3, 345). A review of the shark-specific or general ichthyology studies of the Sea of Marmara, as well as of the daily newspapers published since the beginning of 1900s, providing information on the capture of sharks in Marmaric waters, revealed the historical and contemporary occurrence of 21 shark species in the Sea of Marmara. The contemporary occurrence of 13 of the 21 species in the Sea of Marmara has been confirmed by recent studies and fishery records. Recent studies showed that the fish fauna of the Sea of Marmara comprises 235 species, 13 of which are shark species, with the confirmed contemporary occurrences of sharks representing 5.53% of the total ichthyofauna.

The cookiecutter shark, Isistius brasiliensis, is confirmed for the first time from the eastern North Pacific Ocean. The shark, a female 432 mm in total length, was caught in a sablefish pot at a depth of 1132 m off San Nicolas Island, California, USA (32°59′05″N 120°25′99″W).

The velvet dogfish, Zameus squamulosus, is a poorly known deep water shark, known from the Atlantic, Indian, western, central and south-eastern Pacific Oceans. In this paper, the first record of the velvet dogfish, caught from the eastern North Pacific is reported. The shark, a male 533 mm in total length, was caught by bottom trawl at a depth of 770.7 m off Long Beach, California (33°43′15″N 118°32′14″W), USA.

Non-marine Bathonian (Middle Jurassic) strata on the Isles of Eigg and Skye in Scotland have yielded fossil remains of eight hybodont shark taxa. Faunas from several horizons within the Lealt Shale and Valtos Formation on the Isle of Eigg include six species: Hybodus grossiconus, Hybodus sp. 1, Hybodus sp. 2, Lissodus leiodus, L. leiopleurus and Parvodus pattersoni. Large collections of teeth of L. leiodus and L. leiopleurus enable a better understanding of the dentitional patterns of the two species and their differential diagnosis. Surface-collecting from exposures of the Kilmalaug Formation on the Isle of Skye yielded hybodont teeth of two taxa: Hybodus sp. 3 and Acrodus caledonicus sp. nov. The occurrence of Acrodus in the Bathonian of Scotland is one of the youngest known occurrences of this genus, and the only non-marine record in the European Jurassic. Collectively, the hybodont assemblages from the Scottish Bathonian provide evidence that non-marine faunas of the group were specifically diverse in the Middle Jurassic.

A proximal fragment of a gill raker identified as belonging to a shark of the genus Cetorhinus was collected from middle Eocene deposits of the La Meseta Formation in the northern part of Seymour Island, Antarctica. This is the first record of a fossil basking shark from Antarctica and one of the earliest records of the genus. The minimum age of Cetorhinidae is middle Eocene. The only living species of the family Cetorhinidae is a very large plankton feeder, Cetorhinus maximus. Basking sharks are unknown in subantarctic or Antarctic waters but occur on both South American coasts today. The evolution of filter-feeding vertebrates is discussed.

A section of the Vitabäck Clays at Eriksdal in southern Sweden was sampled for vertebrate fossils. Large bulk samples were collected from three horizons, including two coquina beds, VC3 and VC11, and a silty clay bed, VC7. Shark teeth are very common and constitute the main portion of the vertebrate material discussed herein. The selachian tooth faunas are almost exclusively represented by hybodonts, although a single tooth from a neoselachian shark, Squatinidae indet., was recorded from one horizon (VC3). Hybodont species identified from the Vitabäck Clay samples include Egertonodus basanus, Hybodus parvidens and Parvodus rugianus. Hybodont remains, other than teeth, include five morphotypes of placoid scales, incomplete cephalic spines and fragmentary fin spines.

Other fossil groups represented in the sieved residues from the bulk samples include bivalves, gastropods and bony fish. Together with the selachians, they indicate fluctuating palaeosalinities in the area. The lower coquina bed, VC3, includes taxa indicating mesohaline conditions while the composition of the fauna in the other coquina bed, VC11, suggests oligohaline settings. In bed VC7, the presence of amphibian remains and the rarity of selachian fossils indicate an even lower salinity. Palynomorphs from the basal part of the section, immediately below bed VC3, indicate an earliest Cretaceous (Berriasian) age.

A new fossil elasmobranch from the Lower Carboniferous Oil Shale groups (Viséan) of the Edinburgh area shows a mosaic of characters typical of at least two groups of early sharks. Its most distinctive feature is the small bicuspid teeth of “Diplodus” type. This, together with the long dorsal fin and the structure of the single, shallowly inserted dorsal spine, form a suite of characters previously considered unique to late Palaeozoic xenacanth sharks. Other features, such as the large equilobate tail and the structure of the pectoral fins, may have been retained from an ancestor of a more typical Palaeozoic elasmobranch appearance found in anacanthous and ctenacanth sharks. It is suggested that the xenacanths evolved from an ancestor within the anacanth-ctenacanth assemblage early in Carboniferous times and became adapted to a freshwater environment. This ancestor probably possessed a complex dermal skeleton including growing scales with both thickened and thin concave bases.

The fauna of the fish-bearing nodules amongst which this shark has been found is interpretedas being lagoonal in origin. The shark was probably a medium sized (c. 0·75–2·0 m lng)predator inhabiting the surface waters of the lagoon.