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The famous Rhaetian bone bed (Late Triassic, 205 Ma) is well known because it marks a major switch in depositional environment from terrestrial red beds to fully marine conditions throughout the UK and much of Europe. The bone bed is generally cemented and less than 10 cm thick. However, we report here an unusual case from Saltford, near Bath, S.W. England where the bone bed is unconsolidated and up to nearly 1 m thick. The exposure of the basal beds of the Westbury Formation, Penarth Group includes a bone bed containing a diverse Rhaetian marine microvertebrate fauna dominated by sharks, actinopterygian fishes and reptiles. Despite the unusual sedimentary character of the bone bed, we find similar proportions of taxa as in other basal Rhaetian bone beds (55–59 % Lissodus teeth, 13–16 % Rhomphaiodon teeth, 12–14 % Severnichthys teeth, 6–9% Gyrolepis teeth, 3–4% undetermined sharks’ teeth, 1–3% undetermined bony fish teeth, and

Two sites in the Villany Hills, Hungary, have yielded rich fish assemblages from Middle to Late Triassic shallow marine deposits. The collected material comes from the Ladinian Templomhegy Dolomite Member and from the Carnian Meszhegy Sandstone Formation. The ichthyofauna is composed of both chondrichthyans (Hybodontidae indet., Palaeobates angustissimus, ‘Polyacrodus’ sp., ?Lissodus sp.) and osteichthyans (Gyrolepis sp., Birgeria sp., and further indeterminate actinopterygians). Despite the large sample size, no remains of neoselachians have been found. The Ladinian Templomhegy Dolomite is dominated by durophagous hybodontiforms (Palaeobates angustissimus, ?Lissodus sp.), but the piscivorous hybodontid and the generalist ‘Polyacrodus’ sp. are missing, while in the fish fauna collected from the Carnian Meszhegy Formation indeterminate piscivorous hybodontids are the most common elements and durophagous forms are much less abundant. The dominance of piscivorous hybodontids in the Carnian Meszhegy Sandstone could be related to the global decrease of diversity of marine fish-eating reptiles (e.g., nothosaurs) or to a change of paleoenvironmental conditions. The present study improves our knowledge on the poorly known Triassic vertebrate faunas of the Tisza Mega-unit, which formed a segment of the passive Neotethys margin of the European Plate and shows an important example of a potential vertebrate faunal shift during the Middle to Late Triassic.

Fossil remains of fishes found in Rhaetian (Late Triassic, c.208.5–201.3 Ma) sediments collected from a subrosion pipe in the Winterswijk quarry are described. The fauna shows great similarity to material known from the British Triassic of the Penarth Group and from other localities in Northwestern Europe. Both chondrichthyan and osteichthyan teeth and scales are present. Most abundant are the sharks Lissodus minimus and Rhomphaiodon minor and the actinopterygians Gyrolepis albertii, Saurichthys longidens and Birgeria acuminata. Isolated teeth of the latter two taxa were known under the name Severnichthys acuminatus, but the genus Severnichthys is here considered a nomen dubium; it should be suppressed in order to make the taxonomy less complicated.

Rhaetian bone beds have been described from many locations in south-west England, around Bristol. One site that has never been reported is Stowey Quarry, some 13 km south of Bristol. This quarry yielded Lias, and revealed thin Rhaetian units in the quarry floor, including two bone beds, the basal Rhaetian bone bed, and a second, higher bone bed, also within the Westbury Formation. The fossil fauna of both includes elements typical of Rhaetian bone beds elsewhere, but showing differences in faunal composition between the two. The basal bone bed yielded more specimens and more species, with three taxa (Sargodon tomicus, Rhomphaiodon minor and Hybodus cloacinus) exclusive to this bed and eleven identified in total. Severnichthys acuminatus accounts for more than 50% of the countable teeth from the basal bone bed, followed by Gyrolepis albertii with 20%, Lissodus minimus with 14% and Rhomphaiodon minor with 9%. The basal bone bed, as ever, is dominated by chondrichthyans, whereas the upper bone bed is dominated by osteichthyans, which form 90% of the non-dental remains. The only unique taxon is Dapedium, and Gyrolepis albertii is the most abundant species with 45% of countable teeth, followed by Severnichthys acuminatus with 38% and Duffinselache holwellensis with 11%. These faunal differences, and the equally good condition of specimens between both samples confirms that the upper bone bed is independent of the basal bone bed, and is not a reworked subsample.

A new lonchidiid genus,Pristrisodus, from the Upper Triassic Tiki Formation of India is described based on multiple, well-preserved, isolated teeth. Comparative analysis resulted in synonymizingParvodus tikiensisandLissodus duffini,which are known from the same horizon and resulted in a new taxon,Pristrisodus tikiensisn. comb. These teeth are elongated with mesiodistal length greater than or equal to twice the labiolingual width and have a high principal cusp, lateral cusplets, a distinct ridge near the crown-root junction labially and higher up on the crown lingually, weak ornamentation, and linear depression along the crown-root junction. Five morphotypes based on overall shape, robustness and crown height are determined. The teeth show a gradual monognathic heterodonty. The anterolateral teeth (morphotypes I−II) have high, pyramidal principal cusp with two or three small but pointed cusplets, and triangular labial and lingual protuberance. The posterolateral teeth (morphotypes III−IV) have four incipient cusplets, relatively low principal cusp, bilobed/rounded, hanging labial and incipient lingual protuberances. Morphotype V comprises anterior teeth that are broad, triangular and robust, and have rounded/blunt principal cusp, one cusplet, and low, hanging labial peg. Multivariate analyses corroborate the qualitative assessment of the Indian hybodonts. Dental histology ofPristrisodusn. gen., shows that it is distinctly different from other lonchidiid genera. The assemblage of freshwater sharks, along with other vertebrate microfossils of the Tiki Formation, shows similarity with that of the lower Tecovas Formation of the Chinle Group, USA. The euryhaline nature resulted in the adaptation of the hybodonts to freshwater systems in India during the Carnian.

Microvertebrates are common in the basal bone bed of the Westbury Formation of England, documenting a fauna dominated by fishes that existed at the time of the Rhaetian Transgression, some 206 Myr ago. Two sites near Chipping Sodbury, south Gloucestershire, Barnhill Quarry and Chipping Sodbury railway cutting, show differing faunas. Top predators are the large bony fish Severnichthys and the shark Hybodus cloacinus, which preyed on smaller sharks such as Lissodus and Rhomphaiodon. These fishes in turn may have fed on a mixed diet of other fishes and invertebrates, and Lissodus was a shell crusher. Comparisons of these faunas with others described recently from the Bristol region, and from Devon, indicate remarkable faunal similarities in the Rhaetian basal Westbury Formation bone bed over a wide area, based on a variety of ecological statistics that document species diversities and relative abundances. Only the fauna from the Chipping Sodbury railway cutting differs significantly.

A diverse microvertebrate fauna is described from the Virgin Hills and Napier formations, Bugle Gap Limestone Canning Basin, Western Australia. Measured sections at Horse Spring and Casey Falls (Virgin Hills Formation) and South Oscar Range (Napier Formation) comprise proximal to distal slope carbonates ranging in age from the Late Devonian Frasnian to middle Famennian. A total of 18 chondrichthyan taxa are identified based on teeth, including the first record of Thrinacodus tranquillus, Cladoides wildungensis, Protacrodus serra and Lissodus lusavorichi from the Canning Basin. A new species, Diademodus dominicus sp. nov. is also described and provides the first record of this genus outside of Laurussia. In addition, the upper range of Australolepis seddoni has been extended to Late Devonian conodont Zone 11, making it the youngest known occurrence for this species. The Virgin Hills and Napier formations microvertebrate faunas show close affinities to faunas recovered from other areas of Gondwana, including eastern Australia, Iran, Morocco and South China, which is consistent with known conodont and trilobite faunas of the same age.

Purpose In the present study, we described, for first time, the chondrichthyan fauna from several Middle-Late Triassic sections in the Betic Domain and compare it with other recent described coeval faunas from the Iberian Ranges. Methods Specimens were retrieved after the dissolution (with 10% acetic acid) of carbonate rocks. Results The assemblage comprises of seven species belonging to six genera (Hybodus plicatilis, Omanoselache bucheri comb. nov., Omanoselache contrarius comb. nov., Lonchidion derenzii, Lissodus aff. L. lepagei, Pseudodalatias henarejensis and cf. Rhomaleodus budurovi), most of them non-nesoselachian. Chondrichthyans remains occur in levels dating from Ladinian to Carnian according with bivalves, ammonoids and conodonts. Conclusions The findings are comparable, in taxonomical terms, to the chondrichthyan fauna from the Ladinian of the Iberian Range that was recently described, although chondrichthyans seems noticeably less abundant in the Betic Domain. Most of the species found occur also in the Iberian Range, with the exception of Lonchidion derenzii and cf Rhomaleodus budurovi, which occur in the Boyar Section, dated as Carnian. The small size of all teeth recovered, belonging probably to young specimens, suggest that the very shallow epicontinental environments recorded in Middle-Upper Triassic rocks from the Betic Domain could be used as nursery areas.

Chondrichthyan fish remains reported from the Permian (Kazanian) deposits of the Chiosha Bay, and the lower course of the Nadtey River of the Kanin Peninsula (Nenets Autonomous District, Arkhangelsk Region, Russia) include dental elements and scales belonging to Stethacanthus cf. S. altonensis (St. John et Worthen, 1875), Symmoriiformes gen. indet., “Ctenacanthus” sp. and “Lissodus” sp., Euselachii gen. indet., Adamantina benedictae Bendix-Almgreen, 1993 and Kanodus robustus sp. nov. The latter genus is assigned to the previously monotypic family Psephodontidae. The record of Stethacanthus in the Middle Permian of Russia is its youngest occurrence worldwide, whilst the occurrence of Adamantina benedictae in the Middle Permian of the Kanin Peninsula is older than the Greenland record.

Here we present for the first time a detailed taxonomic study of a diverse chondrichthyan fauna from the Middle Triassic of the Iberian Range (Spain). The assemblage consists of isolated remains of seven species of five non-neoselachian shark genera (Palaeobates, Hybodus, Pseudodalatias, Prolatodon, gen. nov., and Lissodus), including a new species of hybodontiform shark, Hybodus bugarensis, sp. nov. In addition, a new homalodontid genus, Prolatodon, sp. nov., is erected for the taxa ‘Polyacrodus’ bucheri and ‘Polyacrodus’ contrarius. The chondrichthyans of the Iberian Range represent a heterogeneous group from a paleogeographic point of view made up of common components of Middle Triassic shark faunas of northern Europe (Hybodus plicatilis and Palaeobates angustisimus) together with species only known previously from North America and China (Prolatodon bucheri, comb. nov., and Prolatodon contrarius, comb. nov.), as well as several ‘endemic’ taxa (Pseudodalatias henarejensis, Hybodus bugarensis, ...

article i nfo Fossil shark remains occur in both marine and nonmarine Late Palaeozoic deposits, therefore their palaeo- ecology is controversial. The oxygen and strontium isotopic composition of biogenic fluorapatite in 179 teeth, scales and spines predominantly of hybodontid (Lissodus) and xenacanthiform (Orthacanthus, Xenacanthus, Bohemiacanthus, Triodus) sharks from various Late Carboniferous (Moscovian) to Early Permian (Artinskian) basins of Europe are used as ecological tracers to decipher diadromous or obligate freshwater lifestyle of the investigated taxa. The δ 18 OP values of the different shark teeth range from 11.7 to 20.2‰ within the different basins with mean values of 16.9±0.5‰ for the Bohemian Massif, 16.2±0.8‰ for eastern Germany, 18.2±1.0‰ for southwestern Germany, 18.5±0.7‰ for southern-central Spain, 17.6±0.4‰ for

The oxygen and strontium isotopic composition of 125 teeth of the hybodont sharks Lissodus and Hybodus from various late Triassic (Rhaetian) bone bed localities in the Central European Basin are used as environmental and ecological tracers for the shallow epicontinental Rhaetian Sea. The preservation of tooth enameloid was ascertained by cathodoluminescence microscopy. Mean δ18OP values differ regionally across the Rhaetian Sea with values of 18.6 ± 0.6‰ near the western gate, 16.1 ± 0.8‰ in the east, 15.4 ± 0.6‰ in the southeast, and 17.7 ± 0.9‰ in the south. The δ18OP values in the eastern Rhaetian Sea are 4–5‰ lower relative to Tethyan seawater, while teeth from the southern and western parts close to the marine gates are less fractionated. The strontium isotopic composition of teeth from most localities is more radiogenic in comparison to late Triassic seawater. The observed spatial δ18OP trend in the Rhaetian Sea indicates a shift from marine to brackish conditions in the south and west towards extensively brackish conditions with salinities of less than 16‰ in the east, thus confirming the existence of two marine gates. Brackish conditions persisted throughout early Rhaetian times, and were maintained by increased fluvial discharge from the Vindelician–Bohemian and Fennoscandian Highs as a result of enhanced atmospheric moisture availability in the course of the Rhaetian transgression. The δ18OP values of Lissodus and Hybodus indicate euryhaline behaviour of Rhaetian hybodonts by exceeding modern shark intraspecific variability. The lack of accordance in δ18OP values between different isotopically conspicuous localities in the Rhaetian Sea contradicts a basin-wide migration pattern. Differences between co-site taxa might indicate some degree of niche partitioning.

Numerous isolated teeth, fin spine fragments and dermal denticles of a hybodont shark from a lacustrine limestone horizon at the top of lithofacies B of the Late Carboniferous to Early Permian succession of the Guardia Pisano Basin (Sulcis area, southwestern Sardinia, Italy) are assigned to a new species of the genus Lissodus Brough, 1935. Lissodus sardiniensis sp. nov. is erected on the basis of about 500 teeth, which show a unique feature of only one pair of lateral cusps that are bent in the direction of the prominent central cusp. Weak heterodonty allows distinction of symphyseal, mesial to anterolateral, and lateral teeth. Lissodus sardiniensis sp. nov. was a freshwater-adapted durophagous shark of bottom dwelling habit, an interpretation supported by general construction of the dentition and the morphology of the dermal denticles. The association with Acanthodes, diplodoselachid sharks and branchiosaurs allows the reconstruction of a five-level trophic chain for the Guardia Pisano Basin. The discove...

Hybodont remains from the Early Cretaceous of the Basque-Cantabrian Basin (Cantabric Range) in the North of Spain are described for the first time. This assemblage represents a highly diversified shark fauna adapted to different feeding habits. Isolated remains of six hybodont genera, namely Hybodus, Egertonodus, Planohybodus, Lonchidion, Parvodus, and Lissodus, have been recovered and described from the freshwater Vega de Pas Formation in the locality of Vega de Pas (Cantabria, Northern Spain). Most of these taxa are known from the English Wealden, making the shark fauna of the Vega de Pas 1 site the most similar assemblage to English Wealden shark fauna among any other site known in Europe.

Manor Farm Quarry shows a detailed record of the entire Rhaetian section typical of southwest England. It has yielded a standard Rhaetian marine fauna, including eight species of sharks, four species of actinopterygian fishes, and the reptiles Pachystropheus and Ichthyosaurus, all of which are widely known from coeval sites. An unusual feature is the occurrence of an unidentified coelacanth, represented by nine isolated quadrates showing a broad range of sizes. The site has also provided information on the occurrence of vertebrates through five distinctive bone-bearing horizons, including the famous basal Westbury Formation bone bed, as well as a second horizon with bones at the top of the Westbury Formation, and three within the overlying Cotham Member of the Lilstock Formation. These show substantial differences, especially between the basal bone bed and the four overlying bone-rich units. The basal Westbury Formation bone bed is dominated by shark remains (73%, compared to 23–30% in the four overlying units), most notably, teeth of Rhomphaiodon minor and Lissodus minimus, which are absent or rare in higher beds. Further, teeth of the bony fishes Gyrolepis albertii and Severnichthys acuminatus are rare in the basal bone bed, but abundant at the top of the Westbury Formation and through the Cotham Member, and the sharks Duffinselache holwellensis and Pseudocetorhinus pickfordi, absent in the basal bone bed, are relatively abundant in the four overlying bone-bearing units. These differences in faunal lists and in relative proportions probably do not reflect sampling, but some major differences in ecology and evolution.

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.

Very diverse Early Permian chondrichthyan assemblages occur in the Asselian to Artinskian of the Middle and South Urals. They include numerous symmoriid teeth of “Denaea” decora Ivanov, Cobelodus obliquus sp. nov., Stethacanthus and Denaea; the teeth of the ctenacanthoid Heslerodus; the teeth of the synechodontiform Synechodus antiquus sp. nov.; and the teeth of taxa of doubtful affinities – Adamantina foliacea Ivanov, Cooleyella cf. C. fordi (Duffin & Ward), Cooleyella sp. A., as well the scales and denticles of various types. Two new species, Cobelodus obliquus and Synechodus antiquus, are described herein. The Early Permian chondrichthyan assemblages of Urals include a few taxa occurring only in that interval, as well taxa which were distributed in the Carboniferous and persisted into the Early Permian, such as Stethacanthus, Cobelodus, Denaea, “Denaea”, Lissodus, Heslerodus, “Symmorium”, Petalodus, Cooleyella and Adamantina. This occurrence of a synechodontid is the oldest in the world. The symmoriid sharks disappeared in the Middle Permian. The Permian shark faunas of the Urals contain a diverse assemblage of symmoriids, ctenacanthiods and synechodontiforms, but there are no xenacanthids were common in the Permian assemblages of Western Europe

The hybodont form genus Lissodus is taken under revision and found to comprise a number of lineages. Twelve species, stratigraphically extended from the Scythian, Lower Triassic to the Albian, Lower Cretaceous, are retained in Lissodus s.s. Thirteen other species can be included in Lonchidion, here considered as a justified genus, ranging from the Ladinian in the Middle Triassic to the Maastrichtian in the Upper Cretaceous. Of the species previously included in Lissodus, two new genera, Vectiselachos, gen. nov. and Parvodus, gen. nov., are described. Vectiselachos is at present a monotypic genus including a single species from the Lower Cretaceous of southern England. Parvodus comprises three species and is known from the Bathonian, Middle Jurassic to the Valanginian, Lower Cretaceous. Another species is placed in Steinbachodus, expanding the stratigraphical range of the genus from the Rhaetian in the Upper Triassic to the Cenomanian in the Upper Cretaceous. Palaeozoic small-toothed hybodonts are extremely poorly known and alleged Lissodus species fall into two genera, but these are at present kept in open nomenclature. The family Lonchidiidae is considered justified and includes the genera Lissodus, Lonchidion, Vectiselachos, Hylaeobatis and Parvodus.