Corals not serpulids: mineralized colonial fossils in the Lower Jurassic marginal facies of South Wales

Poorly preserved colonial corals occur near the base of the Lower Jurassic marginal facies at Southerndown, South Wales. Previously they have been interpreted as serpulid colonies, despite a dissimilarity to any serpulids known from elsewhere in the Lias or the few known extant colonial serpulids. However, local preservation of fine detail reveals evidence, in the form of corallites, septa and tabulae, that they are scleractinian corals of the Suborder Faviina, Family Stylophyllidae. These coral specimens occur in close association with barite–galena veins in the underlying Carboniferous Limestone and adjacent Lias marginal facies. Their widespread misindentification as ‘serpulid reefs’ is a consequence of coarse replacive mineralization by barite, which has largely obscured the diagnostic characters

A unique Valanginian paleoenvironment at an iron ore deposit near Zengővárkony (Mecsek Mts, South Hungary), and a possible genetic model

Abstract The spatially restricted Early Valanginian iron ore (limonite) and manganese deposit at Zengõvárkony (Mecsek Mts, southern Hungary) contains a rich, strongly limonitized, remarkably large-sized (specimens are 30–70% larger than those at their type localities) brachiopod-dominated (mainly Lacunosella and Nucleata) megafauna and a diverse crustacean microfauna, which indicates a shallow, nutrient-rich environment possibly linked to an uplifted block, and/or a hydrothermal vent

Chaetopterid tubes from vent and seep sites: Implications for fossil record and evolutionary history of vent and seep annelids

Vestimentiferan tube worms living at deep-sea hydrothermal vents and cold seeps have been considered as a clade with a long and continuing evolutionary history in these ecosystems. Whereas the fossil record appears to support this view, molecular age estimates do not. The two main features that are used to identify vestimentiferan tubes in the fossil record are longitudinal ridges on the tube's surface and a tube wall constructed of multiple layers. It is shown here that chaetopterid tubes from modern vents and seeps—as well as a number of fossil tubes from shallow-water environments—also show these two features. This calls for a more cautious interpretation of tubular fossils from ancient vent and seep deposits. We suggest that: current estimates for a relatively young evolutionary age based on molecular clock methods may be more reliable than the inferences of ancient “vestimentiferans” based on putative fossils of these worms; not all of these putative fossils actually belong to this group; and that tubes from fossil seeps should be investigated for chitinous remains to substantiate claims of their potential siboglinid affinities

Miocene abyssochrysoid gastropod Provanna from Japanese seep and whale - fall sites

We describe three Miocene species of Provanna from Japan, two new and one in open nomenclature, that represent the only known fossil examples from whale-falls and a considerable increase in the Miocene diversity of the genus. Provanna hirokoae sp. nov. comes from the latest Middle Miocene Kuroiwa seep site in central Honshu. The shells of this species are mostly recrystallized, but contain relict crossed lamellar microstructures. Provanna alexi sp. nov. is from the early Middle Miocene Shosanbetsu whale-fall site in northwestern Hokkaido, and has well preserved shells comprising an outer simple prismatic layer and an inner crossed lamellar layer. The two Provanna specimens from the Middle Miocene Rekifune whale-fall site, in eastern Hokkaido, are preserved as external moulds only, so are left in open nomenclature. Based on current knowledge, the presence of an outer prismatic layer and an underlying crossed lamellar layer seems to be a common feature in the shells of Provanna, as well as in other genera belonging to the family Provannidae and the superfamily Abyssochrysoidea. Although the oldest occurrence of Provanna was in the Late Cretaceous, the genus did not spread geographically and ecologically until the Miocene (with four, or possibly five species), a date concordant with some molecular estimates. However, this could be an artefact of the fossil record because the known pre-Miocene seep and whale-falls are more geographically restricted than those from the Miocene

A new fossil vent biota in the Ballynoe barite deposit, Silvermines, Ireland: Evidence for intracratonic sea-floor hydrothermal activity about 352 Ma

Considerable controversy exists as to the timing of the important Mississippian carbonate-hosted Irish-type Zn + Ph +/- Ba +/- Ag deposits. The Silvermines deposits have been defined as an end member of this style in that they have been interpreted to display textures indicative of sea-floor deposition. One of the strongest arguments in favor of this interpretation was the report of a hydrothermal vent field, including pyritic chimneys in the Ballynoe open-pit barite deposit. This paper adds to that body of evidence by describing a hydrothermal vent fauna from the same vent field, consisting of a delicately pyritized worm tube hosted by massive pyrite and hematized filaments of apparent microbial origin. The worm tube is remarkably similar to fossil worm tubes from modern and ancient volcanic-hosted massive sulfide deposits, and the filamentous microfossils have similarities to modern Fe-oxidizing bacteria. We have found no correlation between the worm tube and normal Mississippian fossils such as crinoids, whose replacement by pyrite in the immediately underlying Ballynoe footwall destroys original morphology. The sulfur isotope composition of the worm tube and host pyrite is essentially identical to that of the vent field pyrite and the main sulfide ore stage of Silvermines sulfides, all having a mean value about -20 per mil, indicating an open-system bacteriogenic sulfide source. These discoveries provide additional evidence for the exhalative nature of parts of the Silvermines orebodies, and imply that mineralization had begun in the Irish ore field by the late Tournaisian (similar to352 Ma)

Jurassic and Cretaceous gastropods from hydrocarbon seeps in forearc basin and accretionary prism settings, California

Fourteen gastropod species from 16 Mesozoic hydrocarbon seep carbonate deposits of the Great Valley Group and Franciscan Complex in California are described. Two genera are new: Bathypurpurinopsis has a fusiform shell with a siphonal fold, and variable Paskentana has turbiniform or littoriniform shells with spiral and/or scaly sculpture and convex or shouldered whorls. Due to the lack of data on shell microstructure and protoconch morphology, many of our taxonomic assignments have to remain tentative at present. Species that are described as new include: Hokkaidoconcha bilirata, H. morenoensis, H. tehamaensis (Hokkaidoconchidae), Abyssochrysos? giganteum (Abyssochrysidae?), Paskentana globosa, P. berryessaensis, and Bathypurpurinopsis stantoni (Abyssochrysoidea, family uncertain). The total fauna represents a mixed bag of taxa that were: (i) widely distributed during the late Mesozoic (Amberleya); (ii) restricted to late Mesozoic seep carbonates in California (Atresius, Bathypurpurinopsis, Paskentana); and (iii) members of seep/deep−sea groups with a long stratigraphic range (abyssochrysids, hokkaidoconchids)

A new fossil provannid gastropod from Miocene hydrocarbon seep deposits, East Coast Basin, North Island, New Zealand

Provanna marshallisp. nov. is described from Early to Middle Miocene−age fossil hydrocarbon seep localities in the East Coast Basin, North Island, New Zealand, adding to 18 modern and three fossil species of the genus described. Modern species are well represented at hydrothermal vent sites as well as at hydrocarbon seeps and on other organic substrates in the deep sea, including sunken wood and whale falls. Described fossil Provanna species have been almost exclusively reported from hydrocarbon seep deposits, with a few reports of suspected fossil specimens of the genus from other chemosynthetic environments such as sunken wood and large vertebrate (whale and plesiosaurid) carcasses, and the oldest occurrences are dated to the Middle Cenomanian (early Late Cretaceous). The New Zealand fossil species is the most variable species of the genus described to date, and its shell microstructure is reported and found to be comparable to the fossil species Provanna antiqua and some modern species of the genus

The geological history of deep-sea colonization by echinoids: roles of surface productivity and deep-water ventilation

The origins and geological history of the modern fauna of deep-sea echinoids is explored using a combination of palaeontological and molecular data. We demonstrate that, whereas generalist omnivores have migrated into the deep sea in low numbers over the past 200 Myr, there was a short time-interval between approximately 75 and 55 Myr when the majority of specialist detritivore clades independently migrated off-shelf. This coincides with a marked increase in seasonality, continental run-off and surface water productivity, and suggests that increasing organic carbon delivery into ocean basins was an important controlling factor. Oceanic anoxic events, by contrast, appear to have played a subsidiary role in controlling deep-sea diversity