Cambrian (Series 3 – Furongian) conodonts from the Alum Shale Formation at Slemmestad, Oslo Region, Norway

Nine samples from the Alum Shale of Slemmestad, Oslo Region, were processed for conodonts. The limestone-rich interval extending from the mid Cambrian Paradoxides paradoxissimus trilobite Zone to the Lower Ordovician Boeckaspis trilobite Zone yielded a sparse conodont fauna. The fauna is dominated by the protoconodont species Phakelodus elongatus (Zhang in An et al., 1983) and Phakelodus tenuis Müller, 1959, the paraconodont species Westergaardodina polymorpha Müller & Hinz, 1991, Westergaardodina ligula Müller & Hinz, 1991, Problematoconites perforatus Müller, 1959 and Trolmenia acies Müller & Hinz, 1991; the euconodont species Cordylodus proavus Müller, 1959 is present in the Acerocarina Superzone. The presence of the cosmopolitan Cordylodus proavus Müller, 1956 at Slemmestad provides an important tie for regional and international correlation.publishedVersio

Scale dependent diversity of bryozoan assemblages in the reefs of the Late Ordovician Vasalemma Formation, Estonia

The fieldwork for BK and AP was partly funded by the Academy of Finland project ‘Ecological Engineering as a Biodiversity Driver in Deep Time’ (Decision No. 309422). Deutsche Forschungsgemeinschaft (DFG) is appreciated for financial support of AE (project ER 278/10.1). The work is a contribution to the IGCP program 735 ‘Rocks and the Rise of Ordovician Life’.The reefs of the Vasalemma Formation, late Sandbian, Late Ordovician, of northern Estonia contain an exceptional rich and abundant bryozoan fauna. They are an example of contemporaneous bryozoan-rich reefs known from around the world, representing the peak diversification interval of this group during the Ordovician. The global Ordovician bryozoan diversification was associated with a decrease in provinciality, a pattern known from other skeletal marine metazoans of this period. The diversification is associated with climatic cooling and increasing atmospheric and sea water oxygenation. However, the mechanisms that led to the bryozoan diversification are poorly known. Here we estimate the bryozoan richness (α and γ diversity) and turnover (β diversity) at the level of samples, reefs, and formations in the Vasalemma Formation and in contemporaneous reef limestone occurrences of the Baltoscandian region. The resulting richness and turnover values differ among the three observational levels and hence are scale dependent. A consistent pattern with lowest between-reef turnover and relatively high between-sample turnover could be detected, reflecting high small-scale (within reef) heterogeneities in lithology and original bryozoan habitat. This is consistent with published work, in which evidence has been presented for small-scale substrate heterogeneity as the most important diversification driver of the Ordovician brachiopod diversification in the Baltoscandian region. The fact that reefs and their local substrate are strongly organism moderated environments sheds light on the potentially important ecosystem engineering role of organisms, such as bryozoans, for the Ordovician diversification.Publisher PDFPeer reviewe

A Cambrian–Ordovician boundary section in the Rafnes–Herøya submarine tunnel, Skien–Langesund District, southern Norway

Rock specimens and contained fossils collected in 1976 from a submarine tunnel driven between Herøya and Rafnes in the Skien–Langesund area of southern Norway, have been restudied. The contained fossils include olenid and agnostoid trilobites, graptolites and brachiopods, groups described in detail for the first time from the area and documenting a Cambrian–Ordovician boundary section unique in the district where the upper Cambrian Alum Shale Formation is elsewhere overlain by the Middle Ordovician Rognstranda Member of the Huk Formation (Kundan in terms of Baltoscandian chronostratigraphy). The hiatus at the base of the Huk Formation is thus smaller in the section described herein, beginning at a level within rather than below the Tremadocian. Estimated thickness of the Alum Shale includes 10–12 m of Miaolingian and 20–22 m of Furongian strata with trilobite zones identified, and a Tremadocian section of 8.1 m identified by species of the dendroid graptolite Rhabdinopora in the basal 2.6 m and Bryograptus ramosus at the top. The Tremadocian section is preserved in a postulated zone of synsedimentary subsidence along the Porsgrunn–Kristiansand Fault Zone, while at the same time there was extensive erosion across an emergent, level platform elsewhere in the Skien–Langesund District and the southern part of the Eiker–Sandsvær District to the north. Aspects of stratigraphy and tectonics are highlighted together with a discussion on the Cambrian– Ordovician boundary locally and worldwide

Diversity and spatial turnover of bryozoan assemblages in the reefs of the Vasalemma Formation (Late Ordovician), Estonia

The reefs of the Vasalemma Formation, late Sandbian, Late Ordovician, of northern Estonia contain an exceptionally rich and abundant bryozoan fauna. They are an example of contemporaneous bryozoan-rich reefs known from around the world, representing the peak diversification interval of this group during the Ordovician. The diversification is associated with global climatic cooling and increasing atmospheric and sea water oxygenation. However, the mechanisms that led to the bryozoan diversification are poorly known. Here we estimate the bryozoan richness (α and γ diversity) and turnover (β diversity) at the level of samples, reefs, and formations in the Vasalemma Formation. The resulting richness and turnover values differ among the three observational levels and hence are scale dependent. A pattern with lowest between-reef turnover and relatively high between-sample turnover could be detected, reflecting high small-scale (within reef) heterogeneities in lithology and original bryozoan habitat. This is consistent with the hypothesis that small-scale substrate heterogeneity was the most important diversification driver in the Vasalemma Formation

Late Jurassic–Early Cretaceous hydrocarbon seep boulders from Novaya Zemlya and their faunas

The paper describes Late Jurassic–Early Cretaceous seep carbonate boulders from the Russian Arctic island of Novaya Zemlya, collected in 1875 by A.E. Nordenskiöld during his expedition to Siberia. The carbonates are significantly depleted in heavy carbon isotopes (δ13C values as low as ca. − 40‰) and show textures typical for carbonates formed under the influence of hydrocarbons, such as fibrous carbonate cements and corrosion cavities. The rocks contain index fossils of Late Oxfordian–Early Kimmeridgian, Late Tithonian (Jurassic) and latest Berriasian–Early Valanginian (Cretaceous) age. The fossil fauna is species rich and dominated by molluscs, with subordinate brachiopods, echinoderms, foraminifera, serpulids and ostracods. Most of the species, including two chemosymbiotic bivalve species, likely belong to the ‘background’ fauna. Only a species of a hokkaidoconchid gastropod, and a possible abyssochrysoid gastropod, can be interpreted as restricted to the seep environment. Other seep faunas with similar taxonomic structure are suggestive of rather shallow water settings, but in case of Novaya Zemlya seep faunas such structure might result also from high northern latitude

Paleocene methane seep and wood-fall marine environments from Spitsbergen, Svalbard

A recently discovered Paleocene seep locality from Fossildalen on Spitsbergen, Svalbard, is described. This is one of a very few seep communities of the latest Cretaceous–earliest Palaeogene age, and the best preserved Paleocene seep community known so far. The seep carbonates and associated fossils have been first identified in museum collections, and subsequently sampled in the field. The carbonates are exclusively ex-situ and come from the offshore siltstones of the Basilika Formation. Isotopically light composition (δ13C values approaching -50‰ V-PDB), and characteristic petrographic textures of the carbonates combined with the isotopically light archaeal lipid are consistent with the formation at fossil hydrocarbon seep. The invertebrate fauna associated with the carbonates is of moderate diversity (16 species) and has a shallow water affinity. It contains a species of the thyasirid genus Conchocele, common in other seeps of that age. The finding sheds new light onto the history of seepage on Svalbard, and onto the evolution and ecology of seep faunas during the latest Cretaceous–earliest Palaeogene time interval

Hokkaidoconcha Kaim, Jenkins & Waren 2008

<i>Hokkaidoconcha</i> sp. <p>(Fig. 5I –M)</p> <p> 2015 Hokkaidoconchidae gen. et sp. indet.; Hryniewicz <i>et al.</i> 2015a, table 1.</p> <p> <b>Description.</b> Cerithioid shell with opisthocline to slightly opisthocyrt axial ribs and fine numerous spiral riblets. Whorl flanks are weakly inflated and the suture weakly incised. Protoconch and aperture not preserved.</p> <p> <b>Material and occurrence:</b> Three specimens from seep #12, Sassenfjorden, Svalbard; late Berriasian (Early Cretaceous). All illustrated: PMO 217.507, PMO 217.509, PMO 217.511b.</p> <p> <b>Remarks.</b> <i>Hokkaidoconcha</i> sp. is represented by three incompletely preserved juvenile specimens, so several pertinent shell characters could not be observed, and this is the reason why we decided to leave this species in open nomenclature. Our <i>Hokkaidoconcha</i> sp. from Svalbard is most similar to juveniles of the Cenomanian <i>H. tanabei</i> from Japan (Kaim <i>et al.</i> 2008b). The latter species, however, grows to a relatively large size and its ornament changes with ontogeny. Changes in ontogeny could not be observed in <i>Hokkaidoconcha</i> sp. from Svalbard due to the fragmentary preservation. Another similar species is <i>H. occidentalis</i> (Stanton, 1895) from the Late Jurassic– Early Cretaceous of California (Kiel <i>et al.</i> 2008; Kaim <i>et al.</i> 2014) which seems, however, to have a much weaker developed spiral ornamentation and stronger axial ribs. <i>Hokkaidoconcha hignalli</i> Kaim & Kelly, 2009 from the Tithonian (Late Jurassic) Gateway Pass seep on Alexander Island, Antarctica, loses the ornamentation during ontogeny and may thus actually belong to the genus <i>Hudlestoniella</i> (see below). Superficially, <i>Hokkaidoconcha</i> sp. is similar to juvenile specimens of <i>Hudlestoniella hammeri</i> (see below), but it differs in having stronger and persistent spiral ornament (which at the size of <i>Hokkaidonconcha</i> sp. already fades away in <i>H. hammeri</i>) and opistocline to weakly opistocyrt axial ribs, rather than strongly opistocyrt ribs as observed in <i>H. hammeri</i>.</p>Published as part of <i>Nakrem, Hans Arne, 2017, Gastropods from the Late Jurassic - Early Cretaceous seep deposits in Spitsbergen, Svalbard, pp. 351-374 in Zootaxa 4329 (4)</i> on page 358, DOI: 10.11646/zootaxa.4329.4.3, <a href="http://zenodo.org/record/1003014">http://zenodo.org/record/1003014</a&gt

Cretadmete Blagovetshenskiy & Shumilkin 2006

<i>Cretadmete</i> sp. <p>(Fig. 8A–C)</p> <p> 2015 Maturifusidae? gen. et sp. indet.; Hryniewicz <i>et al.</i> 2015a, table 1.</p> <p> <b>Description.</b> Protoconch not preserved. Shell small, 4.5 mm in height and 5.3 mm in width, fusiform/turbiniform with two strongly convex whorls preserved. Suture moderately incised. Shell flank ornamented with numerous spiral cords arranged in two orders; each two 1 st order cords sandwich one weaker 2nd order cord. The spiral ornament is crossed by prosocline axial ridges with no clear knobs and the intersections, which, however, might be slightly undulating in the adapical portion of flank. Transition between flank and base without angulation, but distinct due to disappearance of axial ornamentation and 2nd order spiral cords. Aperture poorly preserved with no apertural elaborations visible. Anterior part of the aperture broken off. No umbilicus.</p> <p> <b>Material and occurrence:</b> One specimen (PMO 224.762) from seep deposit #8, Sassenfjorden, Svalbard; Late Tithonian, Late Jurassic.</p> <p> <b>Remarks.</b> This juvenile shell is remarkably similar to <i>Cretadmete neglecta</i> Blagovetshenskiy & Shumilkin, 2006, from the Upper Hauterivian (Early Cretaceous) of the Ulyanovsk Region in Russia. Blagovetshenskiy & Shumilkin (2006) included six species in <i>Cretadmete</i> ranging in age from the Oxfordian to the Albian. We refrain from placing our shell into any of these species due to its fragmentary preservation. A similar type of teleoconch, but with entirely different cancellate protoconch, has been reported by Schröder (1995: pl. 7: 3–4) in a juvenile shell from the Albian of Germany, which has been interpreted by Bandel (1993) as a species of <i>Rapana</i> and considered by him to be the oldest record of the tonnoideans. Wollemann (1900, 1907, 1909) reported from the same strata several species similar to <i>Cretadmete</i> (but without protoconchs); this entire group of taxa requires thorough review.</p>Published as part of <i>Nakrem, Hans Arne, 2017, Gastropods from the Late Jurassic - Early Cretaceous seep deposits in Spitsbergen, Svalbard, pp. 351-374 in Zootaxa 4329 (4)</i> on page 363, DOI: 10.11646/zootaxa.4329.4.3, <a href="http://zenodo.org/record/1003014">http://zenodo.org/record/1003014</a&gt

Eucycloidea bitneri Nakrem 2017, sp. nov.

<i>Eucycloidea bitneri</i> sp. nov. <p>(Fig. 4)</p> <p> 2011 <i>Eucyclus</i> sp.; Hammer <i>et al.</i> 2011, fig. 7l,</p> <p> 2015 <i>Ambercyclus</i> sp.; Hryniewicz <i>et al.</i> 2015a, table 1.</p> <p> <b>Diagnosis.</b> Shell trochiform, with strong, nodose medial keel, nodes merge later into band. Flank ornamented by dense network of tiny axial and spiral riblets. Base with strong spiral ribs.</p> <p> <b>Holotype:</b> PMO 217.235, H = 46 mm, W = 33 mm.</p> <p> <b>Type locality and age:</b> Seep #3, Sassenfjorden, Svalbard; late Tithonian, Late Jurassic.</p> <p> <b>Other material:</b> Fourteen specimens from seep #3, three specimens from seep #9, and two specimens from seep #13 (Table 1).</p> <p> <b>Description.</b> Protoconch unknown. Shell trochiform with strong medial keel. Additional keels are present just at the adapical and abapical suture. The lateral flank is covered by numerous fine axial riblets. Above the medial keel, the riblets are strongly opisthocyrt while below the medial keel only weakly opisthocyrt. The medial keel is covered by a series of blunt, smooth and wide nodes, the other keels are intersected by axial riblets though later in ontogeny these ribs become similar to the medial keel and the nodes on medial keel tend to merge into single band. The intersection of axial riblets and abapical keel is strongly inclined prosoclinally. The inter-keel surfaces are concave and ornamented by tiny spiral grooves (striae). The base is ornamented by 4–6 strong spiral ribs and tiny prosocline axial riblets. Growth lines strongly prosocline. Aperture, umbilicus, inner and outer lip not preserved.</p> <p> <b>Remarks.</b> <i>Eucycloidea bitneri</i> differs from other species in the genus by having an exceptionally strong spiral keel with nodes merging into a band. It also possesses delicate reticulate ornament on the lateral flank. The type species, <i>E. bianor</i> (d’Orbigny, 1850) differs by possessing additional tiny nodes on the intersection of axial and spiral riblets (Gründel 1997, 2003). <i>E. tenuistria</i> (Münster, 1844) (in Goldfuss 1844) from the Aalenian (Middle Jurassic) of Germany has weaker and less rounded nodes on the keel (Schulbert & Nützel 2013). The Middle Jurassic <i>E. granulata</i> (Hébert & Eudes-Deslongschamps, 1860) from France differs by possessing spiral riblets also on the keel (Gründel 2000). The Middle Jurassic <i>E. badamuensis</i> Ferrari <i>et al.</i>, 2016 from Iran (Ferrari <i>et al.</i> 2016) differs by having more pronounced spiral cords rather than tiny riblets, and regularly spaced and clearly separated nodes on the keel throughout ontogeny. The juvenile specimens (Fig. 4D, PMO 224.753) from late Berriasian seep # 9 may represent another species, as they have smaller and more numerous spiral ribs on the base (Fig. 4D) than the specimens from the Tithonian localities.</p> <p> <b>Distribution.</b> Seep #3 (late Tithonian); seep #9 (late Berriasian), and seep #13 (late Tithonian); Sassenfjorden, Svalbard.</p> <p> <b>Etymology.</b> In honour of Maria Aleksandra Bitner, a specialist of fossil and modern brachiopods.</p>Published as part of <i>Nakrem, Hans Arne, 2017, Gastropods from the Late Jurassic - Early Cretaceous seep deposits in Spitsbergen, Svalbard, pp. 351-374 in Zootaxa 4329 (4)</i> on pages 356-357, DOI: 10.11646/zootaxa.4329.4.3, <a href="http://zenodo.org/record/1003014">http://zenodo.org/record/1003014</a&gt