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Mandal, Norway

Hoyberget M.,Rennesveien 14 | Ebbestad J.O.R.,Uppsala University | Funke B.,Gjellerasveien 10 | Nakrem H.A.,University of Oslo
Norsk Geologisk Tidsskrift

New, extensive fossil material collected in situ from the lower Cambrian Evjevik Member in the Mjøsa type area, southern Norway, allows a reevaluation of the faunal distribution and diversity of the ‘Ornamentaspis’ linnarssoni Zone. Described taxa include three holmiid, six ellipsocephalid and one eodiscoid trilobite in addition to five helcionelloid molluscs. A Holmia species with affinities to the Swedish H. lapponica is common in the Evjevik Member. Librigenae, thoracic segments and pygidia from the poorly known, but biostratigraphically important trilobite ’Ornamentaspis’ linnarssoni (Kiær, 1917) are documented for the first time. The species is redescribed and transferred to Ellipsocephalus. Helcionelloid molluscs are represented by Helcionella antiqua (Kiær, 1917), Stenotheca norvegica (Resser, 1938), Mackinnonia puppis n. sp., Mackinnonia? sp. and Latouchella sp. These are similar to taxa reported from coeval strata at Gislövshammar in southern Sweden and may prove to have biostratigraphical potential. The Holmia kjerulfi Zone, the Ellipsocephalus linnarssoni Zone and the Comluella? scanica–Ellipsocephalus lunatus Zone are readily recognised in the Lower Allochthon of the Mjøsa area and are in this report treated as distinctive, successive zones. New illustrations are provided of the brachiopod Magnicanalis rotundata (Kiær, 1917), together with the enigmatic fossil Mongolitubulus Missarzhevsky, 1977, recorded for the first time in Norway. © the authors. Source

Hammer O.,Natural History Museum | Hryniewicz K.,Natural History Museum | Hurum Jo.H.,Natural History Museum | Hoyberget M.,Rennesveien 14 | And 2 more authors.
Acta Palaeontologica Polonica

We report on the discovery of large cephalopod arm hooks (mega-onychites) from the Kimmeridgian and Volgian of Spitsbergen (Agardhfjellet Formation). This includes a largely uncompressed hook in a seep carbonate,with preservation of surface sculpture. We suggest the use of logarithmic spirals as morphological descriptors for the outer part of cephalopod arm hooks, with implications for systematics and functional morphology. Comparison with Upper Jurassic material from Greenland, northern Norway and the North Sea demonstrates a remarkably consistent morphology, which we assign to the same form species, Onychites quenstedti. Considering the relatively small stratigraphic (Kimmeridgian - Volgian) and biogeographic (Boreal) range of this large form, it is likely that it represents a single biological species or genus. © Copyright © 2013 Ø. Hammer et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Source

Hoyberget M.,Rennesveien 14 | Bruton D.L.,University of Oslo
Norsk Geologisk Tidsskrift

A section through Furongian strata in the classical Slemmestad area of the Oslo Region, Norway, is described together with collected new material of selected zonal trilobites and their stratigraphical ranges within the Alum Shale Formation. This includes hitherto unknown mature and immature pygidia of certain species of Sphaerophthalmus, allowing the distinction between this and Ctenopyge to be clarified. Seven Sphaerophthalmus species are described of which five have previously been assigned to Ctenopyge (Eoctenopyge), a taxon considered redundant. These are Sphaerophthalmus angustus (Westergård, 1922), S. drytonensis (Cobbold, 1934), S. flagellifer Angelin, 1854, S. modestus (Henningsmoen, 1957) and S. postcurrens (Westergård, 1944). Others are the type species, S. alatus (Boeck, 1838) and S. arcus n. sp. Triangulopyge n. gen. is proposed for a small, but distinct group of olenids earlier assigned to Sphaerophthalmus. The new genus includes T. humilis (Phillips, 1848), T. major (Lake, 1913) and T. majusculus (Linnarsson, 1880). It is proposed that the Ctenopyge affinis Zone be replaced by a broadened Ctenopyge tumida Zone. The round and reduced exoskeletal spines of the Sphaerophthalmus species, rather than the very long and flattened exoskeletal spines of Ctenopyge, suggest that the former were adapted for a more pelagic life style. Source

Hammer O.,Natural History Museum | Nakrem H.A.,Natural History Museum | Little C.T.S.,University of Leeds | Hryniewicz K.,Natural History Museum | And 5 more authors.
Palaeogeography, Palaeoclimatology, Palaeoecology

Fifteen carbonate bodies, interpreted as having been formed at hydrocarbon seeps, have been found in the Sassenfjorden area of Spitsbergen, Svalbard. The bodies, up to 5m wide, are found in the siltstones and mudstones of the uppermost Slottsmøya Member, in the Upper Jurassic to lowermost Cretaceous Agardhfjellet Formation. The age of the seeps is close to the Volgian-Ryazanian (Jurassic-Cretaceous) boundary, and the Mjølnir impact event in the Barents Sea. The Sassenfjorden area carbonates show complex and heterogeneous structures typical of hydrocarbon seeps, including zoned (botryoidal) cement textures, fissure-infilling sparite, and breccias. Stable isotope analyses show highly negative δ13C values (down to ca. -43‰ VPDB) in the zoned carbonate cements, consistent with authigenic precipitation in a hydrocarbon-rich environment. Oxygen isotopes indicate secondary hydrothermal activity. The species-rich, well-preserved fauna includes at least 13 species of small to medium sized bivalves, some of which are abundant, as well as rarer rhynchonelliform and lingulid brachiopods, gastropods, echinoderms, sponges, and serpulid and probable vestimentiferan worm tubes. Although several bivalves (solemyids, lucinids, and probably Thyasira and Nucinella) had chemosymbionts, the Sassenfjorden seep fauna contains few, if any, seep obligate taxa, consistent with formation in a relatively shallow-water paleoenvironment. The seeps contain the earliest record of thyasirid bivalves, and a species-rich (six) brachiopod fauna including the first lingulid recorded in a seep environment. Ammonites, belemnites and large wood fragments represent ex situ fossils in the seep carbonate bodies. © 2011 Elsevier B.V. Source

Cederstrom P.,Axelvoldsvagen 27 | Ahlberg P.,Lund University | Babcock L.E.,Lund University | Babcock L.E.,Ohio State University | And 3 more authors.

The ellipsocephalid trilobite Strenuaeva spinosa occurs widely in Scandinavia in the lower part of the Ornamentaspis? linnarssoni Zone (Cambrian Series 2). Its first appearance is a readily recognisable, widespread biohorizon in Scandinavia. During ontogeny, intergenal spines are lost and the librigenae develop from a generative zone in the genal region. The palpebro-ocular ridges are distinct and connected to the posterior part of the frontal glabellar lobe in the early meraspid period, but eye ridges become separate from the palpebral lobes and the glabella in the late meraspid period. S. spinosa is characterised by large genal spines, distinct axial spines and falcate pleural tips. The spines may have functioned in predation resistance. S. spinosa also has a small pointed projection at the anterolateral corners of some thoracic pleurae, the function of which is unknown. The presence of five furrows in the cephalic axial lobe of S. spinosa, best expressed in meraspides, suggests that the head of this ellipsocephalid trilobite was composed of six fused primary segments. © 2012 Copyright Geologiska Föreningen. Source

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