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Middle Carboniferous to Early Permian bryozoans from Spitsbergen

100%

Nakrem H. A.

Acta Palaeontologica Polonica

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1994

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tom 39

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nr 1

45-116

Bryozoans from the Nordenskiöldbreen Formation (Middle Carboniferous Moscovian through Early Permian Sakmarian) and the Gipshuken Formation (late Sakmarian - late Artinskian), from central Spitsbergen, Svalbard, are represented by 36 species (22 genera). One species is new: Hinaclema svalbardensis of the order Trepostomata. The bryozoan fauna is typical Boreal and resembles those from the Timan-Pechora region (western Siberia) and the Urals. Similarity indices based on generic composition show that the Boreal fauna became more endemic by the late Early Permian, clearly separated from the Tethyan faunas. Several species have stratigraphic ranges in Spitsbergen longer than elsewhere.

2

Enrolment in a Middle Ordovician agnostoid trilobite

63%

Bruton D. L., Nakrem H. A.

Acta Palaeontologica Polonica

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2005

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tom 50

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nr 3

Study of silicified material of Trinodus elspethi, from the Edinburg Formation, Virginia, USA, shows there is no gliding of distal parts of segments but an articulating furrow and opposing flange with prongs, acting as apodemes for muscle attachment, allowed cephalon and thorax to move as a single unit. Articulation between thorax and pygidium was more rigid with prongs from the thorax articulating in sockets on the pygidium. Support is given to the view that agnostoids lived partially enrolled with cephalon and pygidium gaping. They are unique in lacking an articulating half−ring between cephalon and thorax and the hinge joint is modified medially to provide an opening for what is interpreted as an exhalatory organ through which water passed during feeding and swimming. Peculiarities of the thorax are connected with the presence of only two thoracic segments articulating as a unit with distal tips directed anteriorly rather than posteriorly. Otherwise articulating half rings are present in the rest of the thorax and pygidium and lack of articulating facets is not unique. It is concluded that agnostoids can be shown to be trilobites.

3

Lower Permian bryozoans from southern and central Spitsbergen, Svalbard

51%

Nakrem H. A., Blazejowski B., Gazdzicki A.

Acta Palaeontologica Polonica

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2009

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tom 54

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nr 4

Bryozoans from the Lower Permian Treskelodden and Wordiekammen formations of southern and central Spitsbergen respectively, Svalbard, have been studied. Twenty species are identified, including one new genus, Toulapora gen. nov., with Toulapora svalbardense as type species and one new species, Ascopora birkenmajeri sp. nov. The taxonomic composition is typical Lower Permian, with species in common with Timan−Pechora and the Urals (Russia) and Ellesmere Island (the Canadian Arctic). Growth habits reflect a moderately to deeper shelf environment.

4

Permian-Triassic scolecodonts and conodonts from the Svalis Dome, Central Barents Sea, Norway

51%

Nakrem H. A., Szaniawski H., Mork A.

Acta Palaeontologica Polonica

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2001

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tom 46

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nr 1

Scolecodonts and conodonts are described from five samples of three cores from the Svalis Dome, central Barents Sea. The conodont species Mesogondolella rosenkrantzi and Neospathodus svalbardensis confirm latest Permian (Dzulfian) and earliest Triassic (Dienerian) ages for the investigated intervals. Correlation with adjacent conodont distribution indicates a shorter depositional gap in the late Permian than is evident on Svalbard. The conodont elements show little thermal alteration with CAI (colour alteration index) values between 1.0 and 1.5 indicating a maximum burial temperature of 50—90°C. The scolecodonts described herein have important evolutionary and distribution implications for polychaetes: the order Eunicida shows a richer diversification in the Permian than previously known; the family Paulinitidae survived at least until the Late Permian; the family Hartmaniellidae diversified already in the late Palaeozoic; some forms are considered as representatives of unknown species and genera; the order Phyllodocida originated already in the latest Palaeozoic.

5

Large Onychites (Cephalopod Hooks) from the Upper Jurassic of the Boreal Realm

39%

Hammer O., Hryniewicz K., Hurum J. H., Hoyberget M., Knutsen E. M., Nakrem H. A.

Acta Palaeontologica Polonica

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2013

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tom 58

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nr 4

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.

Ograniczanie wyników

5 Acta Palaeontologica Polonica

5 Nakrem H. A.

1 Blazejowski B.

1 Bruton D. L.

1 Gazdzicki A.

1 Hammer O.

1 Hoyberget M.

1 Hryniewicz K.

1 Hurum J. H.

1 Knutsen E. M.

1 Mork A.

1 Szaniawski H.

1 2013

1 2009

1 2005

1 2001

1 1994

Middle Carboniferous to Early Permian bryozoans from Spitsbergen

Enrolment in a Middle Ordovician agnostoid trilobite

Lower Permian bryozoans from southern and central Spitsbergen, Svalbard

Permian-Triassic scolecodonts and conodonts from the Svalis Dome, Central Barents Sea, Norway

Large Onychites (Cephalopod Hooks) from the Upper Jurassic of the Boreal Realm