Early-Middle Ordovician cephalopods from Ny Friesland, Spitsbergen - a pelagic fauna with Laurentian affinities Author Kröger, Björn 72F166B6-51DC-4DD8-9DEE-47EDDEE3D2F2 Finnish Museum of Natural History, University of Helsinki, PO Box 44, FI- 00014 Helsinki, Finland. bjorn.kroger@helsinki.fi Author Pohle, Alexander 9C9B621D-7A77-41FF-8B63-DD21BEE10B56 Paläontologisches Institut und Museum, University of Zurich, Zurich, Switzerland. alexander.pohle@pim.uzh.ch text European Journal of Taxonomy 2021 2021-12-20 783 1 1 102 http://dx.doi.org/10.5852/ejt.2021.783.1601 journal article 2884 10.5852/ejt.2021.783.1601 aa9de9bf-dea4-4321-a51d-6c4f1f55032d 2118-9773 5793422 071EAD63-05ED-4D6C-AC45-8719E6D79E0B Svalbardocreas skua gen. et sp. nov. urn:lsid:zoobank.org:act: 9385D872-8656-4B53-9CA8-05F7575BEB6F Figs 16B , 19C , 20–21 , 22A–D , 23B, D, F Diagnosis Slightly curved longicones with circular conch cross section; shell ornamented with shallow, irregularly spaced undulations that are more pronounced in later growth stages and with fine, irregularly spaced, directly transverse growth lines or bands; thin, nearly marginal siphuncle with relative siphuncle diameter of ca 0.16 of corresponding conch cross section, siphuncle positioned at concave side of conch curvature; septal necks orthochoanitic; connecting ring relatively thick with slightly concave segments, weak hyposeptal and episeptal deposits occur. Etymology Referring to Stercorarius skua (Brünnich, 1764) , a bird which was a common companion during our field work at Profilstranda, Ny Friesland . Type material Holotype Specimen FMNH-P30272 . Paratypes Nine specimens from type locality, one from bed PO 123 ( FMNH-P30271 ), eight from bed PO 123.3 ( FMNH-P30263 , P30264 , P30273 , P30275 to P30277 , P30408 , P30471 ), 120–120.3 m above the base of the Olenidsletta Member , V2 a trilobite zone , Blackhillsian , Floian . Type locality and horizon From Profilstranda section, adjacent to Hinlopenstretet, Spitsbergen, bed PO 123.3, 120.3 m above the base of the Olenidsletta Member, V 2a trilobite zone, Blackhillsian, Floian. Fig. 20. Diagrams of relative conch width and angles of expansion of species of Svalbardoceras gen. nov. from the Olenidsletta Member, Floian, Ordovician, Profilstranda section, Ny Friesland, Spitsbergen. See Supp. file 1 for details of measurements. Description The conchs are slightly curved with angle of expansion of <ca 7° (mean angle of expansion = 4.8°, 1 st –3 rd quantile: 3.3–4.8; n = 7), which decreases with conch size from ca 11° to 5° ( Figs 20 , 22A–D ). The conch cross section is invariantly circular. The conch surface is ornamented with fine growth lines or growth bands ( Fig. 29C ) and annulations, which are slightly obliquely transverse, and shifted toward the aperture at the antisiphuncular side. The sutures are slightly obliquely transverse and shifted toward the aperture at the antisiphuncular side. The relative chamber length (rCL) decreases with increasing conch cross section ( Fig. 21 ), ranging from ca 0.25 to more than 0.3. The siphuncle is marginally positioned, very slightly removed from the conch margin ( Fig. 23B ), at the concave side of the conch curvature with a mean rSD of 0.16 (1 st –3 rd quantile: 0.13–0.19; n = 4). The septal necks are orthochoanitic. The connecting ring is moderately thick and forms slightly concave siphuncular segments ( Fig. 23F ). Weak epi-, and hyposeptal deposits occur in the extreme apical part of specimen FMNH-P30274 at a conch height of ca < 2.8 mm . In one specimen part of the body chamber is preserved (specimen FMNH-P30276); the body chamber is> 26 mm long and the conch diameter at the position of the last septum is 5.5 mm . Comparison See above, under Svalbardoceras sterna gen. et sp. nov.