Agardhfjellet (Jurassic of Norway)

Where: Spitsbergen, Norway (78.1° N, 18.8° E: paleocoordinates 69.4° N, 17.4° E)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Slottsmøya Member (Agardhfjellet Formation), Tithonian (152.1 - 145.0 Ma)

• Upper part of the Slottsmøya Member, Agardhfjellet Formation, Janusfjellet, Middle Volgian (Tithonian; Nagy & Basov, 1998; Collignon & Hammer 2012; Gradstein et al. in press).

•From either the Dorsoplanites maximus or D. ilovaiskyi zone, corresponding to the Middle Volgian.

•The stratigraphic occurrence of the 1976 specimen (PMO 218.377) was also unknown. δ13C analyses of shale collected along with the specimen were compared with the δ13C curve for the entire Slottsmøya Member (see Collignon & Hammer, this volume). The results of this analysis indicate that this specimen was either found between 31-22 metres or 15-11 metres below the Dorsoplanites Bed (Collignon & Hammer, this volume).

Environment/lithology: deep-water; concretionary, sideritic, black, gray, silty mudstone

• The Slottsmøya Member was deposited in an open marine environment under oxygen-deficient settings (Nagy et al., 1988; Dypvik et al., 1991b). Paleogeographic reconstructions for Svalbard during the Kimmeridgian to Valanginian interval place paleoshorelines several hundred kilometres to the north and west (Dypvik et al., 2002).
• The Slottsmøya Member, which ranges from 70 to 100 metres in thickness in the study area, consists of dark grey to black silty mudstone, often weathering to paper shale, discontinuous silty beds, with local occurrences of red to yellowish sideritic concretions as well as siderite and dolomite interbeds (Dypvik et al., 1991a; Hammer et al., 2011; Collignon & Hammer, this volume).

Size class: macrofossils

Collected by an expedition from the Norwegian Polar Institute, led by Mark Edwards in 1976

Collection methods: surface (in situ),

• PMO, Natural History Museum, University of Oslo collection

Primary reference: E. M. Knutsen, P. S. Druckenmiller, and J. Hurum. 2012. Redescription and taxonomic clarification of ‘Tricleidus’ svalbardensis based on new material from the Agardhfjellet Formation (Middle Volgian). Norwegian Journal of Geology 92:175-186 [R. Benson/R. Benson]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 134740: authorized by Roger Benson, entered by Roger Benson on 15.10.2012

Creative Commons license: CC BY (attribution)

Taxonomic list

 Sauropterygia - Cryptoclididae
Colymbosaurus svalbardensis Persson 1962 plesiosaur
PMO 218.377, which includes two partial propodials, the larger articulated with the nearly complete distal limb