Fig 1.
Map showing six ichthyosaur specimens from the Slottsmøya Member Lagerstätte discussed in the text (red dots).
Overview map (left corner) shows the Svalbard archipelago and island of Spitsbergen; orange dot corresponds to excavation area. Adapted from Hurum et al. (2012).
Fig 2.
Stratigraphic section for the Slottsmøya Member Lagerstätte showing the six ichthyosaur specimens with pelvic girdles discussed in the text (newly described material shown in bold).
Modified from Delsett et al. (2016).
Fig 3.
Skeletal map of Keilhauia nui (PMO 222.655) viewed from the side stratigraphically down, i.e. the prepared side.
Vertebrae numbers (“x#”) indicate position relative to the anterior end of the preserved skeleton and do not correspond to their actual position in the column. Dashed lines show three faults. Scale bar equals 50 cm. Modified from Delsett et al. 2016.
Fig 4.
Rostrum and vertebrae of Keilhauia nui (PMO 222.655).
Rostrum in A and B; dentaries in lateral view and premaxillae in ventral view. Scale bar equals 30 mm. Vertebra x18 (anterior dorsal) in C left lateral and D posterior views. Vertebra x39 (possible sacral) in E anterior view. Vertebra x29 (posterior dorsal) in F right lateral and G anterior views. Vertebra x54 (anterior caudal) in H anterior view. Vertebra x64 (caudal) in I lateral and J? anterior views. Vertebra x72 (fluke) in K anterior or posterior and L lateral views. Vertebrae numbers do not correspond to actual position in the vertebral column. Scale bar for C-L equals 20 mm. Abbreviations: dp diapophyses, dt dentary, na nasal, nc neural canal, pmx premaxilla, pp parapophyses, r rib.
Fig 5.
Vertebral dimensions of Keilhauia nui (PMO 222.655).
Vertebral numbers do not correspond to the actual position in the column, but to those used in the text. Blue area: dorsal region, orange area: preflexural area.
Fig 6.
Ratios of vertebral dimensions of Keilhauia nui (PMO 222.655) showing the relationship between height to length and height to width.
Vertebral numbers do not correspond to the actual position in the column, but to those used in the text. Blue area: dorsal region, orange area: preflexural area.
Fig 7.
Neural spine dimensions of Keilhauia nui (PMO 222.655) showing height and maximum anterior-posterior length.
Vertebrae numbers do not correspond to the actual position in the column, but to those used in the text. Blue area: dorsal region, orange area: preflexural area.
Fig 8.
Right pectoral girdle and humerus of Keilhauia nui PMO 222.655.
Scapula in A lateral and B medial views. Clavicle in C dorsal and D ventral views. Coracoid in E ventral view. Humerus in F dorsal, G ventral and H proximal views. Scale bar equals 20 mm. Abbreviations: amp anteromedial process, an anterior notch, ap acromion process, cf coracoid facet dp dorsal process, dpc deltopectoral crest, dt distal tip, gf glenoid facet, mp medial projection, pef preaxial accessory element facet, rf radial facet, rp rim on posterior side of medial projection, sf scapular facet, uf ulnar facet.
Fig 9.
Pelvic girdle and femur of Keilhauia nui (PMO 222.655).
Ilium in A and B lateral and medial (?) views. Posterior is to the left in A. The other ilium in C and D lateral (?) and medial (?) views. Posterior is to the right in C. Ischiopubis in E lateral or medial view. The better-preserved femur in F and G dorsal (?) and ventral (?) views. The other femur from the best preserved side in H dorsal or ventral view. Scale bar equals 20 mm. Abbreviations: ac acetabular end, d dorsal end, ff fibular facet, isch ischium, m medial end, p pubis, tf tibial facet.
Table 1.
Selected measurements of PMO 222.655, holotype specimen of Keilhauia nui. Lengths given in millimetres.
Fig 10.
Vertebral column of PMO 222.670 showing A, photograph of stratigraphically down side as preserved and prepared in the four jackets and B, illustration of the complete, restored, articulated series seen from the stratigraphic up side. Dashed line represents the edge of the cliff. Scale bar equals 50 cm. Modified from Delsett et al. 2016.
Fig 11.
Pelvic girdle and femora of PMO 222.670.
Ilium in A and B lateral (?) and medial (?) views. Posterior is to the right in A. The other ilium in C and D lateral (?) and medial (?) views. Posterior is to the right in C. Right ischiopubis in E ventral (anterior to the right) and F dorsal views. Left ischiopubis in G dorsal (anterior to the left) and H ventral views. Right femur in I dorsal (anterior to the right) and J ventral views. Left femur in K dorsal (anterior to the left), L ventral, M proximal and N distal views. Scale bar equals 20 mm. Abbreviations: ac acetabulum end, d dorsal end, dp dorsal process, ff fibular facet, isch ischium, m medial end, n notch in acetabular end, p pubis, tf tibial facet, vp ventral process, vr ventral ridge.
Table 2.
Selected measurements for PMO 222.670, Ophthalmosauridae indet.
Lengths are given in millimetres.
Fig 12.
Pelvic girdles and hind fin material.
Ilium of PMO 222.662 in A medial or lateral view. Posterior is to the right. Femur and fibula of PMO 222.662 in B dorsal, C ventral and D proximal views. Ischiopubis of PMO 222.662 in E dorsal and F ventral views. Ischiopubis of PMO 227.932 in G and H dorsal (?) and ventral (?) views. Dashed line shows where pieces are missing. Scale bar for A-G equals 20 mm. The Bauer (1898) specimen pelvic girdle in I, not to scale. Compare I to the right ilium of PMO 222.654 Janusaurus lundi holotype in J lateral view and the left ischiopubis of PMO 222.654 in K dorsal view. Scale bar for J-K equals 10 mm. Abbreviations: ac acetabular end, d dorsal end, dp dorsal process, f fibula, m medial end, vp ventral process, vr ventral ridge.
Fig 13.
a. Time calibrated phylogeny of non-ophthalmosaurid Ichthyopterygia showing the evolution of the pelvic girdle. Articulated pelvic girdles either redrawn from the literature or based on personal observation (see references in S1 Table). Green = ilium; yellow = pubis; red = ischium; orange = fused ischiopubis. Pelvic girdles shown at different scales. Topology following Ji et al. 2016, showing only those taxa with a preserved pelvis. Clade names represented by circled numbers; 1 = Ichthyopterygia, 2 = Ichthyosauria, 3 = Parvipelvia, 4 = Thunnosauria. b. Time calibrated phylogeny of Ophthalmosauridae showing the evolution of the pelvic girdle. Articulated pelvic girdles either redrawn from the literature or based on personal observation (see references in S1 Table). Green = ilium; yellow = pubis; red = ischium; orange = fused ischiopubis. Pelvic girdles shown at different scales. Relationships following the single tree recovered in the new analysis of the Roberts et al. 2014 matrix (Length = 132; CI = 0.455, RI = 0.6.) Bremer support values for Ophthalmosauridae ≥2 are shown below the branches.
Fig 14.
Keilhauia nui (PMO 222.655) represented by a triangle. Light blue = Early/Middle Jurassic specimens with a tripartite pelvis; Beige = Stenopterygius juvenile specimens; Black = Early/Middle Jurassic specimens with a bipartite pelvis; Dark blue = Late Jurassic specimens; Red = Cretaceous specimens. See S2 Table for specimens and references. The Slottsmøya specimens with long ischiopubis are shown in the red ellipse. A. Femur: humerus length plotted against age (Ma). There is a significant correlation (p = 1.55*10−5; r2 = 0.28 between the femur: humerus length and geological age. Orange line shows linear regression. B. Ilium: femur length plotted against age (Ma). There is no correlation (p = 0.25, r2 = 0.06). C. Ischiopubis: ilium length plotted against age (Ma). There is no correlation (p = 0.29, r2 = 0.07). D. Ischiopubis: femur length plotted against age (Ma). There is a weak correlation (p = 0.47*10−4, r2 = 0.07).