Figures & data
Figure 1. A, Hyolithid in lateral view. B, Orthothecid in lateral view. C, Protowenella with operculum in place reconstructed as an orthothecid hyolith. D–F, Alternative reconstructions of Protowenella; D, as an exogastric monoplacophoran (Runnegar & Jell Citation1976); E, as an endogastric helcionelloid (Peel Citation1991a, b); F, as a gastropod. Inferred digestive tract shown schematically with mouth (black dot) and anus (×).
Figure 2. Locality and geological information. A, Lauge Koch Land – Løndal region of North Greenland showing collection site of GGU samples 218831 and 271492. B, Greenland, with arrow indicating location of A. C, Løndal region of Western Peary Land (see inset in A) showing collection locality for GGU sample 271718. D, Cambrian stratigraphic nomenclature of the Lauge Koch Land – Løndal region showing derivation of GGU samples from the Henson Gletscher Formation (black dot).
Figure 3. Protowenella flemingi Runnegar & Jell, Citation1976, internal moulds from the Henson Gletscher Formation, North Greenland, Cambrian, Miaolingian Series, Wuliuan Stage, Ptychagnostus gibbus Biozone. A, B, D, G, I, PMU 38329 from GGU sample 218831, Lauge Koch Land. A, B, apertural views showing isostrophic form and bilaterally symmetrical operculum. D, detail of umbilical area showing pits representing the cardinal processes (car) and clavicles (clav). G, I, oblique apertural views. C, E, PMU 38330 from GGU sample 271718 in oblique lateral and lateral views, with arrow in E showing termination of circumbilical channel prior to the broken aperture. F, PMU 38331 from GGU sample 271718, apertural view. H, PMU 38332, apertural view. Scale bars: 50 µm (A, B, D, G, I), 100 µm (C, E, F, H).
Figure 4. Protowenella flemingi Runnegar & Jell, Citation1976, PMU 38333 from GGU sample 271492, largely exfoliated internal mould, Henson Gletscher Formation, North Greenland, Cambrian, Miaolingian Series, Wuliuan Stage, Ptychagnpstus gibbus Biozone. A, oblique apertural view with channel on internal mould (arrow). B, oblique lateral view showing apertural margin lacking emargination corresponding to the circumbilical channel on the internal mould. C, oblique lateral view showing growth lines (arrow) near apertural margin. Scale bar 100 µm.
Figure 5. Hyolith opercula, Cambrian Series 2 (Stage 4), North Greenland. A, PMU 22963, Buen Formation, internal surface of hyolithid operculum showing cardinal processes and clavicles. B, PMU 22969, Buen Formation, external surface of hyolithid Kalaallitia myliuserichseni Peel & Willman, Citation2018 showing cardinal and conical shields. C, Conotheca? sp., PMU 36944, Aftenstjernesø Formation. showing internal surface with cardinal processes and clavicles set in clavicular ridge. D, H, Conotheca laurentiensis Landing & Bartowski, Citation1996, PMU 36952, Aftenstjernesø Formation, oblique views showing flat external surface with protoconch (arrow in D), and clavicle and cardinal processes (H). E, Parkula bounites Bengtson in Bengtson et al., Citation1990, PMU 36931, Aftenstjernesø Formation, external surface. F, Conotheca? sp., PMU 36947, Aftenstjernesø Formation, showing internal surface with cardinal processes and clavicles set in clavicular ridge. G, PMU 22968, Buen Formation, internal surface of hyolithid Kalaallitia myliuserichseni. Scale bars: 100 µm (C–F, H), 1 mm (A, B, G).
