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FIGURE 10 in Geometric morphometric analysis of Protoconites minor from the Cambrian (Terreneuvian) Yanjiahe Formation in Three Gorges, South China

FIGURE 10. Protoconites minor from the Cambrian (Terreneuvian) Yanjiahe Formation showing morphological variance during the ontogeny. Size of these specimens increases from right to left and from top to bottom. 1. No. Y-596 (2)- 2; 2. No. Y-735A (20)-2; 3. No. Y-800A (19)-2; 4. No. Y-469B (5); 5. No. Y-581 (2); 6. No. Y-134 (10); 7. No. Y-523; 8. No. Y-1236 (2); 9. No. Y-29; 10. No. Y-617A (4)-3; 11. No. Y-558A (17); 12. No. Y-141A (19)-1; 13. No. Y-558A (33); 14. No. Y-617A (2); 15. No. Y-546A (2); 16. No. Y-732A (20); 17. No. Y-142A (8)-1; 18. No. Y-816A (4); 19. No. Y-1230A (45); 20. No. Y-425A (2); 21. No. Y-561A (5); 22. No. Y-567 (2); 23. No. Y-732A (32)-1; 24. No. Y-173A (4); 25. No. Y-1227A (10); 26. No. Y-51A (2); 27. No. Y-24B (2). "Y" means the locality of the fossils from Yangjiachong section.

FIGURE 7 in Geometric morphometric analysis of Protoconites minor from the Cambrian (Terreneuvian) Yanjiahe Formation in Three Gorges, South China

FIGURE 7. Morphospace of straight shell Protoconites minor generated by the Relative Warp (RW) analysis. 1. plot for RW 1–2; 2. plot for RW 1–3. All thin-plate splines correspond to the shapes of specimens in RW 1–2 and RW 1–3 planes, respectively.

FIGURE 6 in Geometric morphometric analysis of Protoconites minor from the Cambrian (Terreneuvian) Yanjiahe Formation in Three Gorges, South China

FIGURE 6. Protoconites minor morphospace generated by the Relative Warp (RW) analysis using mirrored specimens. 1. plot for RW 1–2; 2. plot for RW 1–3. All thin-plate splines correspond to points (indicated as a line) within the morphospace in RW 1–2 and RW 1–3 planes, respectively.

FIGURE 5 in Geometric morphometric analysis of Protoconites minor from the Cambrian (Terreneuvian) Yanjiahe Formation in Three Gorges, South China

FIGURE 5. Protoconites minor morphospace generated by the Relative Warp (RW) analysis using un-mirrored specimens with indication of characteristic thin-plate splines. 1. plot for RW 1–2; 2. plot for RW 1–3. Thin-plate splines show the shapes of specimens in RW 1–2 and RW 1–3 planes, respectively.

FIGURE 4 in Geometric morphometric analysis of Protoconites minor from the Cambrian (Terreneuvian) Yanjiahe Formation in Three Gorges, South China

FIGURE 4. Histogram showing the size spectra of Protoconites minor. 1. size distribution of all specimens analyzed in this study; 2. size distribution without laterally bended specimens.

FIGURE 2 in Geometric morphometric analysis of Protoconites minor from the Cambrian (Terreneuvian) Yanjiahe Formation in Three Gorges, South China

FIGURE 2. Protoconites minor from the Cambrian (Terreneuvian) Yanjiahe Formation in Yichang, Hubei, China. 1. No. Y-24B (2); 2. No. Y-41A (5)-1; 3. No. Y-765A (3); 4. No. Y-127B (1); 5. No. Y-28 (2); 6. No. CH-179A (3); 7. No. Y-273A (1); 8. No. Y-41A (14); 9. No. Y-445 (2); 10. No. Y-494 (2)-2; 11. No. Y-40A (11); 12. No. Y-1234 (3); 13. No. Y-844A (2); 14. No. Y-785 (2); 15. No. Y-40B (9)-1; 16. No. Y-880 (6); 17. No. Y-596 (2)-1; 18. No. Y-531 (3)-2. "CH" means the locality of the fossils from Dingjiaping section, "Y" means the locality of the fossils from Yangjiachong section.

FIGURE 3 in Geometric morphometric analysis of Protoconites minor from the Cambrian (Terreneuvian) Yanjiahe Formation in Three Gorges, South China

FIGURE 3. Definition of landmarks and semi-landmarks and the result of superimposition. 1. and 2. landmarks and semi-landmarks set on both straight and laterally bent specimens. Type II landmarks are 1, 2, and 3, and sliding semilandmarks are 4–34 in 1. and 2.; 3. consensus configuration after superimposition using Generalized Procrustes Analysis.

FIGURE 1 in Geometric morphometric analysis of Protoconites minor from the Cambrian (Terreneuvian) Yanjiahe Formation in Three Gorges, South China

FIGURE 1. Locality and stratigraphy of the Cambrian (Terreneuvian) Yanjiahe Formation in Yichang, Hubei Province, China. 1. Sketch map of the People's Republic of China, showing the position of the collecting locality in Hubei Province; 2. Simplified geological sketch map of the Three Gorges area, Hubei Province, South China, showing the outcrops of Cambrian strata. Red boxes around 3 (Yanjiahe area) and 4 (Dingjiaping area) denote areas that are enlarged for additional detail; 3. Detailed geological sketch map of the Yanjiahe area, showing the outcrops of the Yanjiahe Formation; 4. Detailed geological sketch map of the Dingjiaping area, showing the outcrops of the Yanjiahe Formation. (In 3 and 4 map: White = Ediacaran Dengying Formation; Pink and light green = Cambrian Yanjiahe Formation; Yellow and light blue = the Cambrian Shuijingtuo Formation; Green = Cambrian Shipai Formation; Black triangles indicate locations of measured stratigraphic sections) 5. Stratigraphic sequence of Lower Cambrian strata in the Gunziao section, Three Gorge area, indicating the horizons where fossils were collected.

opencc-by-4.0Mar 2022View details →

Fig. 2 in A new Cambrian catillicephalid trilobite from the Shallow Bay Formation of western Newfoundland, Canada

Fig. 2. Cranidia of catillicephalid trilobite Catillicephala cifellii sp. nov. from the Downes Point Member, Shallow Bay Formation, Guzhangian, Miaolingian, Cambrian; boulders BPS 468 (A), BPS 467 (B, D), BPS 458 (C), Broom Point South, western Newfoundland, Canada. A. GSC 142516, paratype; dorsal (A1), lateral (A2), and anterior (A3) views. B. GSC 142517, paratype; anterior (B1), lateral (B2), and dorsal (B3) views. C. GSC 142518, paratype; dorsal (C1), anterior (C2), and lateral (C3) views. D. GSC 142519, paratype; dorsal view. Scale bars 1 mm.

Fig. 9 in Muscle attachment scars in helcionelloids from Denmark cast light on mollusc evolution in the Cambrian

Fig. 9. Muscle scars on internal mould of the rostroconch Ribeiria Sharpe, 1853, in lateral view. Both the anterior and posterior median muscle scars lie across the median dorsal plane of symmetry, the former attached to the transverse pegma preserved as a deep cleft on the internal mould. The posterior scar is a uniform attachment area, often ornamented with transverse growth lines, unlike the multiple small scars of Eotebenna (based on Pojeta and Runnegar 1976; Polechova 2015).

Fig. 7 in Muscle attachment scars in helcionelloids from Denmark cast light on mollusc evolution in the Cambrian

Fig. 7. Muscle scars on internal moulds of Palaeozoic bivalves. A. Left valve of Babinka Barrande, 1881, from the Lower Ordovician of Öland, Sweden (after Soot-Ryen 1969, length of specimen about 20 mm). B. Left valve of Palaeoneilo musculosa (Knod, 1908) from the Devonian of Bolivia (after Babin and Farjat 1994, length of specimens about 20 mm). C, D. Sketches in apical view showing asymmetry between pedal muscle scars (black) on internal molds of Palaeoneilo musculosa between left and right valves, and variation in pattern of pedal muscle between specimens (after Babin and Farjat 1994). Abbreviation: am, anterior adductor muscle scar.

Fig. 8 in Muscle attachment scars in helcionelloids from Denmark cast light on mollusc evolution in the Cambrian

Fig. 8. Muscle scars on internal moulds of helcionelloids. All sketches oriented in lateral view with the apex to the right. A. Vendrascospira frykmani Peel and Kouchinsky, 2022 (after Peel 2023). B. Anhuiconus microtuberus Zhou and Xiao, 1984 (after Parkhaev 2002). C. Hensoniconus siku (Peel and Kouchinsky, 2022) (after Peel 2023). D. Bemella communis Parkhaev, 2001 showing three pairs of muscle scars (black, after Parkhaev 2014b); Li et al. 2021) considered the two pairs of scars on the supra-apical surface (joined by grey) to be traces of a single pair of scars. E. Yochelcionella (based on outline of Yochelcionella ostentata Runnegar and Jell, 1974) showing pair of apical muscle scars described by Vendrasco et al. (2010) in Yochelcionella snorkorum Vendrasco, Porter, Kouchinsky, Li, and Fernandez, 2010. F. Eotebenna danica sp. nov., with multiple scars forming a muscle attachment area at the apex.

Fig. 6 in Muscle attachment scars in helcionelloids from Denmark cast light on mollusc evolution in the Cambrian

Fig. 6. Surface textures on internal mould of a helcionelloid mollusc Vendrascospira frykmani Peel and Kouchinsky, 2022, PMU 39208 from GGU sample 271492, Henson Gletscher Formation, Løndal, Peary Land, North Greenland, Miaolingian, middle Cambrian. A1. Lateral view with one muscle attachment scar from each of the two pairs of muscle scars (arrows). A2. Dorsal view showing pair of symmetrically placed muscle scars (arrows) on the supra-apical surface (right side of A1). The muscle scars lie on each side of the median area with botryoidal surface texture. A3. Detail of muscle scar (left scar in A1). A4. Detail of finely imbricate shell structure from the median area of A2.

Fig. 3. Helcionelloid mollusc Eotebenna viviannae Peel, 1991a in Muscle attachment scars in helcionelloids from Denmark cast light on mollusc evolution in the Cambrian

Fig. 3. Helcionelloid mollusc Eotebenna viviannae Peel, 1991a, internal moulds, Andrarum Limestone, Bornholm, Denmark, Guzhangian, Miaolingian, middle Cambrian. A. MGUH 19565, paratype, lateral view (A1) with detail of apex (A2). B. MGUH 34273, lateral (B1) and apico-lateral views showing impression of comarginal ornamentation and cylindrical form of median sub-apical area (B2). C. Specimen lost, lateral view (C1) with detail of apex (C2), arrow locates detail of shell structure (C3). D. MGUH 34274, lateral view with detail of radial fibrous structure and overlying imbricated lamellae (D2), and patch of ornamented outer shell (D1, arrow). E. MGUH 34275, lateral view with detail of apex (E2) with muscle scars; arrows locate possible muscle scar. F. MGUH 34276, lateral view (F1) with detail of possible muscle scar (F2) located by arrows.

Fig. 2. Helcionelloid mollusc Eotebenna viviannae Peel, 1991a, MGUH 19564 in Muscle attachment scars in helcionelloids from Denmark cast light on mollusc evolution in the Cambrian

Fig. 2. Helcionelloid mollusc Eotebenna viviannae Peel, 1991a, MGUH 19564, holotype, internal mould, Andrarum Limestone, Bornholm, Denmark, Guzhangian, Miaolingian, middle Cambrian. A1. Oblique lateral view showing margin of shell (arrow) along the narrow slit joining the sub-apical and supra-apical apertures. A2. Oblique apico-lateral view. A3. Lateral view. A4. Oblique view showing inverted teardrop-shaped sub-apical aperture and irregular area (arrow) of possible muscle scar. A5. Lateral view of apex. A6. Oblique lateral view of apex showing radial fibrous structure beneath smooth outer layer.

Fig. 1. Geological and geographical background. A in Muscle attachment scars in helcionelloids from Denmark cast light on mollusc evolution in the Cambrian

Fig. 1. Geological and geographical background. A. Cambrian stratigraphy of southern Bornholm, Denmark (based on Nielsen and Schovsbo 2007). B. Map of the Baltic area showing location of Bornholm, with location of studied locality (asterisk) on the rivulet Øleå (C), and the Lake Vänern area in southern Sweden (D), with collection locality on the western slopes of the hill Kinnekulle (asterisk).

Fig. 4 in Muscle attachment scars in helcionelloids from Denmark cast light on mollusc evolution in the Cambrian

Fig. 4. Helcionelloid mollusc Eotebenna danica sp. nov., internal moulds, Andrarum Limestone, Bornholm, Denmark, Guzhangian, Miaolingian, middle Cambrian. A. MGUH 34277, lateral view (A1) with rectangles indicating location of Fig. 5B1, B2, and B3. Muscle scars at apex illustrated in different orientations (A2–A6), with arrow in A2 indicating slight diagenetic compression or deformation along edge of muscle field. Arrow in A3 indicating imbricated lamellar structure shown in detail in A4. B. MGUH 34278, apex in lateral view. C. MGUH 34279, lateral view. D. MGUH 34280, holotype, lateral (D1) and apico-lateral (D2) views, the latter showing the laterally compressed shell form, with detail of apical muscle scars (D3). E. MGUH 34281, lateral view. F. MGUH 34282, apex in lateral view. pontifex Runnegar and Jell, 1976, from the Currant Bush southern Freuchen Land, North Greenland is more strongly Limestone (Miaolingian) of Queensland, Australia, is also coiled than Eotebenna danica, with a convex supra-apical much more elongate than Eotebenna danica but the massive surface, in lateral view, and the apex strongly overhanging snorkel is circular in cross-section compared to the inverted the sub-apical surface (Peel 1989, 1991b). teardrop-shape in the two Bornholm species. Eotebenna arctica Peel, 1989, from the Henson Gletscher Stratigraphic and geographic range.—Drumian of Sweden Formation (uppermost Series 2, Stage 4, lower Cambrian) of and Guzhangian of Denmark (both middle Cambrian).

Fig. 5 in Muscle attachment scars in helcionelloids from Denmark cast light on mollusc evolution in the Cambrian

Fig. 5. Helcionelloid mollusc Eotebenna danica sp. nov. from Miaolingian, middle Cambrian A. MGUH 34283, internal mould with traces of comarginal ornamentation and rugae (arrow), western slopes of Kinnekulle, southern Sweden, Drumian. B. MGUH 34277, details of shell structure, Andrarum Limestone, Bornholm, Denmark, Guzhangian (general view of the specimen in Fig. 4A). Surface of internal mould (B1) digitally inverted and mirrored here (B2) to depict shell structure on the interior surface of the shell. Detail of imbricate lamellae on internal mould (B3).

opencc-by-4.0Feb 2023View details →

Fig. 8 in New palaeoscolecid plates from the Cambrian Stage 3 of northern Mongolia

Fig. 8. Two conical fossils regarded as palaeoscolecid fragments from Khuhtolgoi section, northern Mongolia, Cambrian Stage 3. A. NRM X11556 in latero-abapical (A1) and latero-apical (A2) views, with a close-up on button-shaped elements (A3). B. NRM X11556 in latero-apical (B1, B2) views, with a close-up on button-shaped elements (B3).