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.图6 采自北格陵兰佩里地兰隆达尔地区亨森冰川组GGU样品271492的Vendrascospira frykmani Peel & Kouchinsky, 2022（海伦尼螺类软体动物，helcionelloid mollusc）内模的表面纹理，标本编号PMU 39208，时代为中寒武统米陵统（Miaolingian）。 A1 侧视图，示两对肌痕各一枚肌附着痕（箭头指示）。 A2 背视图，显示顶锥上方表面（对应A1右侧）一对对称分布的肌痕（箭头指示）；该肌痕位于具葡萄状表面纹理的中域两侧。 A3 肌痕细节图（对应A1左侧肌痕）。 A4 A2中域的细密覆瓦状壳层结构细节图。