Fig. 51 in Early-middle Cambrian stratigraphy and faunas from northern Siberia

Fig. 51. Phosphatised hyolith opercula from the lower Cambrian Sekten Formation, lower reaches of the Lena River (A–D) and Erkeket Formation, Khorbusuonka River (E–H), Siberia, Russia; samples 19/10.25 (E, H), 19/11.75 (F, G), and 22/50 (A–D). A, B. Parkula bounites Bengtson in Bengtson et al., 1990, SMNH X11207 and 11208, respectively. C, D. Hyolithid operculum 1, SMNH X11209 and X11210, respectively. E, H. Triplicatella sp., SMNH X11211 and X11212, respectively. F. Majatheca tumefacta Missarzhevsky in Rozanov et al., 1969, SMNH X11213. G. Triplicatella papilio Kouchinsky in Kouchinsky et al., 2015, SMNH X11214. A1, D2, inner surface; B1, C1, E3, H2, outer surface; A2, oblique lateral; B2, C2, D1, E1, H1, lateral; C3, E2, dorsal; and A3, C4, ventral views. Scale bar 500 µm.