Hadimopanella spp.

Kouchinsky, Artem, Alexander, Ruaridh, Bengtson, Stefan, Bowyer, Fred, Clausen, Sébastien, Holmer, Lars E., Kolesnikov, Kirill A., Korovnikov, Igor V., Pavlov, Vladimir, Skovsted, Christian B., Ushatinskaya, Galina, Wood, Rachel & Zhuravlev, Andrey Y., 2022, Early-middle Cambrian stratigraphy and faunas from northern Siberia, Acta Palaeontologica Polonica 67 (2), pp. 341-464 : 421

Hadimopanella spp.

Fig. 59 .

Material.—Several hundred calcium phosphate sclerites, including SMNH X11269–11292, from samples 19/26.75, 19/31.75, 19/33, 19/40, 19/43.25, 19/46.5, 19/55, 20/5B, 20/6B, Erkeket Formation, Toyonian–Amgan stages (correlated with the Cambrian Stage 4–Wuliuan Stage), 19/65.5, 19/66.5 from the Kuonamka Formation and 19/70.5 from the Yunkyulyabit-Yuryakh Formation, lower Mayan Stage (correlated with the lower Drumian Stage). Khorbusuonka River, Siberia, Russia.

Description.—Disk-like, 100–250 μm in diameter, almost circular or ovaliform sclerites with a gently convex smooth lower side and the upper side representing the conical surface capped with a nodular face with nodes 10–15 μm in diameter. The nodular face with an oval outline ornamented by up to 40 tightly arranged nodes ( Fig. 59A–E ) or having a circular outline ornamented by up to 30 tightly arranged nodes ( Fig. 59J–R, T, U, X ). In some of the sclerites a circlet of nodes surrounds a central group of 1–4 nodes ( Fig. 59K, L, T, X ). Conical surface carries a marginal rim with concentric zones (see Fig. 59A–D ) and short radial plication with faint radial folds and furrows in the periphery (see Fig. 59J–L, N, V ) as well as covered with fine granulation ( Fig. 59T–V ). Marginal zone of sclerite can be very narrow in some forms ( Fig. 59O–R ). Conical surface can be displaced, with nodes inclined in the same direction ( Fig. 59G–I, S, W ).

Figures

Fig. 59. Paleoscolecids Hadimopanella spp. from the Cambrian Erkeket (A–L, N–X) and Yunkyulyabit-Yuryakh (M) formations, Khorbusuonka River, Siberia, Russia; samples 19/31.75 (B, H–K, N, P–W), 19/43.25 (A, E–G, L, O), 19/70.5 (M), 20/5B (C, X), and 20/6B (D). A–X. Disarticulated sclerites, SMNH X11269–11292, respectively.A–D, F, G1, L, M2, S–V, X, apical; E, G2, K, M1, N–P, R, W2, oblique apical; Q, oblique basal; and W1, lateral views. Scale bar 100 µm.