Carinacyathus sp.

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 : 450

Carinacyathus sp.

Fig. 79D .

Material. —A single phosphatised fragment, SMNH Sp11542, from sample 20/1B, Erkeket Formation, Khorbusuonka River, Siberia, Russia. Lower Botoman stage (correlated with the lower part of Cambrian Stage 4).

Remarks.—Phosphatic crust replicating a fragment of a thick cup wall with geniculate tubular canals, elliptical in cross-section and 30–50 µm across. Among forms of archaeocyaths described from the lower Botoman part of the Erkeket Formation, tubular noncommunicating (lacking lateral pores) canals from the inner wall are known only from Carinacyathus , while other genera are characterised either by simple inner walls or flattened and S-shaped in vertical section scales. From investigation of Carinacyathus cups in thin sections, it was suggested that all of the species have the inner wall with downwardly projecting, straight canals, connected to the central cavity by supplementary structures, bracts (Debrenne et al. 2015). The new material indicates that the inner wall is pierced by geniculate (V-shaped in longitudinal section) canals without bracts.

Figures

Fig. 79. Archaeocyatha, phosphatized fragments from the lower Cambrian Erkeket (A, D, H, I) and Chuskuna (E) formations, Khorbusuonka River and Tyuser Formation, lower reaches of the Lena River (B, C, F, G), Siberia, Russia; samples 15/23 (E), 20/1B (A, D, H, I), and 21/21 (B, C, F, G). A, H, I. Ajacicyathina family, gen. and sp. indet., fragments of cups with simple rounded pores, SMNH Sp11535–11537, respectively. A1, H1, lateral view; A2, basal view; H2, oblique lateral view showing inner part of the cup. B, E. Cryptoporocyathus junicanensis Zhuravleva, 1960. B. Wall fragments, SMNH Sp11538–11539, respectively. B1, inner surface of the wall. B2, outer surface of the wall. E. Wall fragment, SMNH Sp11540. C. Dictyocyathus sp., fragment of an intervallar dictyonal network, SMNH Sp11541. D. Carinacyathus sp., fragment of a cup wall with geniculate tubular canals, SMNH Sp11542. F. Cambrocyathellus sp., fragment of a cup, SMNH Sp11543. G. Possible archaeocyath pelta (upper covering structure of the cup), SMNH Sp11544. Scale bar: 1.25 mm (C), 500 µm (B, F–I), and 250 µm (A, D, E).