Cryptoporocyathidae Zhuravleva, 1960

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

Family Cryptoporocyathidae Zhuravleva, 1960 Genus Cryptoporocyathus Zhuravleva, 1960

Type species: Cryptoporocyathus junicanensis Zhuravleva, 1960 ; Medvezh’ya Formation , Tommotian stage (correlated with the upper part of Cambrian Stage 2); Moyero River, Siberian Platform, Russia .

Cryptoporocyathus junicanensis Zhuravleva, 1960 Fig. 79B .

Material. —Three phosphatised fragments, including SMNH Sp11538, from sample 21/21, Tyuser Formation, Lena River, Siberia, Russia. Dokodocyathus regularis Zone, Tommotian stage (correlated with the upper part of Cambrian Stage 2).

Description. —Phosphatic crusts replicating wall fragments penetrated by evenly distributed pores of two distinct sizes. Larger pores are elliptical in vertical direction, up to 200 × 100 µm in diameters. Smaller pores are rounded or elongated, up to 40 µm long and 20 µm wide. Inner ( Fig. 79B 1 ) and outer ( Fig. 79B 2 ) surfaces of the wall are similar. Traces of septa or tabula attachment are not observed.

Remarks.—The only archaeocyath possessing an outer wall with such a type of the porosity and lacking any intervallar elements on the entire Siberian Platform is Cryptoporocyathus junicanensis Zhuravleva, 1960 , belonging to single chambered capsulocyathines ( Zhuravleva 1960; Debrenne et al. 2015). A similar form occurring in the Tommotian and lowermost Atdabanian strata but studied in thin sections only, Korshunovicyathus melnikovi ( Korshunov and Zhuravleva, 1967) is characterised by an attached microporous sheath on the outer wall, rather than smaller pores situated between larger ones (Debrenne et al. 2015).

A similar wall fragment, SMNH Sp11539 ( Fig. 79E ), from sample 15/23 is found in the Chuskuna Formation, upper Kessyusa Group, at the Khorbusuonka River, beds attributed to the Watsonella Zone, Cambrian Stage 2. The fragment shows irregularly distributed rounded and elliptical pores, up to 70 µm across, smaller in diameter than those in Cryptoporocyathus junicanensis fragments from sample 21/21. They are surrounded by a pustulose structures with smaller pores. Archaeocyath fragments from the upper 10–12 m of the Kessyusa Group were previously reported without illustration by Missarzhevsky (1989) and Astashkin et al. (1991: 70) (see Kouchinsky et al. 2012: SOM, appendix 1).

Stratigraphic and geographic range.—Cambrian Stage 2, Siberia, Russia.

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).

Fig. 1. Locality maps. A. Map of the Siberian Platform. B. Khorbusuonka River. Localities referred to in the main text: 96-1, 96-2, 96-3, Malaya Kuonamka (MK) and 96-6, 96-7, 96-8, Bol’shaya Kuonamka (BK) rivers, eastern flank of the Anabar Uplift; 3, 11, 15, 19, 20, Khorbusuonka River, Olenyok Uplift; 21, 22, Lena River lower reaches, Ulakhan-Ald’yarkhay Brook; Le, Lena River middle reaches, Tiktirikteekh and Bydyangaya Brooks; Al, Aldan River, between sections “Dvortsy” and Ulakhan- Sulugur. Margin of the Siberian Platform is shown by a dashed line in A.

Fig. 2. Stratigraphic columns of sections 96-1 and 96-2, Malaya Kuonamka River and section 96-8, Bol’shaya Kuonamka River, Siberia, Russia (after Kouchinsky et al. 2011: fig. 2). Arrows with numbers indicate derivation of fossiliferous samples. Botoman Stage is correlated herein with the Cambrian Stage 4, in accordance with Geyer (2019).Asterisk A, indicates occurrences of Davidonia anabarica, Enigmaconus? pyramidalis, Pelagiella sp. 1 and 2, Majatheca tumefacta, Tetratheca clinisepta, “Lenatheca groenlandica”, Conotheca cf.mammilata, Parkula cf. esmeraldina (see Kouchinsky et al.2015a). Asterisk B, indicates occurrences of Anabaroconus sibiricus, Eotebenna viviannae, Kuonamkaella oliva, Leptostega cf. hyperborea, Pelagiella sp. cf. Cambretina mareki, Pelagiella sp. cf. Costipelagiella zazvorkai, Pojetaia dentifera, Protowenella sp., Pseudomyona queenslandica, and Yochelcionella angustiplicata (see Gubanov et al. 2004b and Kouchinsky et al. 2011). Abbreviations: Ac., Acadoparadoxides; An., Anabaraspis; B., Bergeroniellus expansus; P., Paramicmacca; Fm., Formation; H., Homotreta; O-S, Ovatoryctocara–Schistocephalus; T., Triplagnostus.