Davidonia anabarica ( Parkhaev, 2005 )

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 : 375-377

Davidonia anabarica ( Parkhaev, 2005)

Fig. 24A, B .

Material.—Several hundred calcium phosphatic internal moulds, including figured specimen SMNH Mo194701 and 194702, from samples 19/11.75 and 19/12.75, lower Botoman stage (correlated with the lower part of Cambrian Stage 4), Erkeket Formation, Khorbusuonka River. Additional material attributed to Davidonia cf. anabarica represents two internal moulds, from samples 19/31.75 and 19/33, Toyonian stage (correlated with the Cambrian Stage 4), Erkeket Formation, Khorbusuonka River and several internal moulds from sample 22/67, Sekten Formation, lower Lena River, Kounamkites Zone, Amgan stage (correlated with the Wuliuan Stage). Siberia, Russia.

Remarks.—The fossils are identical to those from the lower part of the Botoman stage, eastern flanks of the Anabar Uplift described by Kouchinsky et al. (2015a). As pointed out by Kouchinsky et al. (2015a: 430), Davidonia anabarica has tuberculated internal moulds, otherwise similar to Davidonia rostrata . The latter is reported from the Cambrian Stages 3–4 and lower Wuliuan Stage and occurs in Gondwana (Bengtson et al. 1990; Wotte 2006; Claybourn et al. 2019; Li et al. 2019) and Laurentia ( Skovsted 2004).

Stratigraphic and geographic range.— Lower Botoman stage (correlated with the lower part of Cambrian Stage 4), Siberian Platform.

Genus Bemella Missarzhevsky in Rozanov et al., 1969

Type species: Helcionella jacutica Missarzhevsky in Rozanov and Missarzhevsky, 1966; Dokidocyathus regularis Zone, Tommotian stage ; Tiktirikteekh, near Churan village, middle Lena River, Siberia, Russia.

Figures

Fig. 24. Molluscs from the lower Cambrian Erkeket Formation, Khorbusuonka River (A–F, J–N) and Sekten Formation, lower reaches of the Lena River (G–I), Siberia, Russia; samples 11/2B (E, F, J), 11/16.1 (K, M, N), 19/12.75 (A), 19/11.75 (B), 20/1B (L, O, P), 20/6B (C, D), and 22/50 (G–I). A, B. Davidonia anabarica (Parkhaev, 2005), internal moulds, SMNH Mo194701 and 194702, respectively. C. Mellopegma sp., internal mould, SMNH Mo194713. D. Stenotheca cf. drepanoida (He and Pei in He et al., 1984), silicified shell, SMNH Mo194714. D1, lateral view; D2, oblique apertural view. →