Olenekotreta, Ushatinskaya, 2016

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 : 368

Olenekotreta olenekensis ( Ushatinskaya, 1997)

Fig. 17 .

Material.—Ten calcium phosphatic dorsal and ventral valves and apical fragments, including figured SMNH Br151259– 151264, from sample 8/17.6, Kuonamka Formation, Bol’shaya

Kuonamka River, Siberia, Russia. Kounamkites Zone, Amgan stage (correlated with the Wuliuan Stage).

Description.—Fragmentary ventral and dorsal valves, up to 2 mm wide, with the outer surface ornamented with concentric wavy growth lines superimposed with radially oriented plication. Ventral valve convex, with apex overhanging posteriorly, pseudointerarea orthocline with an open broad subtriangular delthyrium. Dorsal valve gently convex with straight posterior part and wide notothyrium. Brephic shell, 400–450 µm wide and 250–350 µm long, with numerous flattened tubercles ca. 5 µm in diameter. Brephic ventral valve with a single bulge at the apex and a pair of lateral bulges anteriorly. Brephic dorsal valve with a single bulge at the apex and two pairs of bulges in the middle and anterior parts.

Remarks.—See description and comparison by Ushatinskaya (1997, 2016).

Stratigraphic and geographic range.—Amgan and Mayan stages (correlated with the Wuliuan–Guzhangian stages), Siberian Platform.

Figures

Fig. 17. Paterinid brachiopod Olenekotreta olenekensis Ushatinskaya, 1997 from the middle Cambrian Kuonamka Formation, Bol’shaya Kuonamka River, Siberia, Russia; sample 8/17.6.A, C, E. Ventral valves, SMNH Br151259–151261, respectively.B, D, F. Dorsal valves, SMNH Br151262–151264, respectively. Scale bar: 500 µm (A–D) and 250 µm (E, F).