Loculitheca, Sysoev, 1968

Kouchinsky, Artem, Bengtson, Stefan, Clausen, Sébastien & Vendrasco, Michael J., 2015, An early Cambrian fauna of skeletal fossils from the Emyaksin Formation, northern Siberia, Acta Palaeontologica Polonica 60 (2), pp. 421-512 : 445-447

Loculitheca ? sp.

Fig. 25D .

Material.—Several tens of fragments of phosphatised internal moulds, including SMNH X 4634, from sample 7/36.7. Emyaksin Formation, Bol’shaya Kuonamka; correlated with the Delgadella anabara Zone, Atdabanian Stage.

Remarks.—The moulds are straight, 1–2 mm long, slightly diverging (<5º) and covered with faint thin transversal growth lines. Oval septae with straight margins are perpendicular to the wall and concave towards the conch aperture. The fossils are most similar morphologically to Loculitheca Sysoev, 1968 . Turcutheca Missarzhevsky in Rozanov et al., 1969 and Ovalitheca Sysoev, 1968 are also similar but have laterally curved conchs; no such curvature is recognised in the fragments available.

Figures

Fig. 25. Hyolith conchs from lower Cambrian Emyaksin Formation, Bol’shaya Kuonamka River, Anabar Uplift, Siberia; sample 7/36.7. A. Hyolithida sp. indet. 1, SMNH X 4656; lateral (A1), dorsal (A2), and apertural (A3) views. B. “Lenatheca groenlandica (Poulsen, 1932)”?, initial part, SMNH X 4640; apertural (B1), dorsal (B2), and lateral (B3) views. C. Microcornus? sp., SMNH X 4655; lateral (C1), apertural (C2), and dorsal (C3) views. D. Loculitheca? sp., SMNH X 4634; D1, oblique apical view, septum; D2, plan view of the conch. E–G. Conotheca cf. C. mammilata Missarzhevsky in Rozanov et al., 1969. E. SMNH X 4625; lateral view. F. SMNH X 4626; dorsal view. G. SMNH X 4627; lateral view. Scale bar 600 μm.