Cupitheca sp.

Kouchinsky, Artem, Bengtson, Stefan, Landing, Ed, Steiner, Michael, Vendrasco, Michael & Ziegler, Karen, 2017, Terreneuvian stratigraphy and faunas from the Anabar Uplift, Siberia, Acta Palaeontologica Polonica 62 (2), pp. 311-440 : 391

Cupitheca sp.

Fig. 51K.

Material.—Two internal moulds, including figured SMNH X5859,from sample5a/17.5(section96-5a, Fig.2 ),Emyaksin Formation, eastern Anabar Uplift, Siberian Platform, Russia. Correlated with lower part of Cambrian Stage 2.

Remarks.—The fossils are represented by fragments of internal moulds with longitudinal striation, broadly oval to nearly circular cross-section, and hemispherical narrower end formed by a septum. They are most similar to Actinotheca mira (He in Qian, 1977) from the middle Meishucunian Stage of South China (see discussion of the genera Actinotheca Xiao and Zhou, 1984 and Cupitheca by Bengtson et al. 1990: 203; Gravestock et al. 2001: 97), but have a less prominent blunt termination. Cupitheca mira is also reported from the Tommotian and Atdabanian stages of the Siberian Platform (Parkhaev and Demidenko 2010: 951). Cupitheca sp. is herein interpreted as an orthothecid hyolith with a hemispherical, apically convex septum. A similar fragment of an internal mould, albeit with an oval and less prominent terminal septum, was illustrated by Kouchinsky et al. (2015a: fig. 25D) as Loculitheca ? sp. from the Atdabanian beds of the Emyaksin Formation (section 96-7 therein).

Figures

Fig. 2. Composite δ13Ccurve for the Bol’shaya Kuonamka River sections 96-4, 5, and 5a and sampled horizons with fossiliferous samples (arrows with carb numbers). Arrow 4/4 indicates “marker bed with angustiochreids” (Val’kov 1975; Kouchinsky et al. 1999). For section 96-6 see Kouchinsky et al. (2001, 2015a). Shift in stratigraphic column at Manykay–Emyaksin formations contact indicates position of sequence boundary. Stratigraphic ranges and first appearances of fossils (see SOM 1): 1, first appearance of helcionellid molluscs; 2, Oelandiella korobkovi; 3, Securiconus cf. simus; 6, Obtusoconus vostokovae; 7, Obtusoconus cf. mirabilis; 8, Anabarella plana; 13, Aldanella attleborensis; 14, Aldanella cf. sibirica; 22, Purella antiqua; 24, Yunnanopleura accurata; 34, Lopochites sp.; 35, Tianzhushania longa; 37, first appearance of Halkieria sp.; 38, Chancelloria symmetrica; 42, Khetatheca cotuiensis; 44, Conotheca cf. mammilata; 46, Turcutheca sp.; 47, Cupitheca sp.; 50, Orthothecid operculum type C; 51, Protohertzina anabarica; 52, Fomitchella infundibuliformis; 53, Fomitchella aff. infundibuliformis; 54, Fomitchella acinaciformis; 55, Fomitchella aff. acinaciformis; 56, Hyolithellus vladimirovae; 57, Hyolithellus sp.; 60, Selindeochrea cf. tecta; 61, Selindeochrea tripartita; 62, Selindeochrea missarzhevskyi; 63, Selindeochrea ternaria; 64, Anabarites trisulcatus; 65, Anabarites latus; 66, Anabarites natellus; 67, Anabarites kelleri; 68, Anabarites biplicatus; 69, Anabarites tristichus; 70, Anabarites compositus; 71, Anabarites hexasulcatus; 72, Anabarites hariolus; 73, Aculeochrea rugosa; 74, Tiksitheca licis; 75, Cambrotubulus decurvatus; 76, Platysolenites antiquissimus.