Anabarites hexasulcatus (Missarzhevsky, 1974)

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 : 421-423

Anabarites hexasulcatus (Missarzhevsky, 1974)

Fig. 76D .

Material.—About 30 internal moulds from samples K2/30 (section 3, Fig. 3), 1/29.2, 1/28.5, 1/6 (section 1, Fig. 4 ), 5a/6, 5a/17.5, and 5a/18.5 (section 96-5a, Fig. 2 ), including figured SMNH X6028, from the Medvezhya, Kugda-Yuryakh, and Emyaksin formations, Anabar Uplift, Siberian Platform, Russia. Correlated with the uppermost Fortunian and lower part of Cambrian Stage 2.

Description.—Conchs usually curved in one plane or irregularly without noticeable torsion, with rounded hexagonal aperture and thin growth lines ( Fig. 76D 1). Lumen (as replicated by internal moulds) subdivided into six rounded longitudinal lobes and intervening grooves. Three of the grooves are usually somewhat deeper than the other three; the shallower grooves split each of the main lobes into a pair of secondary ones. Second-order grooves appear early on the lobes which are delimited by the first-order (i.e., deeper) grooves.

Remarks.—See Kouchinsky et al. (2009) for discussion.

Stratigraphic and geographic range.— Uppermost Fortunian and lower part of Cambrian Stage 2, Siberian Platform, western Mongolia ( Esakova and Zhegallo 1996: 96, pl. 3.17), and probably South China (Kouchinsky et al. 2009).

Figures

Fig. 76. Anabaritids from early Cambrian Medvezhya (A–D) and Emyaksin (F, E) formations, Anabar Uplift, Siberia, Russia; samples K2/25 (A, B), K2/26 (C), section 3; 5/0 (F), section 96-5; 5a/34.5 (E), section 96-5a; and 1/29.2 (D), section 1. A–C, F. Anabarites tristichus Missarzhevsky in Rozanov et al., 1969, SMNH X3671 (A; see also Kouchinsky et al. 2009: fig. 26C), SMNH X3672 (B; see also Kouchinsky et al. 2009: fig. 26D), SMNH X3409 (C; see also Kouchinsky and Bengtson 2002: figs. 2, 3 and Kouchinsky et al. 2009: fig. 26A, B), SMNH X6027 (F). A, B, F, lateral views of calcium phosphatic internal moulds; C1, lateral view of celestite-barite replaced tube with calcium phosphatic internal mould; C2, internal protrusion of the wall enlarged; C3, transverse view. D. Anabarites hexasulcatus (Missarzhevsky, 1974), SMNH X6028; D1, lateral; D2, transverse views. E. Anabarites hariolus (Val’kov, 1987), SMNH X3697 (see also Kouchinsky et al. 2009: fig. 36K–M). E1, transverse view of apertural end; E2, E3, lateral views; E4, transverse view of apical end. Scale bar 25 μm (C2), 500 μm (A, B, C1, C3, D–F).

Fig. 4. The δ13Ccurve for Kotuj River section 1and sampled horizons with fossiliferous samples (arrows with numbers). Shift in stratigraphic column carb at Nemakit-Daldyn–Medvezhya formations contact indicates position of sequence boundary. Stratigraphic ranges and first appearances of fossils (see SOM 1): 2, Oelandiella korobkovi; 3, Securiconus cf. simus; 4, Bemella jacutica?; 8, Anabarella plana; 9, Watsonella crosbyi; 10, Pseudoyangtzespira selindeica; 11, Aldanella crassa; 13, Aldanella attleborensis; 15, Philoxenella spiralis; 16, Barskovia hemisymmetrica; 18, Khairkhania cf. evoluta; 19, Ceratoconus striatus; 21, Salanyella cf. costulata; 23, Purella cristata; 25, Yunnanopleura sp.; 26, Obscurania auriculata; 29, Protoconus cf. crestatus; 32, Siphogonuchites triangularis; 34, Lopochites sp.; 37, first appearance of Halkieria sp.; 39, first appearance of Chancelloria sp.; 40, Tianzhushanella sp.; 42, Khetatheca cotuiensis; 46, Turcutheca sp.; 48, Orthothecid operculum type A; 52, Fomitchella infundibuliformis; 57, Hyolithellus sp.; 62, Selindeochrea missarzhevskyi; 63, Selindeochrea ternaria; 64, Anabarites trisulcatus; 67, Anabarites kelleri; 68, Anabarites biplicatus; 71, Anabarites hexasulcatus; 74, Tiksitheca licis; 75, Cambrotubulus decurvatus; 76, Platysolenites antiquissimus; 77, Blastulospongia sp.

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.