Platysolenites antiquissimus Eichwald, 1860

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 : 425-427

Platysolenites antiquissimus Eichwald, 1860

Figs. 81 , 82H, SOM 3.

Material.— More than 140 specimens, including figured SMNH X6056–6064 , 6072 , from samples 1/A, 1/54, 1/46, 1/45, 1/29.5, 1/29.2, 1/27.5, 1/25.5, 1/22.5, 1/22 (section 1, Fig. 4 ), K1b/9, 2/A, K1a/24, K1a/25, K1a/26, K1a/27, K1a/28, K1a/42A, K1a/45, K1a/47, K1a/48, K1a/82 (section 2, Fig. 1), 3/0, 3/6.5, 3/10, 3/12, 3/12.5, 3/20.5, K2/12, K2/20, K2/21, K2/22, K2/24, K2/30, K2/33, K2/43, K2/50 (section 3, Fig. 3), 5/0.5, 5a/1, 5a/5, 5a/6, 5a/8, 5a/9, 5a/18.5, and 5a/34.5 (sections 96-5 and 96-5a, Fig. 2 ), Nemakit-Daldyn, Medvezhya, and Emayksin formations. Correlated with the Fortunian and lower part of Cambrian Stage 2 .

Description.—Tubes composed of siliceous or clay grains (up to 5 mm long and up to 0.7 mm in diameter) with circular cross-section and straight aperture. The tubes have straight tranverse annulation ( Fig. 81I ) and granular composition of the wall, which is up to 70 μm thick.

Remarks.— Platysolenites is interpreted as a sedentary foraminiferan with agglutinated tests that commonly contain grains of quartz and K-feldspar (e.g., Glaessner 1978; Felitzyn 1992; McIlroy et al. 1994). The tests show an elastic deformation that suggests that they were not rigid in life

Fig. 81C–F ). A bulbous initial part (proloculus of McIlroy et al. 2001) is invariably missing from our material. Some of the fragments presumably preserve a circular aperture

Fig. 81A, D, G ). Finds of agglutinated spherical tests of Blastulospongia sp. (see below) similar in composition to tubular Platysolenites antiquissimus are consistent with a protistan affinity of both of these fossils.

Tubular fossils defined as Platysolenites sp. are illustrated from drill cores from the subsurface margins of the Siberian Platform (east Western Siberia; Kontorovich et al. 2008), where they co-occur with the upper Ediacaran Cloudina –Namacalathus assemblage (Zhuravlev et al.

2012). Platysolenites is also reported from Purella Zone equivalent beds on the northwestern and southern flanks of the Anabar Uplift by Missarzhevsky (1989: 212). The species is known from drill cores in the northern inner part of the Siberian Platform (Khomentovsky et al. 1998), although never previously illustrated or adequately described from the Cambrian deposits of the Siberian Platform. This report shows that P. antiquissimus commonly occurs in the Nemakit-Daldyn, Medvezhya and lower Emyaksin formations of the Anabar Uplift. Thus, most occurrences of the species from Siberia are from the Fortunian Stage. In contrast with terrigenous deposits of Laurentia, Baltica and Avalonia, the species in Siberia occurs mainly in carbonate deposits.

Stratigraphic and geographic range.— Uppermost Ediacaran? of Siberia (Kontorovich et al. 2008; Zhuravlev et al. 2012); Terreneuvian Series of Siberia, Baltica, Laurentia, and Avalonia ; Cambrian Stage 3 of Baltica, Laurentia, Avalonia, and Armorica (McIlroy et al. 2001; Streng et al. 2005, and references therein).

Figures

Fig. 81. Foraminifer? Platysolenites antiquissimus Eichwald, 1860, siliceous tubes from early Cambrian Nemakit-Daldyn (A, B, E), Medvezhya (D, F–I), and Emyaksin (C) formations, Anabar Uplift, Siberia, Russia; samples K1a/26A (A, B), K1a/28A (F), section 2; 5a/1 (C), section 96- 5a; 1/A (E), 1/22 (H, I), section 1; K2/21 (D, G), section 3. A–I. SMNH X6056–6064, respectively. Scale bar 500 μm (D, H, I), 1 mm (A–C, E–G).

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.