Biernatia sp.

Hansen, Jesper & Holmer, Lars E., 2011, Taxonomy and biostratigraphy of Ordovician brachiopods from northeastern Ny Friesland, Spitsbergen 3076, Zootaxa 3076 (1), pp. 1-122 : 75-77

Biernatia sp.

Pl. 20, Figs. 14–17; Pl. 21, Fig. 1 , Table 26

Material. 22 ventral valves from samples JH-95, JH-184, F3477, F4997, F5032 and F5316. The figured specimens are TSGF 16942–16944.

Description. Shell with transversely oval commissure and gently convex posterior margin. Larval shell subcircular, 0.15–0.23 mm long, with dense micro-ornamentation consisting of shallow, subequal, circular pits about 3 µm in diameter. Postlarval shell ornamented with growth lines, often becoming slightly rugate. Largest specimen 1.6 mm long and 2.3 mm wide.

Ventral valve high and pointed conical, usually 65–85% as high as long, with slightly concave, high apsacline pseudointerarea and slightly convex anterior slope. Ventral outline distinctly acuminate, subtriangular. Pseudointerarea poorly defined with weak intertrough or lacking any division. Foramen located within larval shell on valve apex. Tube absent. Larval shell conical. L/W ratio 1.12–1.29. Apical process absent or vestigial.

Plate 20

Numericoma ? proclina var. 1

Valhallfonna Formation, Profilbekken Member.

1–2. TSGF16941 , oblique anterolateral view of dorsal valve exterior and detail of larval micro-ornamentation. 26 m above base. Coll. J. Hansen, 04.08.2008, sample JH-184 .

3–4. TSGF16939 , dorsal valve interior, oblique lateral view. 26 m above base. Coll. J. Hansen, 04.08.2008, sample JH-184. 5–6 . TSGF16940 , dorsal valve interior, oblique anterolateral view. 26 m above base. Coll. J. Hansen, 04.08.2008, sample JH- 184 .

7–8. TSGF17040 , dorsal valve interior, oblique anterolateral view. 21 m above base. Coll. J. Hansen, 19.07.2008, sample JH- 23 .

9–10. Ventral valve exterior, oblique lateral view (lost in SEM). 21 m above base. Coll. J. Hansen, 19.07.2008, sample JH-23. Tyronelasma? sp.

Kirtonryggen Formation, base of Nordporten Member. Coll. J. Hansen, 22.07.2008, sample JH-64.

11. TSGF17031, fragment of ventral valve exterior.

12. TSGF17032, fragment of ventral valve exterior.

13. TSGF17030, fragment of ventral valve exterior.

Biernatia sp.

Valhallfonna Formation, Profilbekken Member, 26 m above base. Coll. J. Hansen, 04.08.2008, sample JH-184.

14–15. TSGF16942, ventral valve exterior, oblique lateral view.

16–17. TSGF16944, oblique posterolateral view of ventral valve and larval shell.

Remarks. The Valhallfonna Formation has so far yielded no dorsal valves of this species. The ventral valves show few characters distinguishing the species from others within the genus, prohibiting closer comparison.

Until now, Pre-Darriwilian reports of this genus were restricted to the Baltics and Iran ( Popov et al. 2008). The occurrence in Ny Friesland indicates that the genus was already widespread in the Dapingian.

Occurrence. 92.3 m above base of Olenidsletta Member and about 26, 52, 54 and 67 m above base of Profilbekken Member, Valhallfonna Formation, Basissletta in northeastern Ny Friesland, Spitsbergen.

Figures

FIGURE 1 Locality maps of the Svalbard Archipelago. a) Locations of sites yielding Lower Palaeozoic fossils mentioned in this paper. b) Geological map of the Basissletta plain, northeastern Ny Friesland; redrawn from Fortey & Bruton (1973). The base map is based on aerial photos made available by the Norwegian Polar Institute and on field observations made by the authors in 2008.