Dalejina frequens ( Kozłowski, 1929 )

Baliński, Andrzej, 2012, The brachiopod succession through the Silurian-Devonian boundary beds at Dnistrove, Podolia, Ukraine, Acta Palaeontologica Polonica 57 (4), pp. 897-924 : 909

Dalejina frequens ( Kozłowski, 1929)

Fig. 7B .

1929 Rhipidomella frequens sp. n.; Kozłowski 1929: 83–86, pl. 3: 4–22; figs. 21B, 22, 23.

1985 Dalejina frequens ( Kozłowski, 1929) ; Nikiforova et al. 1985:17, pls. 2: 7, 3: 1–4 [full synonymy herein].

Material.—Four shells (2 of them slightly damaged), 4 dorsal and 4 ventral valves. The present material was recovered from the Khudykivtsi Beds at Dnistrove at 5.5 m (beds 47–48) above the S–D boundary.

Remarks.—The studied specimens from Dnistrove, although rather scarce, are externally indistinguishable from specimens illustrated by Kozłowski (1929), Nikiforova (1954), and Nikiforova et al. (1985). The only difference is generally smaller shell size (not exceeding 8 mm in length) attained by the specimens reported here. In this respect they are similar to Dalejina staszici Kozłowski, 1929 , but the latter has a thicker shell with a more pentagonal outline resulting from narrower hinge margin. D. staszici is a rare and stratigraphically older species, occurring only in the Skala Horizon.

According to Nikiforova et al. (1985) D. frequens is abundant in and restricted to the Mytkiv Beds (upper part of the Borshchiv Horizon). The present material, although not numerous, indicates that the species also occurs in the Khudykivtsi Beds.

Stratigraphic and geographic range.— Kozłowski (1929) found the species to range through the Borshchiv Horizon of Podolia. Nikiforova et al. (1985) reported it only from the Mytkiv Beds. Similar form described as D. aff. frequens was reported by Savage (1974: 19–20; pl. 3: 18–32; fig. 8A, B) from the lower Devonian of New South Wales ( Australia).

Figures

Fig. 7. Orthide brachiopods from the Silurian–Devonian boundary beds at Dnistrove (Podolia, Ukraine). A. Resserella elegantuloides (Kozłowski, 1929), complete shell ZPAL Bp. 56/41 in dorsal (A1), ventral (A2), lateral (A3), posterior (A4), and anterior (A5) views. B. Dalejina frequens (Kozłowski, 1929), complete shell ZPAL Bp. 56/35 in dorsal (B1), ventral (B2), lateral (B3), posterior (B4), and anterior (B5) views. C. Talentella crassiformis (Kozłowski, 1929), articulated shell ZPAL Bp. 56/30 in dorsal (C1), ventral (C2), lateral (C3), posterior (C4), and anterior (C5) views. Beds 47–48. Scale bars 5 mm.