Tellina sp.

Hryniewicz, Krzysztof, Amano, Kazutaka, Bitner, Maria Aleksandra, Hagström, Jonas, Kiel, Steffen, Klompmaker, Adiël A., Mörs, Thomas, Robins, Cristina M. & Kaim, Andrzej, 2019, A late Paleocene fauna from shallow-water chemosynthesis-based ecosystems, Spitsbergen, Svalbard, Acta Palaeontologica Polonica 64 (1), pp. 101-141 : 120

? Tellina sp.

Fig. 15 .

1925 Lamellibranchiate 2; Hägg 1925: 48, pl. 5: 22–22a.

Material. — One specimen ( NRM-PZ Mo 149165), internal mold with fragments of the shell preserved, from the upper Paleocene of Fossildalen , Spitsbergen, Svalbard .

Measurements. —NRM-PZ Mo 149165: L, 10.4 mm; H, 5.2 mm; W, 3.5 mm.

Description. —Shell small, elongate, with umbones positioned roughly medially. Anterodorsal and posterodorsal margins straight, with anterior margin slightly truncated, ventral margin broadly rounded, posterior margin weakly pointed. External ornament composed of commarginal growth lines; weak sulcus visible in posterodorsal shell area. Ligament external, short, positioned posterior to umbo. Internal features unknown.

Remarks. —The current species was previously listed as an unnamed bivalve by Hägg (1925). We classify it as a tellinid based on its shell shape and the presence of an external ligament; the elongation and roughly equidistant position of the umbo suggests ascription to Tellina rather than to Macoma Leach, 1819 .

Several tellinids have been reported from Paleocene deposits of Greenland ( Petersen and Vedelsby 2000). Among those, Tellina sp. 1 is less elongate, whereas Tellina sp. 2 has the umbo positioned closer to the anterior of the shell than the species reported here. Macoma sp. 1 and Macoma sp. 2 . are both less elongate than the species reported here. Tellinimera scitula ( Meek and Hayden, 1856) from the uppermost Maastrichtian (Upper Cretaceous) Fox Hills Formation in South Dakota, USA, has a less pointed umbo, is less elongate and has more rounded anterodorsal and posterodorsal margins than the Paleocene? Tellina sp. described here. Tellinimera kauffmani Marincovich, 1993 , from the Danian (lower Paleocene) Prince Creek Formation in northern Alaska, USA, is similar in shape to the species reported here, but has a less pointed umbo and weakly convex anterodorsal and posterodorsal margins as opposed to straight in? Tellina sp.

Figures

Fig. 15. Tellinid bivalve?Tellina sp. from the upper Paleocene, Basilika Formation, Fossildalen, Spitsbergen, Svalbard. NRM-PZ Mo 149165, partial shell, left valve view (A1), dorsal view showing partially preserved opisthodethic external ligament (A2).