Novaplatirostrum sauerlandense Sartenaer, 1997

Halamski, Adam T. & Baliński, Andrzej, 2009, Latest Famennian brachiopods from Kowala, Holy Cross Mountains, Poland, Acta Palaeontologica Polonica 54 (2), pp. 289-306 : 297-299

Novaplatirostrum sauerlandense Sartenaer, 1997

Figs. 6 , 7A–D , 8 .

1997 Novaplatirostrum sauerlandense gen. et sp. nov.; Sartenaer 1997: 31–35, pl. 1: 1–40, fig. 1 [cum syn.].

Material.— 26 specimens from set L, ZPAL Bp 57/38–39, 40–50, 105–112; PIG 163 .II.66.2–6, some of them poorly preserved .

Description.—Shells slightly asymmetrical, ovate, transverse, up to 28.1 mm in width, moderately ventribiconvex. Maximal width at 2/3 of the length, maximal thickness in the posterior region. Anterior commissure uniplicate, deflection broad (0.45–0.65 of the shell width) and very low. Costae apparent only in the anterior third (often less), 2–7 on the fold and 1–3 on lateral slopes.

Ventral interior with dental plates not discernible in the thickened umbonal cavity ( Fig. 6 ); teeth stout, strong; muscle scars deeply impressed on the valve floor. Dorsal interior without median septum; hinge plates divided, posteriorly concave, more anteriorly nearly horizontal; crural bases well marked, with sharp longitudinal, dorsally directed ridge, which continues till the distal ends of crura ( Fig. 6 ).

Remarks.—The described material from Kowala is similar both externally and internally to the type collection from the Wocklumian of Sauerland ( Germany) figured by Sartenaer (1997: pl. 1). The difference between values of the length to width ratio (0.73 to 0.98, mean 0.86 at Kowala; 0.72 to 0.88, mean 0.82 in Sauerland) is not significant. The pattern of variation of number of ventral costae is also broadly similar in both samples, even if Kowala material is clearly more variable than that from Sauerland (a smaller sample is more varied, Fig. 8 ): the extreme representatives, with 3 and 7 ventral costae respectively are shown in Fig. 7A and D .

Poorly preserved middle to late Famennian Planovatirostrum planoovale sensu Biernat and Racki (1986a) (= Planovatirostrum sp. 1 here) and Planovatirostrum cf. undulatum sensu Biernat and Racki (1986a) (= Planovatirostrum sp. 2 here; both from Kowala) differ in being more transverse (length to width ratio 0.72 to 0.82 in the former, 0.70 in the later). Even if their specific identification can hardly be attempted, they may be attributed to the genus Planovatirostrum Sartenaer, 1970 ( Sartenaer and Xu 1989). The stratigraphic separation between two members of the same evolutionary lineage, namely Planovatirostrum in the middle and late Famennian ( UD−III to UD−V) and Novaplatirostrum in the latest Famennian ( UD−VI) observed by Sartenaer (1997) in Sauerland and in Thuringia is therefore valid also at Kowala, even if the age of the latter taxon cannot be given in such detail as in Germany.

Stratigraphic and geographic distribution.—Holy Cross Mountains, Sauerland; Famennian, most probably UD−VI ( Sartenaer 1997).

Figures

Fig. 6. Transverse serial sections of Novaplatirostrum sauerlandense Sartenaer, 1997 through shell ZPAL Bp 57/40 from Kowala, set L. Numbers indicate distances in mm from ventral umbo.

Fig. 7. Middle to Latest Famennian brachiopods from Kowala. A–D. Novaplatirostrum sauerlandense Sartenaer, 1997; four shells ZPAL Bp 57/106, 39, 38, and 105, respectively, in dorsal (A1, B1, C1, D1), ventral (A2, B2, C2, D2), lateral (A3, B3, C3, D3), posterior (A4, B4, C4, D4), and anterior (A5, B5, C5, D5) views. E. Hadyrhyncha sp.; shell ZPAL Bp 57/115 in dorsal (E1), ventral (E2), lateral (E3), posterior (E4), and anterior (E5) views. F, G. Centrorhynchus sp.; external imprints ZPAL Bp 57/61 and 62, respectively, of two strongly flattened ventral valves on a shale surface.

Fig. 8. Biometrical characteristics of Novaplatirostrum sauerlandense Sartenaer, 1997 from the type section (after Sartenaer 1997) and from Kowala. A. Comparison of the shell outline of representatives of the two collections on a width to length scatter diagram. B. Comparison of costation of the two collections.