Cyrtospirifer Nalivkin

Baliński, Andrzej, 2002, Frasnian-Famennian brachiopod extinction and recovery in southern Poland, Acta Palaeontologica Polonica 47 (2), pp. 289-305 : 303

Genus Cyrtospirifer Nalivkin in Frederiks, 1929 Cyrtospirifer minor ( Gürich, 1903)

Fig. 8F .

Spirifer Archiaci Vern. var. minor Gürich ; Gürich 1903: 142–143, pl. 1:

4–7. Spirifer Archiaci Vern. var. minor Gür. ; Jarosz 1919: pl. 8: 23. Cyrtospirifer minor ( Gürich, 1903) ; Baliński 1979: 67–69, fig. 22,

pl. 17: 1–11. Material.—Two complete, 11 slightly damaged and 69 fragments of shells and valves.

Remarks.—This small Cyrtospirifer species is one of the commonest brachiopods in the lowermost Famennian beds exposed in trench Z−17 near Dębnik. It is most abundant in set II where it dominates (together with Pampoecilorhynchus geniculatus sp. nov.) the assemblage. Cyrtospirifer minor was described by Baliński (1979) from slightly younger horizons, but still representing Pa. triangularis conodont Zone. The oldest occurrence of the species is in trench Z−6 and the basal set I of trench Z−17 (about 0.7 m below Frasnian– Famennian boundary) in the highest Frasnian Ryocarhynchus tumidus brachiopod zone. C. minor is very rare in this horizon, however, being represented exclusively by single broken valves.

Figures

Fig. 8. Early Famennian brachiopods, trench Z−17, Dębnik anticline, Poland. A, B. Crinisarina angelicoides (Merriam, 1940). A. Complete shell Bp 46/49a in dorsal, lateral, and anterior views. B. Complete shell Bp 46/49b in dorsal, ventral and anterior views. C–E. Pygmis jablonensis (Biernat, 1983); three shells Bp 46/57a, b, and c in dorsal, ventral, lateral, posterior, and anterior views. F. Cyrtospirifer minor (Gürich, 1903); adult shell Bp 46/1a in dorsal, lateral, and anterior views. G. Warrenella sp.; incomplete shell Bp 46/16 in ventral view. All × 1.5.