Ryssochonetes Johnson, 1970

Baliński, Andrzej, 2002, Frasnian-Famennian brachiopod extinction and recovery in southern Poland, Acta Palaeontologica Polonica 47 (2), pp. 289-305 : 294

Genus Ryssochonetes Johnson, 1970 ? Ryssochonetes sp.

Fig. 3J .

Material.—One partially exfoliated specimen embedded in matrix from the lowest beds (set I) of trench Z−17 and six additional fragmentary specimens etched using acetic acid from the limestone (upper part of the set II); one specimen from topmost layer of trench Z−17.

Remarks.—The species is characterized by its small shell with radial costellae crossed by concentric undulating fila. The internal shell structure of the species remains unknown because of the poor preservation of available specimens.

Occurrence.—This species was found in the highest Frasnian (set I) and in the lowest Famennian (the upper part of the set II, the Early Pa. triangularis Zone ) of the section in trench Z−17. One fragmentary shell was recovered in the uppermost bed of the trench (set III, the Middle Pa. triangularis Zone ).

Figures

Fig. 3. Early Famennian brachiopods, trench Z−17, Dębnik anticline, Poland. A. Barroisella campbelli Cooper, 1942; partially exfoliated shell Bp 46/48a in dorsal view; × 3. B–D. Praewaaagenoconcha cf. speciosa (Hall, 1867). B. Exterior of the ventral valve Bp 46/20a. C, D. Internal view of two partially exfoliated dorsal valves Bp 46/25a and Bp 46/25b; × 1.5. E–G. Nigerinoplica sp. E, F. Side view of two shells Bp 46/24a and Bp 46/18a. G. Shell Bp 46/24b in dorsal view showing partially removed ventral valve and interior of the dorsal valve; × 1.5. H. Schizophoria (Schizophoria) sp.; incomplete shell Bp 46/37a in dorsal view; × 1.5. I. Rhipidomellid gen. et sp. indet; exterior of poorly preserved ventral valve Bp 46/40; × 2. J.?Ryssochonetes sp.; incomplete shell Bp 46/15 in ventral view; × 15. K. Longispina sp.; poorly preserved shell Bp 46/17z in ventral view; × 5.