Camarium sp.

Baliński, Andrzej, 2012, The brachiopod succession through the Silurian-Devonian boundary beds at Dnistrove, Podolia, Ukraine, Acta Palaeontologica Polonica 57 (4), pp. 897-924 : 919-920

Camarium sp.

Figs. 18 , 19I .

Material.—Two slightly damaged and three complete juvenile articulated shells. The specimens were recovered at 5.5 m above the S–D boundary (beds 47–48).

Remarks.—The present specimens resemble some meristids in the general shell shape and in the presence of a shoe−lifter, which can be seen as a result of shell exfoliation in the umbonal region of one ventral valve. That is also supported by serial sections ( Fig. 18 ), which confirm the presence of dental plates and a shoe−lifter in the ventral valve, together with a long and high dorsal median septum supporting a narrow, Y−shaped septalium. The absence of mystrochial plates in the sectioned specimen indicates that this form most probably represents Camarium . The specimens are ventribiconvex, subcircular in outline and possess a strongly incurved ventral beak, an extremely weak dorsal fold and ventral sulcus, which result in a weak uniplication of the anterior commissure in large and thick individuals. Kozłowski (1929) identified several meristid specimens from the Mytkiv Beds (former Mitkov Beds) and a few from the Khudykivtsi Beds (former Tajna Beds) as Merista passer (Barrande, 1848) .

http://dx.doi.org/10.4202/app.2011.0138

These differ from the specimens described here by their rather subpentagonal to subrhomboidal instead of circular shell outline, and their more weakly developed ventral sulcus. According to Nikiforova et al. (1985) M. passer is confined to the Mytkiv Beds, whereas rare specimens from the Khudykivtsi Beds appear to represent a new species. Unfortunately, the interiors of the sectioned specimens are incomplete or recrystallised, making impossible the investigations of brachiojugal structures and the material is too scarce to base a formal description of a new taxon.

Figures

Fig. 18. Transverse serial sections through shell of Camarium sp. Numbers refer to distance in mm from ventral umbo. ZPAL Bp. 56/71a. Dnistrove, beds 47–48.

Fig. 19. Athyridide brachiopods from the Silurian–Devonian boundary beds at Dnistrove (Podolia, Ukraine). A–C. Dayia bohemica Bouček, 1941; three shells, ZPAL Bp. 56/200 (A), ZPAL Bp. 56/201 (B), and ZPAL Bp. 56/202 (C), in dorsal (A1, B1, C1), ventral (A2, B2, C2), lateral (A3, B3, C3), posterior (A4, B4, C4), and anterior (A5, B5, C5) views. D–F, J. Dnestrina gutta Nikiforova and Modzalevskaya, 1968. D, E. Two shells, ZPAL Bp. 56/208 (D) and ZPAL Bp. 56/209 (E), in dorsal (D1, E1), ventral (D2, E2), lateral (D3, E3), posterior (D4, E4), and anterior (D5, E5) views. F. Interior view of slightly damaged ventral valve, ZPAL Bp. 56/210. J. Shell ZPAL Bp. 56/207b in dorsal exterior view. G, H. Pseudoprotathyris infantilis (Kozłowski, 1929); two shells, ZPAL Bp. 56/176 (G) and ZPAL Bp. 56/177 (H), in dorsal (G1, H1), ventral (G2, H2), lateral (G3, H3), posterior (G4, H4), and anterior (G5, H5) views. I. Camarium sp.; shell ZPAL Bp. 56/29 in dorsal (I1), ventral (I2), lateral (I3), posterior (I4), and anterior (I5) views. Beds −24 (A–C), −21 (D–F, J), −4 (G, H), and 47–48 (I). Scale bars 2 mm.