Isobythocypris sp .

Fig. 9A

Material examined

ROMANIA • 1 complete carapace; Black Sea, Romanian Continental Shelf, borehole 817LV, sample CM31C; Rhaetian, Upper Triassic; MNHN.F. F63245 • 1 complete carapace; same collection data as for preceding; Rhaetian, Upper Triassic; MNHN.F. F63353 .

Dimensions

RV: L = 470–780 µm; H = 268–427 µm; H/L = 0.55–0.57.

LV: L = 480–798 µm; H = 275–466 µm; H/L = 0.58.

Occurrence

Romanian Continental Shelf, Black Sea, Rhaetian, Upper Triassic (this paper).

Remarks

Isobythocypris Apostolescu, 1959 is mainly distinguished from other bairdiid genera by its lophodont hinge (Apostolescu 1959). More recently, Ainsworth (1990) clarified that Isobythocypris has a subrectangular to elongate subrectangular lateral outline. Only complete carapaces have been retrieved from the CM31 sample so it is impossible to characterize the nature of the hinge in the present material. However, because of its sub-rectangular outline it is attributed to Isobythocypris . Isobythocypris sp. resembles I. dorsoconvexa Ainsworth, 1987 and I. pliensbachensis Ainsworth, 1987 both from the Pliensbachian, Early Jurassic, of the Fastnet Basin, offshore Southwest Ireland (Ainsworth 1987), from which it differs by its shorter oral concavity, less pronounced lateral compression along AVB and its visible, although poorly expressed, dorsal angulations. Isobythocypris sp. is also close to Bairdiacypris triassica postera Herrig, 1979 from the Upper Sinemurian, Early Jurassic, of Thüringen, Germany (Herrig 1979b), but it differs in being more massive and less elongate, with a longer posterior end and a more tapered anterior end.