Gyrostrea sp. B

Musavu Moussavou, Benjamin, 2017, Systematics, palaeoecology and taphonomy of Turonian oysters from the northern Gabon Coastal Basin, Geodiversitas 39 (2), pp. 213-224 : 220

Gyrostrea sp. B

( Fig. 4 F)

MATERIAL. — 1 specimen (MDG/LBV/Lm-14).

OCCURRENCE. — Turonian of Gabon (this study).

DESCRIPTION

Shell, represented only by LV, is large, inequilateral, elongated to oval in outline. Valve is strongly convex, inflated. Beak is opisthogyrally spiral. Anterior margin is spirally curved. Its posterior margin is straight, curving into ventral margin which evenly rounded. Attachment area is small. Ornamentation consisting of radial ribs near the umbonal area with concentric growth lamellae which becoming concentric ribs toward central part and margin ventral.

REMARK

Gyrostrea sp. B differs from Gyrostrea sp. A in having concentric ribs.

Figures

FIG. 4. — A-D, Ostrea sp. D: A, B, MDG/LBV/Lm-33.1; C, D, MDG/LBV/Lm-33.2; E, Ostrea sp. C MDG/LBV/Lm-32.1; F, Gyrostrea sp. B MDG/LBV/Lm-14; G-N, Gyrostrea delettrei (Coquand,1862);G, H, MDG/LBV/Lm-12.1;I, J, MDG/LBV/Lm-12.2;K, L, MDG/LBV/Lm-12.3,M-N.MDG/LBV/Lm-12.4;O-R, Ostrea sp.B;O, P, MDG/LBV/Lm-31.1;Q, R, MDG/LBV/Lm-31.2;S-U, Ostrea sp.A,S-T.MDG/LBV/Lm-15.1;U, MDG/LBV/Lm-15.2.Scale bar:1 cm.