Systematics, palaeoecology and taphonomy of Turonian oysters from the northern Gabon Coastal Basin Author Musavu Moussavou, Benjamin text Geodiversitas 2017 2017-06-30 39 2 213 224 journal article 31257 10.5252/g2017n2a3 f9e855d7-6356-4312-8dbe-c3dd884d6277 1069848 F4D33955-5823-49E9-BC9A-26DFB03038A7 Ostrea sp. A ( Fig. 4 S-U) MATERIAL . — 10 specimens (MDG/LBV/Lm-15.1 to Lm-15.10). OCCURRENCE . — Turonian of Gabon (this study). DESCRIPTION Shell is large, inequivalve, inequilateral, elongated, subtrigonal to suborbicular in outline. Umbo is small and prominent. Anterior and ventral margin are rounded. Posterior margin straight is angulated toward ventral margin. Attachment area is small. LV is slightly inflated. RV is flat. Ornamentation of LV consisting of numerous radial subacute ribs. This ribs start at the umbonal area, occasionally carrying small spines near ventral margin, and crossed by growth lamellae at irregular intervals. RV is ornamented by concentric fine growth squamae. REMARK Ostrea sp. A differs from Ostrea lateralis Nilsson, 1827 in having an angulated posterior margin without fold.