Assemblages of the boat-shaped bivalve Odontogryphaea thirsae (
The larval stage is represented by prodissoconch valves which are about 0.4 mm in height with suborbicular outlines, commarginal striations, and ridge-like, opisthogyral beaks. The juvenile (early dissoconch) stage is expressed by dissoconch valves up to 19 mm in height with elliptical outlines (height > length), indistinct commarginal growth lines, flat commissural planes, and tiny attachment areas on left valves; the valve interiors exhibit a posterior adductor muscle scar, a resilifer, and chomata. The adult (late dissoconch) stage is characterized by dissoconch valves >19 mm in height with subtriangular outlines, prominent commarginal growth lines, wavy commissural planes, and a keel-like terebratuloid fold.
Paleonvironmental and stratigraphic studies of the diversely fossiliferous Odontogryphaea thirsae beds indicate 0. thirsae (