Figure 2. A. Tectonic and paleoceanographic evolution of the Central American Seaway with inferred surface circulation, modified from Duque-Caro (1990) and supplemented with data from Keller and Barron (1983), Vail and Hardenbol (1979), McDougall (1985), Webb (1985), Raffi and Flores (1995), and Kameo and Sato (in press). B. Middle to early late Miocene evolution of the coccolith assemblages in the southern (Colombian Basin) and northern (Yucatan Basin) Caribbean basins and the eastern equatorial Pacific with inferred status of gateway opening and closure on the northern Nicaraguan Rise and along the Central American arc (Kameo and Sato, in press). White rectangles = gateway open; gray rectangles = gateway partially open; black rectangles = gateway closed.