Figure F2. Neogene Southern Ocean radiolarian zonation and secondary events (from compilation by A. Weinheimer, in Shipboard Scientific Party, 1999). T = top, B = bottom, TC = top common, BC = bottom common, ET = evolutionary transition. Events defining full zone boundaries are shown in bold. Numbers in parentheses are the sources of the ages: 1 = Lazarus (1990), 2 = Caulet (1991), 3 = Hays and Opdyke (1967), 4 = Lazarus (1992), 5 = Abelmann (1992).