[1] GNS Sci, Dept Paleontol, Lower Hutt 5040, New Zealand
[2] Univ Bristol, Sch Chem, Organ Geochem Unit, Cabot Inst, Bristol BS8 1TS, Avon, England
[3] Univ Bristol, Sch Chem, Organ Geochem Unit, Bristol Biogeochem Res Ctr, Bristol BS8 1TS, Avon, England
[4] Purdue Univ, Dept Earth & Atmospher Sci, W Lafayette, IN 47907 USA
[5] Purdue Univ, Purdue Climate Change Res Ctr, W Lafayette, IN 47907 USA
[6] Victoria Univ Wellington, Sch Geog Environm & Earth Sci, Wellington, New Zealand
[7] Univ Southampton, Natl Oceanog Ctr, Sch Ocean & Earth Sci, Southampton SO14 3ZH, Hants, England
[8] Cardiff Univ, Sch Earth & Ocean Sci, Cardiff CF10 3AT, S Glam, Wales
[9] Univ Calif Santa Cruz, Santa Cruz, CA 95060 USA