[1] CSIC, Dept Environm Chem, Inst Chem & Environm Res, ES-08034 Barcelona, Catalonia, Spain
[2] Univ Barcelona, GRC Marine Biosci, Dept Stratig & Paleontol, Barcelona 08071, Spain
[3] Univ Salamanca, Dept Geol, Fac Sci, E-37008 Salamanca, Spain
[4] Univ Cambridge, Godwin Lab, Cambridge CB2 3SA, England