TERTIARY TO PRESENT/Eocene 467 Figure Time chart of the Eocene, showing how it is divided up by ages/stages, magnetochrons (chron C), and global calcareous nannoplankton (NP) and planktonic foraminiferal (P) biozones Also shown are an isotope proxy temperature curve and the main biotic events in the sea and on land Magnetochrons are divided into normal (black) and reversed (white) intervals; the normals (n), often composite, are younger than the reversals (r) that bear the same number CIE, Carbon Isotope Excursion; EECO, Early Eocene Climatic Optimum; MDE, Mammalian Dispersal Event; PETM, Paleocene Eocene Thermal Maximum Data for the isotope curve from Zachos J, Pagani M, Sloan L, Thomas E, and Billups K (2001) Trends, rhythms, and aberrations in global climate 65 Ma to present Science 292: 686 693 Absolute dates from Gradstein F, Ogg J, and Smith A (in press) A Geological Timescale 2004 Cambridge University Press, Cambridge