The findings reported here on the probable first occurrence ofthe botryococcene and lycopadiene biosynthetic pathways in the Eocene, coupled with the observation that the production of highly branched isoprenoid alkenes synthesised by diatoms (Volkman et al., 1994) is no more than 92 Ma old (Sinninghe Damsté et al., 2004), provide new insights into the evolution of isoprenoid biosynthetic pathways. There are thought to be around 30,000 biochemicals known today that are based on the isoprenoid skeleton (Lombard and Moreira, 2011), attesting to the diversification of isoprenoid biosynthetic pathways over time. They are found in the three domains of life (Bacteria, Archaea and Eukarya) where they fulfil a remarkably diverse range of biochemical functions