2-Methylretene in sedimentary material: a new higher plant biomarker

2-Methylretene has been synthesised, characterised and identified in sedimentary material from a range of locations, source types and ages. 2-Methylretene was observed only in samples of Permian to Tertiary age and can be associated with specific higher plant precursors that also yield retene. Laboratory dehydrogenation of simonellite yielded 2-methylretene as the major product. Based on this we suggest that 2-methylretene forms from the aromatisation of diterpenoid type natural products with the abietane and phyllocladane skeletons, similar to those that form simonellite and suggest it can be used as a biomarker for higher plant input.