Thursday, July 27, 2006
A conundrum about the chemical make-up of fossilized insects has been solved this week by scientists who baked up scorpions to find the answer.
Modern arthropods, including cockroaches, scorpions, beetles and shrimps, have shells made up of chitin. Chitin consists of stringy carbohydrate fibres rather like plant cellulose that are embedded in a hard protein matrix, with a waxy layer on top. But their fossilized counterparts, explains Neal Gupta of Yale University in New Haven, Connecticut, have an entirely different chemical make-up. Fossils surviving from 30 million years ago have an outside skeleton containing 'aliphatic' molecules with long chains of carbon atoms, very similar in structure to the chemical compound kerogen, a precursor to components of petrol.
'This is an enigma,' says co-author Richard Pancost of Bristol University, UK. 'How do you go from chitin, the carbohydrate, to these long-chain hydrocarbon precursors?'