Russell Earl Marker (March 12, 1902 – March 3, 1995) was an American chemist who invented the octane rating system when he was working at the Ethyl Corporation.[1][2] Later in his career, he went on to found a steroid industry in Mexico when he successfully made semisynthetic progesterone from chemical constituents found in Mexican yams in a process known as Marker degradation.[1][3] This eventually led to the development at Syntex of the combined oral contraceptive pill and synthetic cortisone – and to the development of the Mexican barbasco trade.