[…] Seifert was the one who coined the term “biomarker” from their original “biological marker,” perhaps because it sounded catchier, especially in an industry [oil industry] that was more interested in rocks than biology. The term caught on, even as the work with petroluem biomarkers moved farther and farther from the original concept of a biological marker—from understanding the history of life or the biological origin of hydrocarbons in petroleum, to chronicling the history of rocks and the fate of the hydrocarbons themselves.In the glossary of the book Echoes of Life , the term Biomarker is defined as follows:
An organic compound in natural waters, sediments, soils, fossils, crude oils, or coal that can be unambiguously linked to specific precursor molecules made by living organisms.Biological marker, molecular fossil, fossil molecule, and geochemical fossil are given as synonymous expressions for the word biomarker.
From a kinetics viewpoint, biomarkers are organic reaction products (or the molecules thereof)—often decomposition products of much larger biomolecules or supramolecular structures.
Keywords: organic geochemistry, biochemistry, paleontology, history
 Susan M. Gaines, Geoffrey Eglington, and Jürgen Rullkötter: Echoes of Life • What Fossil Molecules Reveal about Earth History. Oxford University Press, New York, 2009; pp. 83-84 and glossary.