Retrieval of viable bacteria from fossil material dating from the Oligocene back to the Miocene opens the opportunity to study the evolution of prokaryotes through the evolution of their DNA, their physiology, and their ecology. This unique system in which ancient organisms and their genes may be compared directly, rather than by inference, with modern homologues is without precedent. Clearly, however, confirmation of the fossil origin of such isolates must be made in a manner that would allay reasonable skepticism. Present approaches of verification of authenticity of fossil DNA are either arbitrary or potentially unconvincing, because of their dependence on imprecise methodological observations. New approaches for verification must be developed at the same time as further research in fossil bacterial isolation and characterization proceeds. The discovery that viable bacterial spores from fossil materials opens the way to direct assessment of the evolution of complex biochemical systems in prokaryotic systems and to explore mechanisms for long term survival of microorganisms.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.