Almost two decades ago, the Generaldirektion Kulturelles Erbe Rheinland-Pfalz initiated annual field campaigns in order to investigate geological and palaeobiological aspects of the Fossil-Lagerstätte Enspel, an upper Oligocene crater lake. Since then, the fossil-bearing 'oilshale' became more and more exposed due to the removal of the overlying basalt, which is still being commercially exploited. This contribution briefly summarizes the current knowledge that accumulated mainly within the last 20 years, gives a taxonomic listing of the fossil association, and includes a bibliography.