The study of microfossils. Since the time of A. D. d’Orbigny (1802–57), who is credited with founding the discipline, many thousands of papers have been written on various microfossil groups and many thousands of species have been described. Commercial, or applied, micropalaeontology began in 1877 when the age of strata in a well in Austria was determined by means of Foraminiferida, since when it has become a powerful tool in geologic investigations. Many oil companies either have their own laboratories devoted to micropalaeontology or employ consultants in this field.