Biostratigraphy deals with bodies of rock defined or characterized by their fossil content. Biogeography is concerned with the geographic distribution of organisms. The basic biostratigraphic principles and concepts now in use were developed in the early- to mid-nineteenth century by pioneers such as William Smith (1769–1839), Georges Cuvier (1769–1832), Alcide d'Orbigny (1802–1857), and Albert Oppel (1831–1865) who divided the stratigraphic record into successions of distinct faunal assemblages; the fundamental biostratigraphic unit still in use is the biozone, which usually is named after a dominant or a characteristic species. Fossils were unknown in pre-Cambrian rocks in 1835, when Adam Sedgwick introduced the concept of the Cambrian System; in fact, this interval was subsequently given names that referred to the presumed nonexistent or primitive paleontologic record (Agnotozoic, Archeozoic, Azoic, Eozoic, Protozoic, etc.).

Precambrian paleontology started in the 1850s, with the discovery of remains thought to be organic (for an historical summary, see Section 5.2 and Hofmann 1982, pp. 246–247). Although many of the early reported forms later were shown to be pseudofossils, some were true fossils. The number of accepted fossil occurrences increased slowly over the next 100 years, but only after the Second World War did Proterozoic biotic abundance and diversity become established by discoveries in various parts of the world (see Section 5.2). By the late 1950s, data were sufficient to be put to use in subdividing and correlating sequences locally and regionally, principally in the Soviet Union, giving rise to the subdiscipline of Precambrian biostratigraphy.