The record of trace fossils across the Proterozoic–Cambrian boundary

Numerous studies have shown that there is a dramatic increase in the abundance and diversity of trace fossils at about the base of the Cambrian (Seilacher, 1956; Daily, 1972; Crimes, 1975, 1987; Alpert, 1977; Fedonkin, 1980a,b; Brasier, 1982; Urbanek and Rozanov, 1983; Crimes and Anderson, 1985; Fritz and Crimes, 1985; Nowlan et al., 1985; Paczesna, 1986; Narbonne et al., 1987). Accordingly, the possibility of using trace fossils to define or correlate the base of the Cambrian System has been widely discussed (Daily 1972; Alpert, 1977; Fedonkin, 1980a; Crimes and Anderson, 1985; Crimes, 1987; Narbonne et al., 1987).