The PPRG microfossil database (MICRO.DBF) contains information regarding approximately 3500 occurrences of Proterozoic and Early Cambrian microfossils and microfossil-like objects reported from about 470 stratigraphic units, the data included being based on analysis of 316 published papers, monographs, and books. This compilation forms the primary foundation for interpretations discussed in Sections 5.4, 5.5, 11.3, and Chapter 25. Tables 22.1–22.3, below, contain only a fraction of the information stored in the database; a brief description of the types of data stored (and of the database structure) is presented in Chapter 21.

Coverage

Table 22.3 includes an estimated 90 percent of all occurrences of authentic Proterozoic microfossils reported prior to August, 1988. Data from some relatively minor Soviet, Chinese, and Indian papers are not included, and a few significant Chinese monographs appeared too late to be covered. The Early Cambrian data are not comprehensive, but are perhaps representative; about 40% of the reported occurrences of Early Cambrian nonmineralized microfossils have been entered. The coverage in Tables 22.1 and 22.2 is a bit more eclectic. Because of time constraints, a number of papers containing descriptions of nonfossils, pseudofossils, and dubiofossils (see below for definitions) were not analyzed. The amassed data, although not complete, represent the largest compilation of this type now available for Proterozoic microfossils.

Content

Tables 22.1, 22.2, and 22.3 are based on the illustrated literature of Proterozoic and Early Cambrian microfossils and microfossil-like objects.