Paleontologists often refer to faunal stage（英语：faunal stage）s rather than geologic (geological) periods. The stage nomenclature is quite complex. For an excellent time-ordered list of faunal stages, see The Paleobiology Database. [2006-03-19]. （原始内容存档于2006-02-11）.
Pamela J.W. Gore. The Precambrian. [12/6/06]. （原始内容存档于2007-01-02）.请检查|access-date=中的日期值 (帮助)
Paleontologists often refer to faunal stage（英语：faunal stage）s rather than geologic (geological) periods. The stage nomenclature is quite complex. For an excellent time-ordered list of faunal stages, see The Paleobiology Database. [2006-03-19]. （原始内容存档于2006-02-11）.
Paleontologists often refer to faunal stage（英语：faunal stage）s rather than geologic (geological) periods. The stage nomenclature is quite complex. For an excellent time-ordered list of faunal stages, see The Paleobiology Database. [2006-03-19]. （原始内容存档于2006-02-11）.
Dates are slightly uncertain with differences of a few percent between various sources being common. This is largely due to uncertainties in 放射性定年法 and the problem that deposits suitable for radiometric dating seldom occur exactly at the places in the geologic column where they would be most useful. The dates and errors quoted above are according to the 國際地層委員會 2004 time scale. Dates labeled with a * indicate boundaries where a 全球界线层型剖面和点位 has been internationally agreed upon: see List of Global Boundary Stratotype Sections and Points（英语：List of Global Boundary Stratotype Sections and Points） for a complete list.
Though commonly used, the Hadean is not a formal eon and no lower bound for the Archean and Eoarchean have been agreed upon. The Hadean has also sometimes been called the Priscoan or the Azoic. Sometimes, the Hadean can be found to be subdivided according to the lunar geologic time scale. These eras include the Cryptic and Basin Groups (which are subdivisions of the Pre-Nectarian era), Nectarian, and Early Imbrian（英语：Early Imbrian） units.
