541.0 ± 1.0 – 0 Ma
Name formalityFormal
Usage information
Celestial bodyEarth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Chronological unitEon
Stratigraphic unitEonothem
First proposed byGeorge Halcott Chadwick, 1930
Time span formalityFormal
Lower boundary definitionAppearance of the Ichnofossil Treptichnus pedum
Lower boundary GSSPFortune Head section, Newfoundland, Canada
47°04′34″N 55°49′52″W / 47.0762°N 55.8310°W / 47.0762; -55.8310
GSSP ratified1992
Upper boundary definitionN/A
Upper boundary GSSPN/A
GSSP ratifiedN/A

The Phanerozoic Eon[3] is the current geologic eon in the geologic time scale, and the one during which abundant animal and plant life has existed. It covers 541 million years to the present,[4] and it began with the Cambrian Period when animals first developed hard shells preserved in the fossil record. The time before the Phanerozoic, called the Precambrian, is now divided into the Hadean, Archaean and Proterozoic eons.

The time span of the Phanerozoic starts with the sudden appearance of fossilized evidence of a number of animal phyla; the evolution of those phyla into diverse forms; the emergence and development of complex plants; the evolution of fish; the emergence of insects and tetrapods; and the development of modern fauna. Plant life on land appeared in the early Phanerozoic eon. During this time span, tectonic forces which move the continents had collected them into a single landmass known as Pangaea (the most recent supercontinent), which then separated into the current continental landmasses.

  1. ^ "Phanerozoic". Oxford Dictionaries UK Dictionary. Oxford University Press. Retrieved 2016-01-20.
  2. ^ "Phanerozoic". Merriam-Webster Dictionary.
  3. ^ There are several ways of pronouncing Phanerozoic, including /ˌfæn.ə.rəˈz.ɪk, ˌfæn.rə-, -r-/ fan-ə-rə-ZOH-ik, fan-rə-, -⁠roh-.[1][2]
  4. ^ Cohen, K.M.; Finney, S.C.; Gibbard, P.L.; Fan, J.-X. "International Chronostratographic Chart v 2020/01" (PDF). International Commission on Stratigraphy. Retrieved 22 March 2020.