Phanerozoic
Geologic time scale
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The Phanerozoic is the current and the latest of the four geologic eons in the Earth's geologic time scale, covering the time period from 538.8 million years ago to the present. Wikipedia
Age: about 541 million years
Occurred: 541 (+/- 1) million years ago - 0 million years ago
Chronological unit: Eon
First proposed by: George Halcott Chadwick, 1930
Lower boundary definition: Appearance of the Ichnofossil Treptichnus pedum
Lower boundary GSSP: Fortune Head section, Newfoundland, Canada; 47°04′34″N 55°49′52″W / 47.0762°N 55.8310°W