When did the Phanerozoic Eon begin?
Geological history of Earth
The Phanerozoic Eon is the current eon in the geologic timescale. It covers roughly 541 million years. During this period continents drifted about, eventually collected into a single landmass known as Pangea and then split up into the current continental landmasses.
Paleoarchean
The Paleoarchean (), also spelled Palaeoarchaean (formerly known as early Archean), is a geologic era within the Archaean Eon. It spans the period of time —the era is defined chronometrically and is not referenced to a specific level of a rock section on Earth. The name derives from Greek "Palaios" "ancient". The oldest ascertained life form of fossilized bacteria in microbial mats, old, found in Western Australia, is from this era. The first supercontinent Vaalbara formed during this period.