How did the International Commission on Stratigraphy change the status of the Quaternary Period in 2008?

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Quaternary paleogeography — Quaternary Distribution of landmasses, mountainous regions, shallow seas, and deep ocean basins during the Quaternary Period. Included in the paleogeographic reconstruction are the locations of the interval's subduction zones.

In 2008, the International Commission on Stratigraphy (ICS) abandoned its previous proposal to classify the Quaternary as an informal sub-era of the Cenozoic Era. Instead, the commission formally designated the Quaternary as the uppermost period of the Cenozoic Era, positioning it to follow the Paleogene and Neogene periods.1

This decision was subsequently ratified in 2009 by the International Union of Geological Sciences, which officially set the beginning of the Quaternary Period at 2,588,000 years ago.12