Pleistocene

Japanese: Pleistocene

…One of the geological time periods. It is synonymous with the Pleistocene (also called the latest epoch). The Cenozoic Era is called the mammalian age and is divided into the Tertiary and Quaternary periods, but the boundary between the two periods is when humans and modern mammals appeared, the warm climate became cold, and glaciers began to develop, so the Quaternary period is also called the Anthropogenic Age or the Ice Age. …

From the Quaternary Period

…In 1833, C. Lyell named the top layer of the Tertiary System as the Pleistocene, and the layer containing human remains as the Modern Era, based on the percentage of extant species in fossil shells. Later, Lyell renamed the Pleistocene to the Pleistocene, and defined it as the epoch containing more than 70% extant species based on the percentage of extant shell fossils. …

*Some of the terminology that mentions "Pleistocene" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…地質時代区分の一つ。更新世(最新世ともいう)Pleistoceneと同義である。新生代は，哺乳類時代とよばれ，第三紀と第四紀に区分されるが，両紀の境界は，人類および現在型の哺乳類が現れ，温暖な気候が寒冷化して氷河が発達し始めた時期においており，第四紀は，人類時代とも氷河時代ともよばれる。…