The Chelleo-Acheulean is a Palaeolithic stone tool industry that is marks a transitional stage between the Chellean (Abbevillian or Oldowan) and the Acheulean. Louis Leakey identified eleven stages of development in the Chelleo-Acheulean "hand axe culture" in Africa.
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Chelleo-Acheulean Wikipedia(Text) CC BY-SA