Early Acheulian & Developed OldowanB / k)peninj28
Biface/Handaxe. Peninj, West Natron, Tanzania (c. 1.3-1.5 MYA). This Early Acheulian biface ('handaxe') takes us to the next level of complexity. It appears to have a 'two-tiered', 6-faceted set of thematic shapes. If I read it right, there is a mirror pair of curvilinear shapes on either side of the lower tier and a concave shape on the upper tier opposite what is eitehr a convex shape or a failed attempt at concavity. At the top it has a rounded natural shape in symmetrical opposition to a pointed trimmed shape at the bottom.
Illustration © T. Wynn. T. Wynn. (1989). The Evolution of Spatial Competence. Urbana, IL: University of Illinois Press: fig. 28. (yellow highlight added)