Early Acheulian & Developed OldowanB / g)peninj17
Biface/Handaxe. Peninj, West Natron, Tanzania (c. 1.3-1.5 MYA). A variant of the previous biface shapes, this biface appears to consist also of a mirror pair of curvilinear shapes on either side, but with a rectilinear+natural shape at the top and curvilinear+natural shape at the bottom.
Illustration © T. Wynn. T. Wynn. (1989). The Evolution of Spatial Competence. Urbana, IL: University of Illinois Press: fig. 17. (yellow highlight added)