Early Acheulian & Developed OldowanB / c)oldupbdIIdiscfig20

Discoid. Upper Bed II, Olduvai Gorge (c. 1.15 - 1.3 MYA). Bifacially trimmed, round in plan. Typical of Early Acheulian 2-dimensional symmetry; the cross-section is not symmetrical. I take this to be a 'one-tiered', 4-faceted set of thematic shapes, in this case two mirror pairs of convex shapes. This is the simplest shape in the Early Acheulian biface series.

Illustration © T. Wynn. T. Wynn. (1989). The Evolution of Spatial Competence. Urbana, IL: University of Illinois Press: fig. 20. (yellow highlight added)