3D virtual rendering of the natural endocast of KNM-ER 3732 and identification of sulcal imprints. KNM-ER 3732 is shown in lateral right (A), lateral left (B) and dorsal (C) views. Images not to scale. ar: ascending ramus of the lateral fissure; c: central sulcus; CO: coronal suture; fi: inferior frontal sulcus; fm: middle frontal sulcus; ip: intra-parietal sulcus; pc: pre-central sulcus; pt: post-central sulcus.

Comparison of the sulcal patterns identified in the inferior frontal area of KNM-ER 3732. The natural endocast (A) and braincase (B) of KNM-ER 3732 are compared to the virtual endocasts of extant human (C) and chimpanzee (D) individuals. Images not to scale. ar: ascending ramus of the lateral fissure; c: central sulcus; co: coronal suture; fi: inferior frontal sulcus; fm: middle frontal sulcus; ip: intra-parietal sulcus; pc: pre-central sulcus; pt: post-central sulcus.