 The smaller skulls are evidence that sexual dimorphism was the reason for the size difference.Consistent evidence of Lower Pleistocene hominids supports that there was a variation in size of the "Australopithecus" in East Rudolf, and not a separate species.With the occipital only being present the morphology could not be confirmed, but the KNM-ER 406 and the other fossil found a mile North of the site are consistent with fossils found in Olduvai.