Ages were determined at two hominid localities from the Chad Basin in the Djurab Desert (Northern Chad).In the Koro Toro fossiliferous area, KT 12 locality (16°00′N, 18°53′E) was the site of discovery of (Toumaï).
The Australopithecus bahrelghazali holotype is precisely located in KT 12 section.
(Toumaï) (1, 2) have changed substantially the understanding of early human evolution in Africa (1–4).
If these requirements are met, then Be reported for surface marine sediments (14, 16), for top surfaces (or extrapolated to zero age) of Fe-Mn deposits (17–23), for present-day deep waters in the Atlantic, Pacific, Indian Ocean, and Mediterranean Sea central basins and margins (13, 24–30) mostly range between 0.5 × 10Be ratio can be expected considering that in continental systems, the two major processes affecting the aqueous geochemistry of beryllium are dissolution from rocks and uptake onto particles (13).
The initial authigenic Be ratio thus depends both on the lithology of the region drained and on the partitioning between solid and aqueous phases.
This is the sole independent dating method available in the study area which, until now is devoid of volcanic deposits appropriate for isotopic and/or radiogenic dating methods.