A. Lebatard

Since its discovery within a travertine quarry, the fragmentary cranium of the only known Turkish Homo erectus, the Kocabas hominid, has led to conflicting biochronological estimations. First estimated to be ∼500 ka old, the partial skull presents a combination of archaic and evolved features that puts it as
an intermediate specimen between the Dmanisi fossils (Homo georgicus) and the Chinese Zhoukoudian skulls (Homo erectus) respectively dated to 1.8 to ∼0.8 Ma. Here we present a multidisciplinary study combining sedimentological, paleontological and paleoanthropological observations together with cosmogenic nuclide concentration and paleomagnetic measurements to provide an absolute chronological
framework for the Upper fossiliferous Travertine unit where the Kocabas hominid and fauna were discovered. The 26Al/10Be burial ages determined on pebbles from conglomeratic levels framing the Upper fossiliferous Travertine unit, which exhibits an inverse polarity, constrains its deposition to before the
Cobb Mountain sub-chron, that is between 1.22 and ∼1.5 Ma. The alternative match of the normal polarity recorded above the travertine with the Jaramillo subchron (lower limit 1.07 Ma) may also be marginally compatible with cosmogenic nuclides interpretation, thus the proposed minimum age of 1.1 Ma for the end of massive travertine deposition. The actual age of the fossils is likely to be in the 1.1–1.3 Ma range. This absolute date is in close agreement with the paleoanthropological conclusions
based on morphometric comparisons implying that Kocabas hominid belongs to the Homo erectus s.l. group that includes Chinese and African fossils, and is different from Middle and Upper Pleistocene specimens. Furthermore, this date is confirmed by the large mammal assemblage, typical of the late
Villafranchian. Because it attests to the antiquity of human occupation of the Anatolian Peninsula and one of the waves of settlements out of Africa, this work challenges the current knowledge of the Homo erectus dispersal over Eurasia.

A discontinuous 200 m-long borehole drilled in the Bol Archipelago (13°N, Lake Chad) provided 25 samples,
which were dated using the 10Be/9Be method and analyzed for their micro-biological content. The dating provided ages ranging from 6.3 ± 0.1 to 2.6 ± 0.1 Ma, a period contemporaneous with the Pliocene fossil localities located in the current Djurab desert of Chad (16–17°N). Well-preserved diatom assemblages first occurred at 4.7 ± 0.1 Ma and were dominated by the freshwater planktonic genera Aulacoseira and Stephanodiscus until the end of the Pliocene. This supports the recurrence of lacustrine
conditions at Bol during all the Pliocene. The presence of pelite and argillaceous deposits in the core before 4.7 ± 0.1 Ma, however, suggests that the lake settled earlier, at least since 6.3 ± 0.1 Ma. The abundance of Afromontane pollen taxa at 4.2 ± 0.1 Ma and the occurrence of trapeziform polylobate phytoliths throughout the sequence suggest significant vegetation inputs from the southern highlands, while the importance of kaolinite in the clay sediments indicates a water supply predominantly from the south during the Pliocene. Phytolith assemblages are all dominated by lobate grass silica short cells and by blocky and elongate types, which attest to the presence of herbaceous dominated vegetation around Bol and/or in the southern drainage basin during the Pliocene. This result is also supported by the pollen assemblage described at 4.2 ± 0.1 Ma, which
shows highest affinity for the savanna biome. Moreover, low values for the Xerophytic grass phytolith index indicate the presence of humid-loving (mesophytic and aquatic) grass communities in this vegetation. At last, significant variations in the abundance of blocky and elongate phytoliths are indicative of local alternations of fully lacustrine and marshy conditions at Bol. Particularly between 3.6 and 2.7 Ma, the abundance of silicified
bulliform cells combined with the absence of diatoms support a significant lacustrine reduction at Bol favoring the increasing of local marshy vegetation.

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 Australopithecus bahrelghazali (Abel) and in the
Toros-Menalla fossiliferous area, TM 266 locality (16°15
N, 17°29
E)
was the site of discovery of Sahelanthropus tchadensis (Toumaı¨).
At both localities, the evolutive degree of the associated fossil
mammal assemblages allowed a biochronological estimation of
the hominid remains: early Pliocene (3–3.5 Ma) at KT 12 and late
Miocene (7 Ma) at TM 266. Atmospheric 10 Be, a cosmogenic
nuclide, was used to quasicontinuously date these sedimentary
units. The authigenic 10 Be/ 9 Be dating of a pelite relic within the
sedimentary level containing Abel yields an age of 3.58
0.27 Ma
that points to the contemporaneity of Australopithecus bahrel-
ghazali (Abel) with Australopithecus afarensis (Lucy). The 28 10 Be/
9 Be ages obtained within the anthracotheriid unit containing
Toumaı¨ bracket, by absolute dating, the age of Sahelanthropus
tchadensis to lie between 6.8 and 7.2 Ma. This chronological
constraint is an important cornerstone both for establishing the
earliest stages of hominid evolution and for new calibrations of the
molecular clock.

The concentrations of atmospheric cosmogenic
10
Be normalized to the solubilized fraction of its stable isotope
9
Be
have been measured in the authigenic phase leached from silicated continental sediments deposited since the upper
Miocene in the northern Chad Basin. This method is validated by the systematic congruence with the
biochronological estimations based on the fossil mammal evolutive degree of faunal assemblages. The fifty-five
authigenic
10
Be/
9
Be ages obtained along 12 logs distributed along two West–East cross sections that encompass best
representative Mio-Pliocene outcrops including paleontological sites show a systematic stratigraphic decrease when
considering all studied sedimentary facies extending from the Pleistocene up to 8 Ma and allow performing geologic
correlations otherwise impossible in the studied area. The resulting global sequence evidences and temporally
specifies the succession of the main paleoenvironments that have developed in this region since the Miocene.
Under the special conditions encountered in the northern Chad Basin, this study demonstrates that the authigenic
10
Be/
9
Be ratio may be used as a dating tool of continental sedimentary deposits from 1 to 8 Ma. The half-life of
10
Be
theoretically allowing dating up to 14 Ma, it may have fundamental implications on important field research such as
paleoclimatology and, through the dating of fossiliferous deposits in paleontology and paleoanthropology.

The sites of Dungo IV and V, southward of Baia Farta, in the Benguela Province (Angola) yielded a new Knowledge of the stratigraphy of the Lower Palaeolithic industries of that part of Angola. The digging of a large wale (Balaenoptera sp.) skeleton at Dungo V showed the presence of numerous lithic artefacts intimately mixed with the animal's bones. Such a discovery gives clear indication of a stranded large marine mammal exploitation for scavenging by a human costal population during an ancient stage of the Palaeolithic period. In a geological context without any volcanic rock, radiodating was not possible. We utilized the method of determination of the burying age of lithic industry by quantity determination of the two cosmogenic nuclides 26Al and 10Be, which gave a burying age of one to two Ma for some artefacts of Dungo IV.

Stratigraphic, sedimentological and paleomagnetic studies were conducted on the travertine from
Denizli Basin, near Kocabas village, in the Denizli region in Turkey, following the paleontological
discovery in 2002. The stratigraphic and sedimentological studies show at least two main cycles of mass
travertine, separated by a fluvial deposit and overlain by a fluvio-lacustrine deposit. These travertines must
have formed in environments with strong hydrodynamics (streams or waterfalls) and are preferentially
located at breaks of slopes. The paleomagnetic study shows that all the quarry travertine presents reverse
magnetic polarity. On the other hand, the detrital fluvio-lacustrine deposit above the travertine presents normal
geomagnetic polarity, except at the top, where it is reversed. Given the presence of an archaic Homo erectus
skull and Villafranchian paleontological remains in the upper travertine unit, the whole travertine dates from
the upper Matuyama, and is more recent than the Olduvai event (1.78 Ma). The normal polarity recorded in the
upper fluvio-lacustrine deposit could correspond to the Cobb Mountain excursion, dated to 1.22 Ma.

The archaic Homo erectus Kocabas¸ skullcap was discovered at Kocabas¸, Denizli, Turkey in travertine
formations over- and underlain by conglomerate formations. These units dated by the 26Al/10Be cosmogenic
nuclide method constrained the skullcap age between 1.0 and 1.6 Ma.

The concentrations of atmospheric cosmogenic 10Be normalized to the solubilized fraction of its stable isotope 9Be have been measured in the authigenic phase leached from silicated continental sediments deposited since the upper Miocene in the northern Chad Basin. This method is validated by the systematic congruence with the biochronological estimations based on the fossil mammal evolutive degree of faunal assemblages.