A. Lebatard | Aix-Marseille University (original) (raw)
Papers by A. Lebatard
Since its discovery within a travertine quarry, the fragmentary cranium of the only known Turkish... more 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 ... more 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.
Chemical Geology, 2008
The high proportion of crystallized apatite forming the bones and teeth should theoretically allo... more The high proportion of crystallized apatite forming the bones and teeth should theoretically allow the use of fission track analysis to date vertebrate fossils when burying of the fossiliferous series did not subject them to temperatures exceeding 60°C. However several major obstacles arise such as the complexity of fossils' internal structures, diagenetic modifications and substitutions of the hydroxyapatite by other minerals, and massive U uptake or loss during diagenesis. In this work, those various problems are addressed combining optical microscope observation of the fossils, a systematic fission track analysis of the best samples, α and γ spectrometry and Secondary Ion Mass Spectrometry. Even if the problems caused by internal structures and mineral substitutions can be solved, U movements in and out of the fossils are generally too complex to allow fission track analysis dating of the fossils.
Ages were determined at two hominid localities from the Chad Basin in the Djurab Desert (Northern... more 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°00N, 18°53E) was the site of
discovery of Australopithecus bahrelghazali (Abel) and in the
Toros-Menalla fossiliferous area, TM 266 locality (16°15N, 17°29E)
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 ... more 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... more 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 D... more 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 travert... more 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.
by D. Bourlès, Régis Braucher, Marina Mosquera, Antonio Rosas, Andreu Ollé, A. Lebatard, Josep Maria Vergès, Maria Bennàsar, Isabel Cáceres, Ángel Carrancho, and Isabel Expósito Barea
PLoS ONE, 2014
The first arrivals of hominin populations into Eurasia during the Early Pleistocene are currently... more The first arrivals of hominin populations into Eurasia during the Early Pleistocene are currently considered to have occurred as short and poorly dated biological dispersions. Questions as to the tempo and mode of these early prehistoric settlements have given rise to debates concerning the taxonomic significance of the lithic assemblages, as trace fossils, and the geographical distribution of the technological traditions found in the Lower Palaeolithic record. Here, we report on the Barranc de la Boella site which has yielded a lithic assemblage dating to ,1 million years ago that includes large cutting tools (LCT). We argue that distinct technological traditions coexisted in the Iberian archaeological repertoires of the late Early Pleistocene age in a similar way to the earliest sub-Saharan African artefact assemblages. These differences between stone tool assemblages may be attributed to the different chronologies of hominin dispersal events. The archaeological record of Barranc de la Boella completes the geographical distribution of LCT assemblages across southern Eurasia during the EMPT (Early-Middle Pleistocene Transition, circa 942 to 641 kyr). Up to now, chronology of the earliest European LCT assemblages is based on the abundant Palaeolithic record found in terrace river sequences which have been dated to the end of the EMPT and later. However, the findings at Barranc de la Boella suggest that early LCT lithic assemblages appeared in the SW of Europe during earlier hominin dispersal episodes before the definitive colonization of temperate Eurasia took place.
Earth and Planetary Science Letters, 2010
The concentrations of atmospheric cosmogenic 10Be normalized to the solubilized fraction of its s... more 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.
PLoS ONE, 2014
The first arrivals of hominin populations into Eurasia during the Early Pleistocene are currently... more The first arrivals of hominin populations into Eurasia during the Early Pleistocene are currently considered to have occurred as short and poorly dated biological dispersions. Questions as to the tempo and mode of these early prehistoric settlements have given rise to debates concerning the taxonomic significance of the lithic assemblages, as trace fossils, and the geographical distribution of the technological traditions found in the Lower Palaeolithic record. Here, we report on the Barranc de la Boella site which has yielded a lithic assemblage dating to ,1 million years ago that includes large cutting tools (LCT). We argue that distinct technological traditions coexisted in the Iberian archaeological repertoires of the late Early Pleistocene age in a similar way to the earliest sub-Saharan African artefact assemblages. These differences between stone tool assemblages may be attributed to the different chronologies of hominin dispersal events. The archaeological record of Barranc de la Boella completes the geographical distribution of LCT assemblages across southern Eurasia during the EMPT (Early-Middle Pleistocene Transition, circa 942 to 641 kyr). Up to now, chronology of the earliest European LCT assemblages is based on the abundant Palaeolithic record found in terrace river sequences which have been dated to the end of the EMPT and later. However, the findings at Barranc de la Boella suggest that early LCT lithic assemblages appeared in the SW of Europe during earlier hominin dispersal episodes before the definitive colonization of temperate Eurasia took place.
Proceedings of the National Academy of Sciences, 2008
Ages were determined at two hominid localities from the Chad Basin in the Djurab Desert (Northern... more 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°00N, 18°53E) was the site of discovery of Australopithecus bahrelghazali (Abel) and in the Toros-Menalla fossiliferous area, TM 266 locality (16°15N, 17°29E) was the site of discovery of Sahelanthropus tchadensis (Toumaï). 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 (Ϸ7 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 bahrelghazali (Abel) with Australopithecus afarensis (Lucy). The 28 10 Be/ 9 Be ages obtained within the anthracotheriid unit containing Toumaï 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.
Proceedings of the National Academy of Sciences, 2012
Since its discovery, the Chauvet cave elaborate artwork called into question our understanding of... more Since its discovery, the Chauvet cave elaborate artwork called into question our understanding of Palaeolithic art evolution and challenged traditional chronological benchmarks Nature 413: . Chronological approaches revealing human presences in the cavity during the Aurignacian and the Gravettian are indeed still debated on the basis of stylistic criteria J Hum Evol 55:908-917]. The presented 36 Cl Cosmic Ray Exposure ages demonstrate that the cliff overhanging the Chauvet cave has collapsed several times since 29 ka until the sealing of the cavity entrance prohibited access to the cave at least 21 ka ago. Remarkably agreeing with the radiocarbon dates of the human and animal occupancy, this study confirms that the Chauvet cave paintings are the oldest and the most elaborate ever discovered, challenging our current knowledge of human cognitive evolution.
Geomorphology, 2012
The Rognier sackung, which extends NE-SW for more than 9 km, is a major gravitational morpho-stru... more The Rognier sackung, which extends NE-SW for more than 9 km, is a major gravitational morpho-structure located in the Western Alps. We used the 10 Be cosmic ray exposure dating method on 23 samples to unravel its history and better understand its genetic mechanism. We found that the average slip rate on sackung faults varies from 0.3 to 3.2 mm yr − 1 . Conjugate sackung faults are contemporaneous, in agreement with a model in which the whole mountain ridge is involved in the gravitational deformation (600 m thick). Multiple samples on single faults suggest that the development of this sackung started before 12 ka and that it is still active. We cannot exclude the possibility that the dissolution of the underlying Triassic evaporites participated in the sagging of Mt. Rognier. However, the age of this sackung and the presence of the Lauzière sackung on the other side of the Arcs valley support glacial erosion and debuttressing following the retreat of the valley glacier as the main causes of these large gravitational structures. The long and permanent activity of the Rognier sackung contrasts with that of the neighbouring Arcs sackung, which we previously dated using the same method and showed that it is a result of flexural toppling. Along with the proximity of the Rognier sackung to the Belledonne border active fault, its long history suggests that earthquake shaking contributed to maintain its activity. Additionally, two ages confirm that in the western Alps, rock glaciers formed mainly during the Younger Dryas. This study allowed the determination of the best sampling strategy for future CRE dating of these types of gravitational structures.
Chemical Geology, 2008
The high proportion of crystallized apatite forming the bones and teeth should theoretically allo... more The high proportion of crystallized apatite forming the bones and teeth should theoretically allow the use of fission track analysis to date vertebrate fossils when burying of the fossiliferous series did not subject them to temperatures exceeding 60°C. However several major obstacles arise such as the complexity of fossils' internal structures, diagenetic modifications and substitutions of the hydroxyapatite by other minerals, and massive U uptake or loss during diagenesis. In this work, those various problems are addressed combining optical microscope observation of the fossils, a systematic fission track analysis of the best samples, α and γ spectrometry and Secondary Ion Mass Spectrometry. Even if the problems caused by internal structures and mineral substitutions can be solved, U movements in and out of the fossils are generally too complex to allow fission track analysis dating of the fossils.
Proc. Natl. Acad. Sci. …, 2008
Ages were determined at two hominid localities from the Chad Basin in the Djurab Desert (Northern... more 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°00N, 18°53E) was the site of discovery of Australopithecus bahrelghazali (Abel) and in the Toros-Menalla fossiliferous area, TM 266 locality (16°15N, 17°29E) was the site of discovery of Sahelanthropus tchadensis (Toumaï). 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 (Ϸ7 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 bahrelghazali (Abel) with Australopithecus afarensis (Lucy). The 28 10 Be/ 9 Be ages obtained within the anthracotheriid unit containing Toumaï 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.
Abstracts by A. Lebatard
Since its discovery within a travertine quarry, the fragmentary cranium of the only known Turkish... more 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 ... more 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.
Chemical Geology, 2008
The high proportion of crystallized apatite forming the bones and teeth should theoretically allo... more The high proportion of crystallized apatite forming the bones and teeth should theoretically allow the use of fission track analysis to date vertebrate fossils when burying of the fossiliferous series did not subject them to temperatures exceeding 60°C. However several major obstacles arise such as the complexity of fossils' internal structures, diagenetic modifications and substitutions of the hydroxyapatite by other minerals, and massive U uptake or loss during diagenesis. In this work, those various problems are addressed combining optical microscope observation of the fossils, a systematic fission track analysis of the best samples, α and γ spectrometry and Secondary Ion Mass Spectrometry. Even if the problems caused by internal structures and mineral substitutions can be solved, U movements in and out of the fossils are generally too complex to allow fission track analysis dating of the fossils.
Ages were determined at two hominid localities from the Chad Basin in the Djurab Desert (Northern... more 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°00N, 18°53E) was the site of
discovery of Australopithecus bahrelghazali (Abel) and in the
Toros-Menalla fossiliferous area, TM 266 locality (16°15N, 17°29E)
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 ... more 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... more 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 D... more 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 travert... more 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.
by D. Bourlès, Régis Braucher, Marina Mosquera, Antonio Rosas, Andreu Ollé, A. Lebatard, Josep Maria Vergès, Maria Bennàsar, Isabel Cáceres, Ángel Carrancho, and Isabel Expósito Barea
PLoS ONE, 2014
The first arrivals of hominin populations into Eurasia during the Early Pleistocene are currently... more The first arrivals of hominin populations into Eurasia during the Early Pleistocene are currently considered to have occurred as short and poorly dated biological dispersions. Questions as to the tempo and mode of these early prehistoric settlements have given rise to debates concerning the taxonomic significance of the lithic assemblages, as trace fossils, and the geographical distribution of the technological traditions found in the Lower Palaeolithic record. Here, we report on the Barranc de la Boella site which has yielded a lithic assemblage dating to ,1 million years ago that includes large cutting tools (LCT). We argue that distinct technological traditions coexisted in the Iberian archaeological repertoires of the late Early Pleistocene age in a similar way to the earliest sub-Saharan African artefact assemblages. These differences between stone tool assemblages may be attributed to the different chronologies of hominin dispersal events. The archaeological record of Barranc de la Boella completes the geographical distribution of LCT assemblages across southern Eurasia during the EMPT (Early-Middle Pleistocene Transition, circa 942 to 641 kyr). Up to now, chronology of the earliest European LCT assemblages is based on the abundant Palaeolithic record found in terrace river sequences which have been dated to the end of the EMPT and later. However, the findings at Barranc de la Boella suggest that early LCT lithic assemblages appeared in the SW of Europe during earlier hominin dispersal episodes before the definitive colonization of temperate Eurasia took place.
Earth and Planetary Science Letters, 2010
The concentrations of atmospheric cosmogenic 10Be normalized to the solubilized fraction of its s... more 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.
PLoS ONE, 2014
The first arrivals of hominin populations into Eurasia during the Early Pleistocene are currently... more The first arrivals of hominin populations into Eurasia during the Early Pleistocene are currently considered to have occurred as short and poorly dated biological dispersions. Questions as to the tempo and mode of these early prehistoric settlements have given rise to debates concerning the taxonomic significance of the lithic assemblages, as trace fossils, and the geographical distribution of the technological traditions found in the Lower Palaeolithic record. Here, we report on the Barranc de la Boella site which has yielded a lithic assemblage dating to ,1 million years ago that includes large cutting tools (LCT). We argue that distinct technological traditions coexisted in the Iberian archaeological repertoires of the late Early Pleistocene age in a similar way to the earliest sub-Saharan African artefact assemblages. These differences between stone tool assemblages may be attributed to the different chronologies of hominin dispersal events. The archaeological record of Barranc de la Boella completes the geographical distribution of LCT assemblages across southern Eurasia during the EMPT (Early-Middle Pleistocene Transition, circa 942 to 641 kyr). Up to now, chronology of the earliest European LCT assemblages is based on the abundant Palaeolithic record found in terrace river sequences which have been dated to the end of the EMPT and later. However, the findings at Barranc de la Boella suggest that early LCT lithic assemblages appeared in the SW of Europe during earlier hominin dispersal episodes before the definitive colonization of temperate Eurasia took place.
Proceedings of the National Academy of Sciences, 2008
Ages were determined at two hominid localities from the Chad Basin in the Djurab Desert (Northern... more 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°00N, 18°53E) was the site of discovery of Australopithecus bahrelghazali (Abel) and in the Toros-Menalla fossiliferous area, TM 266 locality (16°15N, 17°29E) was the site of discovery of Sahelanthropus tchadensis (Toumaï). 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 (Ϸ7 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 bahrelghazali (Abel) with Australopithecus afarensis (Lucy). The 28 10 Be/ 9 Be ages obtained within the anthracotheriid unit containing Toumaï 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.
Proceedings of the National Academy of Sciences, 2012
Since its discovery, the Chauvet cave elaborate artwork called into question our understanding of... more Since its discovery, the Chauvet cave elaborate artwork called into question our understanding of Palaeolithic art evolution and challenged traditional chronological benchmarks Nature 413: . Chronological approaches revealing human presences in the cavity during the Aurignacian and the Gravettian are indeed still debated on the basis of stylistic criteria J Hum Evol 55:908-917]. The presented 36 Cl Cosmic Ray Exposure ages demonstrate that the cliff overhanging the Chauvet cave has collapsed several times since 29 ka until the sealing of the cavity entrance prohibited access to the cave at least 21 ka ago. Remarkably agreeing with the radiocarbon dates of the human and animal occupancy, this study confirms that the Chauvet cave paintings are the oldest and the most elaborate ever discovered, challenging our current knowledge of human cognitive evolution.
Geomorphology, 2012
The Rognier sackung, which extends NE-SW for more than 9 km, is a major gravitational morpho-stru... more The Rognier sackung, which extends NE-SW for more than 9 km, is a major gravitational morpho-structure located in the Western Alps. We used the 10 Be cosmic ray exposure dating method on 23 samples to unravel its history and better understand its genetic mechanism. We found that the average slip rate on sackung faults varies from 0.3 to 3.2 mm yr − 1 . Conjugate sackung faults are contemporaneous, in agreement with a model in which the whole mountain ridge is involved in the gravitational deformation (600 m thick). Multiple samples on single faults suggest that the development of this sackung started before 12 ka and that it is still active. We cannot exclude the possibility that the dissolution of the underlying Triassic evaporites participated in the sagging of Mt. Rognier. However, the age of this sackung and the presence of the Lauzière sackung on the other side of the Arcs valley support glacial erosion and debuttressing following the retreat of the valley glacier as the main causes of these large gravitational structures. The long and permanent activity of the Rognier sackung contrasts with that of the neighbouring Arcs sackung, which we previously dated using the same method and showed that it is a result of flexural toppling. Along with the proximity of the Rognier sackung to the Belledonne border active fault, its long history suggests that earthquake shaking contributed to maintain its activity. Additionally, two ages confirm that in the western Alps, rock glaciers formed mainly during the Younger Dryas. This study allowed the determination of the best sampling strategy for future CRE dating of these types of gravitational structures.
Chemical Geology, 2008
The high proportion of crystallized apatite forming the bones and teeth should theoretically allo... more The high proportion of crystallized apatite forming the bones and teeth should theoretically allow the use of fission track analysis to date vertebrate fossils when burying of the fossiliferous series did not subject them to temperatures exceeding 60°C. However several major obstacles arise such as the complexity of fossils' internal structures, diagenetic modifications and substitutions of the hydroxyapatite by other minerals, and massive U uptake or loss during diagenesis. In this work, those various problems are addressed combining optical microscope observation of the fossils, a systematic fission track analysis of the best samples, α and γ spectrometry and Secondary Ion Mass Spectrometry. Even if the problems caused by internal structures and mineral substitutions can be solved, U movements in and out of the fossils are generally too complex to allow fission track analysis dating of the fossils.
Proc. Natl. Acad. Sci. …, 2008
Ages were determined at two hominid localities from the Chad Basin in the Djurab Desert (Northern... more 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°00N, 18°53E) was the site of discovery of Australopithecus bahrelghazali (Abel) and in the Toros-Menalla fossiliferous area, TM 266 locality (16°15N, 17°29E) was the site of discovery of Sahelanthropus tchadensis (Toumaï). 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 (Ϸ7 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 bahrelghazali (Abel) with Australopithecus afarensis (Lucy). The 28 10 Be/ 9 Be ages obtained within the anthracotheriid unit containing Toumaï 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.