40Ar/(39)Ar dating of Chemeron Formation strata encompassing the site of hominid KNM-BC 1, Tugen Hills, Kenya.

A fossil hominid temporal bone (KNM-BC 1) from surface exposures at Baringo Paleontological Research Project site BPRP#2 in the Chemeron Formation outcropping in a tributary drainage of the Kapthurin River west of Lake Baringo, Kenya has been attributed to Homo sp. indet. K-feldspar phenocrysts from lapilli tuffs bracketing the inferred fossiliferous horizon yield single-crystal(40)Ar/(39)Ar ages of 2.456+/-0.006 and 2.393+/-0.013 Ma. These age determinations are supported by stratigraphically consistent ages on higher tuff horizons and from nearby sections. In addition, new(40)Ar/(39)Ar ages on tuffaceous units near the base and top of the formation along the Kapthurin River yield 3.19+/-0.03 and 1.60+/-0.05 Ma respectively. The base of the formation along the Kapthurin River is thus approximately 0.5 Ma younger than the uppermost Chemeron Formation strata exposed at Tabarin, 23 km to the north-northwest. The upper half of the formation along the Kapthurin River was deposited at an average rate of approximately 11 cm/ka, compared to 21-23 cm/ka at Tabarin.     

Tephrostratigraphy and the Acheulian to middle stone age transition in the Kapthurin Formation, Kenya.

Sites containing Acheulian, Sangoan, Fauresmith, and Middle Stone Age artefacts occur within and below the Bedded Tuff, a widespread volcaniclastic member of the Kapthurin Formation, Kenya. The Bedded Tuff eruptive complex consists of up to twelve tephra beds, intercalated sediments, and paleosols. Two pumiceous units, high in the Bedded Tuff sequence, have been dated by(40)Ar/(39)Ar, one to 235+/-2 ka (Deino & McBrearty, 2002, Journal of Human Evolution, 42, 185-210, cf. Tallon, 1978, Geological Background to Fossil Man, pp. 361-373, Scottish Academic Press), the other to 284+/-12 ka (Deino & McBrearty, 2001), the latter now providing a minimum age estimate for all underlying archaeological sites. Bedded Tuff outcrops are correlated through field stratigraphic and electron microprobe geochemical analyses of individual beds. Bedded Tuff units show increasingly evolved composition through the stratigraphic succession, indicating that the beds are the product of intermittent eruption of a single differentiating magma system, and the chemical signatures of these beds permit the chronological ordering of archaeological sites. Our results indicate that the transition to Middle Stone Age technology occurred prior to 285 ka in this region of East Africa. The interstratification of sites containing Acheulian, Sangoan, Fauresmith, and Middle Stone Age artefacts suggests that these technologies were contemporary in a single depositional basin over the duration of the transition.     

40Ar/39Ar geochronology and paleomagnetic stratigraphy of the Lukeino and lower Chemeron Formations at Tabarin and Kapcheberek,Tugen Hills,Kenya

⁴⁰Ar/³⁹Ar single-crystal laser-fusion dating, K–Ar dating, and paleomagnetic reversal stratigraphy have been used to determine the chronostratigraphy of the Kabarnet Trachyte, Lukeino Formation, Kaparaina Basalt Formation, and Chemeron Formation at the sites of Kapcheberek (BPRP#77) and Tabarin (BPRP#77) in the Tugen Hills, Kenya. The succession ranges in age from 6·56–3·8 Ma. The upper Lukeino Formation at Kapcherberek, including the fauna from the site BPRP#76, was deposited during chron C3r and can be constrained to the interval 5·88–5·72 Ma. The Chemeron Formation at Tabarin includes at the base an ignimbrite and associated basal air-fall tuff with a combined age of 5·31±0·03 Ma. Sedimentary and volcaniclastic rocks of the Chemeron Formation which unconformably overlie the ignimbrite record chrons C3n.2n through C2Ar. The combined⁴⁰Ar/³⁹Ar and paleomagnetic data constrain the age of this sequence to 4·63–3·837 Ma. The age of the Tabarin mandible fragment (KNM-TH 13150) and associated fauna at site BPRP#77 in the Chemeron Formation is 4·48–4·41 Ma, marginally older than similar early hominids from Aramis, Ethiopia. Basin subsidence appears to be defining an overall accumulation rate of about 17 cm/ka over the 2·7 Ma represented at Tabarin and Kapcheberek, despite episodes of rapid accumulation and hiatuses.     

Ar/Ar dating, paleomagnetism, and tephrochemistry of Pliocene strata of the hominid-bearing Woranso-Mille area, west-central Afar Rift, Ethiopia

⁴⁰Ar/³⁹Ar dating of tuffs and mafic lavas, tephra geochemistry, and paleomagnetic reversal stratigraphy have been used to establish the chronostratigraphy of the Pliocene hominid-bearing fossiliferous succession at Woranso-Mille, a paleontological study area in the western part of the central Afar region of Ethiopia. The succession in the northwestern part of the study area ranges in ⁴⁰Ar/³⁹Ar age from 3.82-3.570 Ma, encompassed by paleomagnetic subchron C2Ar (4.187-3.596 Ma). One of the major tuff units, locally named the Kilaytoli tuff, is correlative on the basis of age and geochemistry to the Lokochot Tuff of the Turkana Basin. A hominid partial skeleton (KSD-VP-1) was found in strata whose precise stratigraphic position and age is still under investigation, but is believed to correspond to the later part of this interval. Woranso-Mille fills a significant gap in the fossil record of northeastern Africa at the time of the lower to middle Pliocene transition, when many extant species lineages of African fauna were established.     

Revised stratigraphy of Area 123, Koobi Fora, Kenya, and new age estimates of its fossil mammals, including hominins

Recent geologic study shows that all hominins and nearly all other published mammalian fossils from Paleontological Collection Area 123, Koobi Fora, Kenya, derive from levels between the KBS Tuff (1.87+/-0.02 Ma) and the Lower Ileret Tuff (1.53+/-0.01 Ma). More specifically, the fossils derive from 53 m of section below the Lower Ileret Tuff, an interval in which beds vary markedly laterally, especially those units containing molluscs and algal stromatolites. The upper Burgi Member (approximately 2.00-1.87 Ma) crops out only in the southwestern part of Area 123. Adjacent Area 110 contains larger exposures of the member, and there the KBS Tuff is preserved as an airfall ash in lacustrine deposits and also as a fluvially redeposited ash. We observed no mammalian fossils in situ in this member in Area 123, but surface specimens have been documented in some monographic treatments. Fossil hominins from Area 123 were attributed to strata above the KBS Tuff in the 1970s, but later they were assigned to strata below the KBS Tuff (now called the upper Burgi Member). This study definitively places the Area 123 hominins in the KBS Member. Most of these hominins are between 1.60 and 1.65 myr in age, but the youngest may date to only 1.53 Ma, and the oldest, to 1.75 Ma. All are 0.15-0.30 myr younger than previously estimated. The new age estimates, in conjunction with published taxonomic attributions of fossils, suggest that at least two species of Homo coexisted in the region along with A. boisei until at least 1.65 Ma. Comparison of crania KNM-ER 1813 and KNM-ER 1470, which were believed to be of comparable age, is at the focus of the debate over whether Homo habilis sensu lato is in fact composed of two species: Homo habilis and Homo rudolfensis. These two crania are separated in time by approximately 0.25 myr, and therefore, arguments for their conspecificity no longer need to confront the issue of unusually high contemporaneous variation within a single species.     

(40)Ar/(39)Ar dating of Bed I, Olduvai Gorge, Tanzania, and the chronology of early Pleistocene climate change

⁴⁰Ar/³⁹Ar dating of tuffs and lavas of the late Pleistocene volcanic and sedimentary sequence of Olduvai Gorge, north-central Tanzania, provides the basis for a revision of Bed I chronostratigraphy. Bed I extends from immediately above the Naabi Ignimbrite at 2.038 ± 0.005 Ma to Tuff IF at 1.803 ± 0.002 Ma. Tuff IB, a prominent widespread marker tuff in the basin and a key to understanding hominin evolutionary chronologies and paleoclimate histories, has an age of 1.848 ± 0.003 Ma. The largest lake expansion event in the closed Olduvai lake basin during Bed I times encompassed the episode of eruption and emplacement of this tuff. This lake event is nearly coincident with the maximum precessional insolation peak of the entire Bed I/Lower Bed II interval, calculated from an astronomical model of the boreal summer orbital insolation time-series. The succeeding precessional peak also apparently coincides with the next youngest expansion of paleo-Lake Olduvai. The extreme wet/dry climate shifts seen in the upper part of Bed I occur during an Earth-orbital eccentricity maximum, similar to episodic lake expansions documented elsewhere in the East African Rift during the Neogene.     

Sapropels and the age of hominins Omo I and II, Kibish, Ethiopia

The provenance and age of two Homo sapiens fossils (Omo I and Omo II) from the Kibish Formation in southern Ethiopia have been much debated. Here we confirm that Omo I and the somewhat more primitive-looking Omo II calvariae are from similar stratigraphic levels in Member I of the Kibish Formation. Based on (40)Ar/(39)Ar age measurements on alkali feldspar crystals from pumice clasts in the Nakaa'kire Tuff, a tuffaceous bed in Member I just below the hominin levels, we place an older limit of 198+/-14ka (weighted mean age=196+/-2ka) for the hominins. A younger limit of 104+/-7ka (weighted mean age=104+/-1ka) is provided by feldspars separated from pumice clasts in the Aliyo Tuff in Member III. Geological evidence indicates rapid deposition of each member of the Kibish Formation, concurrent with deposition of sapropels in the Mediterranean Sea. The (40)Ar/(39)Ar age measurements, together with correlations with sapropels, indicate that the hominin fossils are close in age to the older limit. Our preferred estimate of the age of the hominins is 195+/-5ka, making them the earliest well-dated anatomically modern humans yet described.     

Extending the chronology of deposits at Blombos Cave, South Africa, back to 140 ka using optical dating of single and multiple grains of quartz

Optically stimulated luminescence (OSL) measurements are reported for both single aliquots (of two different sizes) and single grains of quartz from deposits within Blombos Cave. Ages have been obtained for six sediments from the Middle Stone Age (MSA) occupation levels and for two sterile sands, one underlying the archaeological sediment and one overlying the Later Stone Age occupation levels. The ages for the archaeological sediments were obtained from single-grain measurements that enabled unrepresentative grains to be rejected. The MSA occupation levels have ages that, within error limits, are in stratigraphic order and fall between the OSL age for the oldest dune sand (143.2+/-5.5 ka) and a previously published OSL age for the sterile sand ( approximately 70 ka) that separates the Middle and Later Stone Age deposits. The earliest MSA archaeological phase, M3, from where fragments of ochre were found as well as human teeth, is dated to 98.9+/-4.5 ka, coinciding with the sea-level high of oxygen isotope substage 5c. The cave then appears to be unoccupied until oxygen isotope substage 5a on the basis of four OSL ages for archaeological phase M2, ranging from 84.6+/-5.8 to 76.8+/-3.1 ka; these levels contained large hearths and bone tools. An age of 72.7+/-3.1 ka was obtained for the final MSA archaeological phase, M1, from which deliberately engraved ochre and shell beads were recovered along with bifacial stone points. We conclude that the periods of occupation were determined by changes in sea level, with abundant sources of seafood available in times of high sea level and with the cave being closed by the accumulation of large dunes during periods of low sea level, such as during oxygen isotope stages 4 and 6.     

Human remains from Valdegoba Cave (Huérmeces, Burgos, Spain).

Systematic excavations, begun in 1987, at the Valdegoba cave site in northern Spain have yielded the remains of five individuals associated with a Middle Paleolithic stone tool technology and Pleistocene fauna. A fragmentary mandible of an adolescent (VB1), preserving nearly a full set of teeth, exhibits a symphyseal tubercle and slight incurvatio mandibulae anterior on the external symphysis. Both the superior and inferior transverse tori are present on the internal aspect. A second individual (VB2) is represented by a set of ten deciduous teeth consistent with an age at death of 6-9 months. A proximal manual phalanx (VB3) displays a relatively broad head, a characteristic which is found in both Neandertals, as well as European Middle Pleistocene hominids. VB4 is a fourth metatarsal that lacks the distal epiphysis, indicating it comes from an adolescent individual, and has a relatively high robusticity index. Finally, VB5 is a fifth metatarsal of an adult. The VB1 mandible shows a combination of archaic characteristics as well as more specific Neandertal morphological traits. The VB2 deciduous teeth are very small, and both the metrics and morphology seem more consistent with a modern human classification. The postcranial elements are undiagnostic, U-Th dating has provided an age of >350 ka for the base of the sequence and a date of <73.2+/-5 ka for level 7, near the top. Faunal analysis and radiometric dates from other nearby Mousterian sites suggests that the Valdegoba site is correlative with oxygen isotope stages 3-6 on the Iberian peninsula, and an Upper Pleistocene age for the Valdegoba hominids seems most reasonable.     

Hominid cranial remains from upper Pleistocene deposits at Aduma, Middle Awash, Ethiopia

The Upper Pleistocene localities of Aduma and Bouri have yielded hominid fossils and extensive Middle Stone Age (MSA) archaeological assemblages. The vertebrate fossils recovered include parts of four hominid crania from Aduma and a complete right parietal from Bouri. Archaeological associations and radiometric techniques suggest an Upper Pleistocene age for these hominids. The more complete cranium from Aduma (ADU-VP-1/3) comprises most of the parietals, the occipital, and part of the frontal. This cranium is compared to late Middle and Upper Pleistocene hominid crania from Africa and the Middle East. The Aduma cranium shows a mosaic of cranial features shared with "premodern" and anatomically modern Homo sapiens. However, the posterior and lateral cranial dimensions, and most of its anatomy, are centered among modern humans and resemble specimens from Omo, Skhul, and Qafzeh. As a result, the Aduma and Bouri Upper Pleistocene hominids are assigned to anatomically modern Homo sapiens.     

Turkana Basin-Middle Awash Valley correlations and the age of the Sagantole and Hadar Formations

The Moiti, Lomogol and Wargolo Tuffs of the Turkana Basin correlate with similar layers in the Sagantole Formation exposed in the Middle Awash Valley, Ethiopia. These correlations demonstrate that the tephrostratigraphy of the Turkana Basin can be applied to the Middle Awash Valley. Consideration of our analyses together with previous analyses shows that more volcanic ash layers are present in the Sagantole Formation than have been reported and also that the proposed correlation of VT-2 between Bodo and Belohdelie is incorrect. In addition, the correlations suggest that the age of the Cindery Tuff of the Sagntole Formation is about 3·8 Ma, at the young end of the range proposed earlier (3·8–4·0 Ma). This implies that the hominid skull fragments from the Sagantole Formation are 3·8–3·9 Ma. The upper part of the Sagantole Formation contains the Lomogol Tuff (ca. 3·6 Ma). Because the Sagantole Formation underlies the Hadar Formation, the base of the Hadar Formation can be no older than 3·8 Ma and is probably younger than 3·6 Ma, in agreement with correlation of the Tulu Bor (ca. 3·35 Ma) and Sidi Hakoma Tuffs. As all hominid fossils presently known from the Hadar Formation are younger than the Sidi Hakoma Tuff, they must be younger than 3·35 Ma. This estimate agrees with faunal evidence from the lower part of the Hadar Formation, and allows placement of hominids from Laetoli, the Middle Awash Valley and the Turkana Basin in temporal order.     

Middle Stone Age Ochre Processing and Behavioural Complexity in the Horn of Africa: Evidence from Porc-Epic Cave,Dire Dawa,Ethiopia

Ochre is a common feature at Middle Stone Age (MSA) sites and has often been interpreted as a proxy for the origin of modern behaviour. However, few ochre processing tools, ochre containers, and ochre-stained artefacts from MSA contexts have been studied in detail within a theoretical framework aimed at inferring the technical steps involved in the acquisition, production and use of these artefacts. Here we analyse 21 ochre processing tools, i.e. upper and lower grindstones, and two ochre-stained artefacts from the MSA layers of Porc-Epic Cave, Dire Dawa, Ethiopia, dated to ca. 40 cal kyr BP. These tools, and a large proportion of the 4213 ochre fragments found at the site, were concentrated in an area devoted to ochre processing. Lower grindstones are made of a variety of raw materials, some of which are not locally available. Traces of use indicate that different techniques were employed to process ochre. Optical microscopy, XRD, μ-Raman spectroscopy, and SEM-EDS analyses of residues preserved on worn areas of artefacts show that different types of ferruginous rocks were processed in order to produce ochre powder of different coarseness and shades. A round stone bearing no traces of having been used to process ochre is half covered with residues as if it had been dipped in a liquid ochered medium to paint the object or to use it as a stamp to apply pigment to a soft material. We argue that the ochre reduction sequences identified at Porc-Epic Cave reflect a high degree of behavioural complexity, and represent ochre use, which was probably devoted to a variety of functions.     

High-precision Ar/Ar age for the Jehol Biota

Abundant fossils of the terrestrial Jehol Biota, including plants, insects, dinosaurs, birds, mammals and freshwater invertebrates, were discovered from the Yixian Formation and the overlying Jiufotang Formation in Inner Mongolia, Hebei Province and Liaoning Province, northeastern China. Because of the exceptional preservation of fossils, the Jehol Biota is one of the most important Mesozoic lagerstätten and is referred to as a “Mesozoic Pompeii”. The Jehol Biota has provided a rare opportunity to address questions about the origin of birds, the evolution of feathers and flight, the early diversification of angiosperms and the timing of placental mammal radiation. Six tuff samples and two basalt samples collected from the Tuchengzi, the Yixian and the Jiufotang formations near the classic outcrops in western Liaoning, NE China yielded high-precision ⁴⁰Ar/³⁹Ar ages. We obtain an age of 129.7 ± 0.5 Ma for a basaltic lava from the bottom of the Yixian Formation and an age of 122.1 ± 0.3 Ma for a tuff from the lowermost part of the overlying Jiufotang Formation. Our age results provide an age calibration of the whole Yixian Formation and show that the whole formation was deposited entirely within Early Cretaceous time over an interval of ~ 7 Ma.     

Paleoanthropology of the Kibish Formation, southern Ethiopia: Introduction

Cranial and skeletal remains of modern humans, Homo sapiens, were discovered in the Kibish Formation in 1967 by a team from the Kenya National Museums directed by Richard Leakey. Omo I, from Kamoya's Hominid Site (KHS), consists of much of a skeleton, including most of the cranial vault, parts of the face and mandible, and many postcranial elements. Omo II, from Paul's Hominid Site (PHS), is a virtually complete calvaria. Only a limited fauna and a few stone artifacts attributed to the Middle Stone Age were recovered in conjunction with the fossil hominids. The available dating techniques suggested a very early age, over 100 ka, for Member I, from which the Omo I and Omo II fossils were recovered. However, in subsequent decades, the reliability of the dates and the provenance of the Kibish hominids were repeatedly questioned. The papers in this volume provide a detailed stratigraphic analysis of the Kibish Formation and a series of new radiometric dates that indicate an age of 196 +/- 2 ka for Member I and 104 +/- 1 for Member III, confirming the antiquity of the lower parts of the Kibish Formation and, in turn, the fossils from Member I. Studies of the postcranial remains of Omo I indicate an overall modern human morphology with a number of primitive features. Studies of an extensive lithic record from Members I and III indicate a Middle Stone Age technology comparable to assemblages of similar age elsewhere in Ethiopia. Studies of the mammalian, avian, and fish faunas indicate overall similarities to those found in the region today, with a few distinctive differences.     

First occurrence of early Homo in the Nachukui Formation (West Turkana, Kenya) at 2.3-2.4 Myr

Cognitive abilities and techno-economic behaviours of hominids in the time period between 2.6-2.3 Myr have become increasingly well-documented. This time period corresponds to the oldest evidence for stone tools at Gona (Kada Gona, West Gona, EG 10-12, OGS 6-7), Hadar (AL 666), lower Omo valley (Ftji1, 2 & 5, Omo 57, Omo 123) in Ethiopia, and West Turkana (Lokalalei sites -LA1 & LA2C-) in Kenya. In 2002 a new palaeoanthropological site (LA1alpha), 100 meters south of the LA1 archaeological site, produced a first right lower molar of a juvenile hominid (KNM-WT 42718). The relative small size of the crown, its marked MD elongation and BL reduction, the relative position of the cusps, the lack of a C6 and the mild expression of a protostylid, reinforced by metrical analyses, demonstrate the distinctiveness of this tooth compared with Australopithecus afarensis, A. anamensis, A. africanus and Paranthropus boisei, and its similarity to early Homo. The LA1alpha site lies 2.2 m above the Ekalalei Tuff which is slightly younger than Tuff F dated to 2.34+/-0.04 Myr. This juvenile specimen represents the oldest occurrence of the genus Homo in West Turkana.     

Geochronology of the Turkana depression of northern Kenya and southern Ethiopia

Mesozoic and Cenozoic sedimentary rocks in the Turkana Depression of northern Kenya and southern Ethiopia rest on basement rocks that yield K/Ar cooling ages between 433 and 522 Ma. Proven Cretaceous strata are exposed in Lokitaung Gorge in northwest Kenya. Eocene basalts and rhyolites in Lokitaung Gorge, the Nabwal Hills, and at Kangamajoj, date between 34 and 36 Ma, recording the earliest volcanism in the region. Oligocene volcanic rocks, with associated fossiliferous sedimentary strata at Eragaleit, Nakwai, and Lokone, all west of Lake Turkana, are 23 to 28 Ma old, as is the Langaria Formation east of Lake Turkana. Lower and Middle Miocene volcanic and sedimentary sequences are present both east and west of Lake Turkana, where ages from 17.9 to 9.1 Ma have been measured at many levels. Upper Miocene strata are presently known only at Lothagam, with ages ranging from 7.4 to 6.5 Ma. Deposition of Pliocene strata of the Omo Group begins in the Omo-Turkana, Kerio, and South Turkana basins -4.3 Ma ago and continues in parts of those basins until nearly the present time, but with some gaps. These strata are linked through volcanic ash correlations at many levels, as are Pleistocene strata of the Omo Group (principally the Shungura, Koobi Fora, and Nachukui formations). (40) Ar/(39) Ar dates on many volcanic ash layers within the Omo Group, supplemented by K/Ar ages on intercalated basalts and paleomagnetic polarity stratigraphy, provide excellent age control from 4.2 to 0.75 Ma, although there is a gap in the record between -1 Ma and 0.8 Ma. Members I to III of the Kibish Formation in the lower Omo Valley record deposition between 0.2 and 0.1 Ma ago; Member IV, correlative with the Galana Boi Formation, was deposited principally between 12 and 7 ka BP.     

A consideration of some major topics concerning Old WorldMiocene Mammalian chronology,migrations and paleogeography

The authors of this note met to discuss the chronology of certain Miocene biologic events and their implications concerning palaeogeographic reconstructions. Two topics in particular were examined. The first was that the collision of the Afro-Arabian Plate into mainland Asia appears to have had a gradual effect on the mammalian and marine faunas. The marine evidence suggests a progressive diminution in exchanges between the Mediterranean Sea and the Indian Ocean from the Chattian/Aquitanian boundary onwards (Adams et alii 1983) whereas the continental mammalian faunas do not indicate the occurrence of faunal interchanges prior to the Burdigalian. The period between 18 and 20 Ma seems to be the key moment for the establishment of intercontinental pathways permitting faunal exchanges between the two land masses.The second subject examined concerned the «Hippariondatum. Analysis of available geochronological evidence and biostratigraphical correlations do not confirm the date of 12.5 Ma attributed to the earliest known Mediterranean Hipparions. On the contrary, it seems that the radiometric dates obtained from tuffs at Höwenegg (Germany) and Bou Hanifia (Algeria) on which this early date was founded, are not closely associated with the fossils they purport to date. New radiometric dates allied with magneto- and biostratigraphy allow us to suggest an age about 11.5 Ma to the earliest records of Hipparion in Europe and North Africa.     

Récentes découvertes de restes d'Hominidés fossiles en Chine du Sud

After the discovery of the controversial hominids and artefacts at the Longgupo site, three Early Pleistocene sites in the southern valleys of the Changjiang (Yangtze) were excavated from 1998 to 2000 in order to test the hypothesis that the hominids exist in China before 2 Ma. Three cheek teeth of Meganthropus palaeojavanicus, more than six hundreds pieces of artefacts of Mode 1 technology and thousands pieces of mammal fossils of Villafranchian age were unearthed in situ at the Longgudong Site in Hubei Province. More than 120 pieces of artefacts of Mode 1 technology and seven thousands pieces of mammal fossils of Villafranchian age were unearthed in situ at the Renzidong Site in Anhui Province. Although no new materials of hominids and artefacts were unearthed at the Yuanmou Man Site at Danawu in Yunnan Province, new materials of mammalian fauna confirm the horizon yielding the Yuanmou Man fossils is of the Early Pleistocene. These new discoveries imply that the appearance of hominids in China is very likely before 2 Ma. If the new report of 3 Ma artefact from Yuxian of the Nihewan Basin in northern China can be confirmed, it will be a strong support for the Continuity Theory.     

Examining time trends in the Oldowan technology at Beds I and II,Olduvai Gorge

The lithic analysis of the Bed I and II assemblages from Olduvai Gorge reveals both static and dynamic time trends in early hominids' technology from 1.8 to 1.2 m.y.a. The Bed I Oldowan (1.87-1.75 m.y.a.) is characterized by the least effort strategy in terms of raw material exploitation and tool production. The inclusion of new raw material, chert, for toolmaking in the following Developed Oldowan A (DOA, 1.65-1.53 m.y.a.) facilitated more distinctive and variable flaking strategies depending on the kind of raw materials. The unique characters of DOA are explainable by this raw material factor, rather than technological development of hominids. The disappearance of chert in the subsequent Developed Oldowan B and Acheulian (1.53-1.2 m.y.a.) necessitated a shift in tool production strategy more similar to that of Bed I Oldowan than DOA. However, the evidence suggests that Bed II hominids might have been more skillful toolmakers, intensive tool-users, and engaged in more active transport of stone tools than the Bed I predecessors. Koobi Fora hominids maintained a more static tool-using behavior than their Olduvai counterparts due mainly to a stable supply of raw materials. They differed from Olduvai hominids in terms of less battering of cores, consistent transport behavior, and few productions of side-struck flakes, indicating a regional variation of toolmaking and using practice. However, they shared with Olduvai hominids a temporal trend toward the production of larger flakes from larger cores after 1.6 m.y.a. Increased intake of animal resources and the expansion of ranging area of Homo ergaster would have led to the development of technological organization. Technological changes in the Oldowan industry are attested at Olduvai Gorge, Koobi Fora, and Sterkfontein, suggesting that it was a pan-African synchronous phenomenon, beginning at 1.5 m.y.a.     

Palaeomagnetic analysis of the Sterkfontein palaeocave deposits: implications for the age of the hominin fossils and stone tool industries

Palaeomagnetic analysis was conducted on speleothems from Members 1-5 at Sterkfontein Cave, South Africa. Palaeomagnetic analysis of siltstone and speleothem from the bulk of Member 4 indicate a reversed magnetic polarity that dates the deposits and its Australopithecus africanus fossils to between 2.58 and ∼2.16 Ma. Further confirmation of this age comes in the form of two short normal polarity events correlated to the Rèunion (∼2.16 Ma) and Huckleberry Ridge (∼2.05 Ma) events in speleothem capping the bulk of Member 4 and coeval with deposition of the final phase of Member 4, including A. africanus fossil Sts 5. At ∼2.16-2.05 Ma, Sts 5 is the youngest representative of A. africanus yet discovered. Palaeomagnetic analysis of the Silberberg Grotto deposits identifies a single short geomagnetic field event in flowstone overlying the StW 573 Australopithecus fossil, which is suggested to represent the Rèunion event at ∼2.16 Ma. This further supports the uranium lead age estimates of 2.3-2.2 Ma for the StW 573 fossil. Based on a reversed polarity for the deposits below the skeleton it cannot be older than 2.58 Ma. If StW 573 is considered to be a second species of Australopithecus then this indicates that two species of Australopithecus are present at Sterkfontein between 2.6 and 2.0 Ma. All of the Member 5 deposits date to less than 1.8 Ma based on a comparison of palaeomagnetic, faunal, and electron spin resonance age estimates. The StW 53 fossil bearing infill (M5A) is intermediate in age between Member 4 and the rest of Member 5 (B-C) at around 1.78-1.49 Ma. The rest of Member 5 (B-C) containing Oldowan and Acheulian stone tools and Homo and Paranthropus fossils was deposited gradually between 1.40 and 1.07 Ma, much younger than previously suggested.