Bone breccias, bone dumps, and sedimentary sequences of the western Limeworks, Makapansgat, South Africa

The sediments in the western side of the Makapansgat Limeworks were either precipitated as speleothems, represented in the earlier massive deposits, or were deposited as coarsening clastic sediments, mainly representing later deposits. Between the earlier deposits and the main sedimentary phase, the stratigraphic sequence was inverted twice to a considerable height by the unusual deposition of subaqueous speleothem. Bone-bearing deposits, including the Main Quarry Bone Breccia and the well-known Grey Breccia belong, in time, to the lower part of the clastic deposits called the Red Silts. Australopith fossils have been found in the Grey Breccia dumped material and, in situ, from the dolomite clast breccia on the Main Quarry entrance buttress. Whatever the problems may be in provenancing some of the material from the Limeworks dumps, there is no doubt that the three rows of blocks on the southern side of the dumps belong to the Grey Breccia, and other rows contain red sediment sufficient for them to be safely associated with the Red Silts. There is no reason why this material should not be prepared with confidence as to its stratigraphic provenance. In any case, stratigraphic evidence, presented here, shows that there is little difference in time between the deposition of the bone-bearing breccias.     

Stratigraphy, artefact industries and hominid associations for Sterkfontein, member 5

A revised stratigraphy for the early hominid site of Sterkfontein (Gauteng Province, South Africa) reveals a complex distribution of infills in the main excavation area between 2.8 and 1.4 m.y.a, as well as deposits dating to the mid to late Pleistocene. New research now shows that the Member 4 australopithecine breccia (2.8-2.6 Ma) extends further west than was previously thought, while a late phase of Member 4 is recognized in a southern area. The artefact-bearing breccias were defined sedimentologically as Member 5, but one supposed part of these younger breccias, the StW 53 infill, lacks in situ stone tools, although it does appear to post-date 2.6 Ma when artefacts first appear in the archaeological record. The StW 53 hominid, previously referred to Homo habilis, is here argued to be Australopithecus. The first artefact-bearing breccia of Member 5 is the Oldowan Infill, estimated at 2-1.7 Ma. It occupies a restricted distribution in Member 5 east and contains an expedient, flake-based tool industry associated with a few fossils of Paranthropos robustus. An enlarged cave opening subsequently admitted one or more Early Acheulean infills associated in Member 5 west with Homo ergaster. The artefacts attest to a larger site accumulation between ca. 1.7 and 1.4 Ma, with more intensive use of quartzite over quartz and a subtle but important shift to large flakes and heavier-duty tools. The available information on palaeoenvironments is summarized, showing an overall change from tropical to sub-tropical gallery forest, forest fringe and woodland conditions in Member 4 to more open woodland and grassland habitats in the later units, but with suggestions of a wet localized topography in the Paranthropus -bearing Oldowan Infill.     

Newly discovered fossil- and artifact-bearing deposits, uranium-series ages, and Plio-Pleistocene hominids at Swartkrans Cave, South Africa

We report on new research at Swartkrans Cave, South Africa, that provides evidence of two previously unrealized artifact- and fossil-bearing deposits. These deposits underlie a speleothem dated by the uranium-thorium disequilibrium technique to 110,000 ± 1,980 years old, the first tightly constrained, geochronological date available for the site. Recovered fauna from the two underlying deposits—including, prominently, the dental remains of Paranthropus (Australopithecus) robustus from the uppermost layer (Talus Cone Deposit)—indicate a significantly older, late Pliocene or early Pleistocene age for these units. The lowest unit (LB East Extension) is inferred to be an eastward extension of the well-known Lower Bank of Member 1, the earliest surviving infill represented at the site. The date acquired from the speleothem also sets the maximum age of a rich Middle Stone Age lithic assemblage.     

Middle Triassic basin evolution and stratigraphy in the Carnic Alps (Austria)

Summary A local intraplatform basin developed in the Gartnerkofel-Zielkofel area of the Carnic Alps (southern Carinthia, Austria) during the Middle Triassic (Ladinian). This basin was filled with a transgressive basinal sequence composed of the Uggowitz Formation and overlying Buchenstein Formation. At the northwestern slope of the Gartnerkofel, the platform carbonates of the Schlern Dolomite interfinger with the Buchenstein Formation, causing the formation of two depositional sequences. The Uggowitz Formation consists of the Uggowitz Breccia and the Kühweg Member. Sediments of the Uggowitz Breccia were formed by different types of gravity induced processes. The Kühweg Member is a thin sequence of silt-and fine-grained sandstones which were deposited in a slope to basin margin environment by turbidity currents. The overlying Buchenstein Formation consists of hemipelagic to pelagic limestones of Fassanian age with intercalated pyroclastic rocks (Pietra verde). Nodular limestones were deposited under slow rates of accumulation during a relative sea-level highstand. The uppermost Buchenstein Formation is composed of hemipelagic limestone beds with intercalated graded calcarenites and breccias of platform-derived debris, showing characteristics features of a fore-reef slope of the prograding Schlern Dolomite. Uggowitz Formation and basal Buchenstein Formation are interpreted as a transgressive systems tract, nodular limestones from the middle part of the Buchenstein Formation mark an early highstand systems tract, forereef slope sediments of the upper Buchenstein Formation formed during the beginning regression of a late highstand systems tract, the basal part of the overlying Schlern Dolomite probably reflects a lowstand systems tract. The intercalated bedded limestone facies within the Schlern Dolomite is characterized by large, platform derived blocks, slump structures, breccia beds, graded calcarenites and hemipelagic limestones indicating a forereef slope environent. This intercalated facies belongs to the Buchenstein Formation and interfingers with the Schlern Dolomite. Conodonts from this intercalated slope facies point to Late Fassanian age. Therefore, the two Middle Triassic depositional sequences of the Gartnerkofel area can be correlated with the depositional sequences ‘Ladinian 1’ and ‘Ladinian 2’ of the Dolomites, proposed byDe Zanche et al. (1993). A brief comparison with the basinal sequences of similar age of the karawanken Mountains and the Carnia is presented.     

Carbonate breccias in the lower-middle Ordovician Maggol Limestone (Taebacksan Basin,South Korea): Implications for regional tectonism

Summary Carbonate breccias occur sporadically in the Lower-Middle Ordovician Maggol Limestone exposed in the Taebacksan Basin, South Korea. These carbonate breccias have been previously interpreted as intraformational or fault breccias. Thus, little attention has been focused on tectonic and stratigraphic significance of these breccias. This study, however, indicates that the majority of these breccias are solution-collapse breccias, which are causally linked to paleokarstification. Carbonate facies analysis in conjunction with conodont biostratigraphy suggests that an overall regression toward the top of the Maggol Limestone probably culminated in subaerial exposure of platform carbonates during the early Middle Ordovician. Extensive subaerial exposure of platform carbonates resulted in paleokarst-related solution-collapse breccias in the upper maggol Limestone. This subaerial exposure event is manifested as a major paleokarst unconformity elsewhere beneath the Middle Ordovician sequence, most notably North America and North China. Due to its global extent, the early Middle ordovician paleokarst unconformity (‘the Sauk-Tippecanoe sequence boundary’) has been viewed as a product of second-order eustatic sea level drop during the early Middle Ordovician. Although we recognizes a paleokarst breccia zone in the upper Maggol Limestone beneath the Middle Ordovician sequence, the early Middle Ordovician sequence boundary appears to be a conformable transgressive surface or a drowning unconformity, rather than a major paleokarst unconformity. The paleokarst breccia zone in the upper Maggol Limestone is represented by a thinning-upward stack of exposure-capped tidal flat-dominated cycles that are closely associated with multiple occurrences of paleokarst-related solution-collapse breccias. The paleokarst breccia zone in the upper Maggol Limestone was a likely consequence of repeated high-frequency sea level fluctuations of fourth- and fifth-order superimposed on a second-and third-order eustatic fall in sea level that was less than the rate of tectonic subsidence across the platform. It suggests that second- and thirdorder eustatic sea level drop may have been significantly tempered by substantial tectonic subsidence near the end of maggol deposition. The tectonic subsidence in the basin is also evidenced by the occurrence of coeval off-platform lowstand siliciclastic quarzite lenses as well as debris flow carbonate breccias. With the continued tectonic subsidence, subsequent rise in the eustatic cycle caused drowning and deep flooding of carbonate platform, forming a conformable transgressive surface or a drowning unconformity on the top of the paleokarst breccia zone. This tectonic implication contrasts notably with the slowly subsiding carbonate platform model for the Taebacksan Basin as previously intepreted. Here we propose that the Taebacksan Basin evolved from a slowly subsiding carbonate platform to a rapidly subsiding intracontinental rift basin during the early Middle Ordovician. This study also provides a good example that the falling part of the eustatic sea-level cycle may not produce a significant event at all in a rapidly subsiding basin where the rate of eustatic fall always remained lower than the rate of subsidence.     

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.     

Karst development,breccias history,and mammalian assemblages in Southeast Asia: A brief review

Karst processes typically occur in carbonate rocks, such as limestone or dolomite. They occur all over the world everywhere where carbonate rocks are exposed and submitted to rain and/or water circulation. The karstification of carbonate rocks-bearing landscapes leads to a variety of surface and subsurface features. In tropical and sub-tropical areas as it is the case in Southeast Asia, the mature karst landscapes display a typical morphology called tower karst. Beneath the surface, the complex underground drainage systems contribute to an extensive network of caves and caverns, which may be filled with breccia. The history of sedimentary cave infilling is often complicated due to alternating cycles of infilling/removing phases through time, driven by climate/tectonic/eustatic changes. We present results from our research in Vietnam and Laos. We emphasise that both modern and fossil alluvial terraces and cave entrances/exits, evolve together, and that the caves at progressively higher elevations also have older periods of formation. The oldest breccias and sedimentary deposits are on the upper part of the network, whereas the youngest ones are often close to the modern alluvial plain. These processes of formation are in many respects very similar to those of the fluvial terraces formed during the drop of the alluvial plain, showing a stair-like morphology. Additionally, the alternation of infilling and erosion is strongly linked to the progressive downcutting of the alluvial plain that leads to a major change in both, water circulation and sedimentary deposits. The bone-bearing breccias, formed by typical sedimentary processes, yield vertebrate assemblages, often essentially composed of isolated teeth from middle- to large-sized mammals (Artiodactyla, Perissodactyla, Proboscidea, Carnivora, Rodentia, Primates). In terms of zoogeography, the continental Southeast Asian mammals belong to the Indochinese Subregion. After a brief review of the evolution of the faunas throughout the Pleistocene, we present a biochronological framework of the transition between the Middle Pleistocene and the Late Pleistocene, on the basis of our research in the karsts of Vietnam (Duoi U’Oi and Ma U’Oi sites) and Laos (Tam Hang site).     

猿人洞的溶洞演化和堆积旋回与北京猿人生活环境

猿人洞的溶洞演化过程按岩溶洞穴发生发展规律可划分为６个阶段．在洞穴发育的填充过程中,依据堆积物的成因类型,猿人洞中的中更新世洞穴堆积层可分为７个堆积旋回．每个堆积旋回可与年代相当的黄土堆积旋回和深海气候旋回—一对应．堆积旋回所显示的气候和洞穴环境变化均与北京猿人生活环境及其旧石器文化的发展有着密切的关系．     

Alternating aeolian,sabkha and shallow-lake deposits from the Middle Triassic Gipsdalen Formation,Scoresby Land,East Greenland

Gypsum-bearing deposits of the Gipsdalen Formation (Anisian ? Ladinian ?) are described and interpreted on the basis of lithology, sedimentary structures and sequential pattern.The basal Kolledalen Member consists in the northwestern part of the area of coarse-grained alluvial-fan deposits overlain by cross-bedded aeolian sandstones and finer-grained sabkha or shallow desert-lake deposits. The overlying Kap Seaforth Member displays wel;-developed cyclic sedimentation. In the southeastern part of the area the ideal cycle consists of, from bottom to top: cross-bedded aeolian sandstone, structureless or wave-rippled sandstone of sabkha flat—marginal desert-lake origin, thin wave-rippled sandstone and irregularly bedded mudstone of marginal desert-lake origin and horizontally laminated mudstone deposited in an expanded desert lake.Foreset dips of the cross-bedded aeolian sandstones suggest alternating periods of north-northeast and south-southeast palaeowinds. It is concluded that the aeolian deposits of the Gipsdalen Formation were deposited at low palaeolatitudes in the northern hemisphere. In the Middle Triassic summer seasons the Intertropical Convergence Zone probably lay north of the Jameson Land Basin, which was reached by south-southeast trade winds. During the rest of the year the zone was situated to the south and the area came under the influence of north-northeast trade winds.     

盘县大洞古人类遗址的地层和古气候研究

贵州盘县大洞的堆积物,自上而下可以分为3层。大洞主体堆积物为角砾堆积,来源于洞顶灰岩的崩塌,另外有人类遗物以及洞外片流作用带入的泥砂。人类化石、旧石器和哺乳动物化石主要分布在第2层角砾堆积中。堆积物在洞厅各部位均有相应分布,属同一沉积序列。已知的早期人类活动时间大约从260ka．B．P．开始,到142ka．B．P．前后结束,对应于深海氧同位素的第6、7阶段。角砾层下段,发育一套遭强烈溶蚀和风化的堆积物,地球化学分析结果显示其湿热的沉积环境,时间大约在260—180ka B．P．期间,对应于深海氧同位素第7阶段;大洞堆积物在气候变化周期上与黄土、青藏高原冰期序列可以对比。     

Seasonal regulation of the growth hormone-insulin-like growth factor-I axis in the American black bear (Ursus americanus)

The American black bear maintains lean body mass for months without food during winter denning. We asked whether changes in the growth hormone/insulin-like growth factor-I (GH-IGF-I) axis may contribute to this remarkable adaptation to starvation. Serum IGF-I levels were measured by radioimmunoassay, and IGF-binding proteins (IGFBPs) were analyzed by ligand blotting. Initial studies in bears living in the wild showed that IGF-I levels are highest in summer and lowest in early winter denning. Detailed studies in captive bears showed that IGF-I levels decline in autumn when bears are hyperphagic, continue to decline in early denning, and later rise above predenning levels despite continued starvation in the den. IGFBP-2 increased and IGFBP-3 decreased in early denning, and these changes were also reversed in later denning. Treatment with GH (0.1 mg·kg(-1)·day(-1) × 6 days) during early denning increased serum levels of IGF-I and IGFBP-3 and lowered levels of IGFBP-2, indicating that denning bears remain responsive to GH. GH treatment lowered blood urea nitrogen levels, reflecting effects on protein metabolism. GH also accelerated weight loss and markedly increased serum levels of free fatty acids and β-hydroxybutyrate, resulting in a ketoacidosis (bicarbonate decreased to 15 meq/l), which was reversed when GH was withdrawn. These results demonstrate seasonal regulation of GH/IGF-I axis activity in black bears. Diminished GH activity may promote fat storage in autumn in preparation for denning and prevent excessive mobilization and premature exhaustion of fat stores in early denning, whereas restoration of GH/IGF activity in later denning may prepare the bear for normal activity outside the den.     

New hominid fossils from the Swartkrans formation (1979-1986 excavations): craniodental specimens

Seventy-two individually numbered hominid craniodental fossils from recent excavations at Swartkrans are described. All derive from in situ decalcified breccia and/or unconsolidated sediments. A total of 20 specimens, representing 13 to 16 individuals derive from Member 1 "Lower Bank," two teeth derive from sediments along the Member 1-2 Interface, 38 fossils representing 19 to 24 individuals come from Member 2, and 12 teeth representing 9 to 11 individuals derive from Member 3. All but four of the specimens are attributable at the generic level; one specimen from Member 1 "Lower Bank" and five specimens from Member 2 are attributed to Homo, while the others represent Paranthropus. The proportional representation of Homo in the Swartkrans Formation is markedly higher in Member 2 (c. 33%) than in the Member 1 "Lower Bank" (c. 8%) and Member 1 "Hanging Remnant" (c. 5%) samples.     

Conservation implications of prey responses to wild dogs Lycaon pictus during the denning season on wildlife ranches

The spread of game ranching in southern Africa provides opportunities for the reestablishment of populations of endangered wild dogs extirpated by livestock ranchers. However, this potential has not been realized, partly because of negative rancher perceptions. Some ranchers believe that wild dogs impart costs by killing wildlife that could be utilized consumptively. Others complain that wild dogs make ungulates 'skittish' and cause local reductions in prey densities while denning. We compared the skittishness and density of prey species inside and outside the denning home ranges of nine wild dog packs in Zimbabwe. Wild dogs had no impact on prey skittishness, but prey species did occur at lower densities inside denning home ranges. In some scenarios, and particularly on fenced game ranches, wild dogs could cause prey population declines during denning. On small game ranches, the use of fences as a tool by wild dogs during hunting can increase the proportion of large prey species in their diet by up to 11 times, and thus increase the minimum area required to support that diet. In addition, game fencing is typically permeable to wild dogs but not their prey, preventing the recovery of prey populations through the natural influx of prey animals into the denning area following departure of the dogs. Wild dogs could thus impose significant financial costs to game ranchers hosting denning packs. Our findings emphasize the importance of promoting the formation of conservancies, where neighbouring landowners remove boundary fences to create larger contiguous wildlife areas.     

Re-appraisal of the stratigraphy and determination of new U-Pb dates for the Sterkfontein hominin site, South Africa

Sterkfontein Caves is the single richest early hominin site in the world with deposits yielding one or more species of Australopithecus and possible early Homo, as well as an extensive faunal collection. The inability to date the southern African cave sites accurately or precisely has hindered attempts to integrate the hominin fossil evidence into pan-African scenarios about human evolutionary history, and especially hominin biogeography. We have used U-Pb and U-Th techniques to date sheets of calcium carbonate flowstone inter-bedded between the fossiliferous sediments. For the first time, absolute age ranges can be assigned to the fossil-bearing deposits: Member 2 is between 2.8 ± 0.28 and 2.6 ± 0.30 Ma and Member 4 between 2.65 ± 0.30 and 2.01 ± 0.05 Ma. The age of 2.01 ± 0.05 Ma for the top of Member 4 constrains the last appearance of Australopithecus africanus to 2 Ma. In the Silberberg Grotto we have reproduced the U-Pb age of ∼2.2 Ma of for the flowstones associated with StW573. We believe that these deposits, including the fossil and the flowstones, accumulated rapidly around 2.2 Ma. The stratigraphy of the site is complex as sediments are exposed both in the underground chambers and at surface. We present a new interpretation of the stratigraphy based on surface mapping, boreholes logs and U-Pb ages. Every effort was made to retain the Member system, however, only Members 2 and 4 are recognized in the boreholes. We propose that the deposits formally known as Member 3 are in fact the distal equivalents of Member 4. The sediments of Members 2 and 4 consisted of cone-like deposits and probably never filled up the cave. The U-Th ages show that there are substantial deposits younger than 400 ka in the underground cave, underlying the older deposits, highlighting again that these cave fills are not simple layer-cakes.     

东谷坨遗址石制品原料利用浅析

本文从原料的岩性、来源与分布、原料的成因及开采方式等方面对东谷坨旧石器遗址石制品的原料进行研究 ,表明其岩性主要为燧石、微晶白云岩、硅质白云岩、硅质灰岩、构造角砾岩、石英岩以及中性火山岩等 ,与遗址附近基岩的出露和分布一致。区域范围内的地质调查和有关资料显示 ,石制品原料主要取自遗址周围出露的中元古界长城系高于庄组含燧石条带的微晶白云岩、太古界迁西群右所堡组石英岩以及侏罗系火山岩。燕山期和喜山期构造运动形成的断裂为原料的开采提供了便利条件。从构造破碎带附近直接拣取或从构造带上开采并打下石料是东谷坨遗址石器制造者获得原料的主要方式。对石制品原料的利用程度的统计和分析显示 ,东谷坨遗址在总体上对原料的利用程度是偏低的 ,多数标本还有进一步加工的余地。文中还讨论了原料对东谷坨石器工业的影响 ,对东谷坨一带旧石器遗址群石制品原料的综合分析提出了建设性设想     

U-series dating and taphonomy of Quaternary vertebrates from Brazilian caves

The geochronology and taphonomy of internationally important fossil bearing cave deposits were studied, both in the semi-arid Northern Bahia area and the subtropical southeastern Lagoa Santa area of Brazil. Taphonomic analysis suggests that the processes responsible for bone accumulation in the Brazilian caves vary between sites, and taphonomic bias can therefore be significant in causing differences in faunal composition. In the Toca da Boa Vista caves the presence of single articulated skeletons, and the entrance-related distribution indicate that random penetration of animals is the main mechanism of fossil accumulation, a process that biases the assemblage to smaller species, and takes place over extended time periods. In nearby Toca dos Ossos cave transport by runoff in the cave river is predominant, and biases the fauna remains to larger more robust bones and species. Deposition probably also occurred only at times of enhanced runoff giving a more contemporaneous assemblage. Similar processes were responsible for emplacement of the copious fossil remains in the more humid Lagoa Santa area, where terrigenous fossil deposits are found intercalated by massive speleothem calcite layers. In this area runoff under a drier climate probably accounts for the sediment emplacement inside caves. In both areas the mode of emplacement implies bias in the fossil record, resulting in fossil assemblages that do not mirror surface faunas, limiting palaeoenvironmental reconstruction.

Mass spectrometric U-series analysis of speleothem calcite overlaying fossil remains gives minimum ages for fossil deposition. These ages confirm the previous view that many of the deposits derive from the late glacial, but also show that much older material (some > 350,000 yr) is also present. The habitat requirements of critical fossil species such as bats and monkeys strongly suggest that they derive from much wetter periods when forest cover was present in the currently semi-arid Northern Bahia area. Taphonomy exerts a major control on the diversity and mode of emplacement of cave fossil deposits in eastern Brazil and thus detailed sedimentological and hydrological studies coupled with a sound geochronological approach are essential in quantifying the relative importance of each taphonomic processes before faunal and palaeoecological interpretations can be attempted.     

Studies OB the Microfossils from the Hebiancun Formation,Hutuo Group,Wutai Mountain Area,North China

Well preserved microfossils were here described from the middle of Hebiancun Formation, Hutuo Group, northern China, estimated to be 2,000 2,400 Ma years old based on the K-Ar and U-Pb isotopic. They were coccoids (Globophycuswenshanensis Xu sp. nov.) and filamentous (Siphonophycus cf. kestron and Siphonophycus sp.) and occur in petrographic thin sections. The coccoids were preserved by permineralization in the chert part of the conical stromatolites (Zhongtiaoshanella) and the filamentous in black chert. The paleoenviromental modal for the setting of the Hebiancun Formation was able to be reconstructed according to the microfossit assemblage and different lithology observed. The formation was divided in ascending orders as follows: The breccia; the thick sandy dolomite; the black chert in which the filamentous microfossils in subparalled colonies were preserved; and the dolomite with conical stromatolites in which the coccoidal microfossils with hyaline and unlamelleted sheath was observed. As mentioned above, it was conjectured that the descent and uplift of the geosynclinal area led to transgression and regression during the Hebiancun time. Compared with the all microfloras in the world known uptodate the characteristics of the microfossils from Hebiancun Formation was similar to that from Transvaal Supergroup, South Africa. Both of them show of the big sizeof the algal bodies inspite of different types. The algae Seemed to have a big cell period during their systematization.     

Paleoecological patterns at the Hadar hominin site, Afar Regional State, Ethiopia

Reconstructing paleoecological patterns associated with hominin taxa, such as Australopithecus afarensis, is important for understanding possible evolutionary mechanisms involved in extinction and speciation events. It is critical to identify local, regional, or pan-African causal factors because patterns at these different levels may affect separate populations of the same species of hominin in unique ways. Habitat reconstructions of 12 submembers of the Hadar and Busidima formations (approximately 3.8-2.35 Ma) are presented here along with faunal differences in these submembers through time. Habitats with medium density tree and bush cover dominated the landscape through much of the earlier time period in the Hadar Formation. The lowermost Sidi Hakoma Member is the most closed habitat. The Denen Dora Member shows the influence of frequent floodplain edaphic grasslands with high abundances of reducin bovids. There is an influx of ungulates in the Kada Hadar Member (approximately 3.2--approximately 2.96 Ma) that indicates a more arid habitat populated by mammals that were recovered from earlier deposits further south in Ethiopia and Kenya. In the younger deposits from the Busidima Formation at Hadar, the landscape was open wooded grassland with some floodplain environments. The fossil assemblages from the Busidima Formation show a substantial species turnover. Although high numbers of A. afarensis specimens are associated with the lower Sidi Hakoma Member, they clearly inhabited a variety of habitats throughout the entire Hadar Formation. Australopithecus afarensis from Laetoli through Hadar times appears to have been a eurytopic species.     

The Middle Pleistocene Al Mahrúqah Formation in the Murzuq Basin,northern Sahara,Libya evidence for orbitally-forced humid episodes during the last 500,000 years

Geological and geomorphological work in the endorheic Murzuq Basin (Fezzan) in the northern Sahara Desert, SW Libya, has revealed that the Middle Pleistocene Al Mahrúqah Formation consists of at least four limestone beds at four distinct elevations. The corresponding limestone beds are named (from oldest to youngest) the Antalkhatá Member, the Brak Member, the Bi'r az Zallaf Member, and the Aqar Member. The four members are interpreted as lacustrine deposits, and they are well distinguished by their spatial extent and lithology. Twenty-five radiometric and thermal ionisation mass spectrometric (TIMS) ²³⁰Th/U ages ranging from about 490–130 ka have been determined on these lacustrine limestones. According to these radiometric ²³⁰Th/U ages, the accumulation of the four limestone members of the Al Mahrúqah Formation followed the orbitally-forced (Milankovitch) eccentricity cycle of 100 ka during at least the last 400 ka. The four members formed in humid episodes of several tens of thousands of years' duration, when large lakes might have existed. The δ¹³C and δ¹⁸O values from samples of the four members of the Al Mahrúqah Formation provide independent genetic evidence on the lacustrine origin of the deposits in the Murzuq Basin. The spatial extent of the limestone deposits, and thus the intensity of the humid episodes, decreases at least from the Brak Member to the Aqar Member from about 52,000 km² to 1400 km², respectively. In spite of the limited precision and reliability of the new ²³⁰Th/U ages, it seems possible that short humid episodes interrupted the intervening arid episodes. Other long-term palaeohydrological records from northern and southern Africa as well as the Mediterranean region support the palaeoclimatic results from the Murzuq Basin.     

禄丰古猿化石地点地层概述

本文较详尽地记述了云南禄丰古猿化石地点附近的地质、地貌、地层情况以及产出古猿及大量脊椎动物化石的剖面。