u series dating of fossil teeth and carbonates from snake cave thailand abstract snake cave thailand is an important site for the study of the evolution in southeast asia leading to a discovery of rich and various faunas including a human tooth fossils of large and small mammals converge to indicate on the basis of faunal assemblage a late middle pleistocene age for the fossiliferous layers on the other hand previous u series dating of carbonates furnished a lower limit for the fossils of about 130 ky in order to achieve a better comprehension of the chronology of the cave the uranium series method for absolute age determination has been applied to some carbonates older than those studied previously and to fossils themselves we used the isochron technique approach to yield valuable ages because spleleothem samples consist in a mixture of calcite and detrital contamination the results obtained suggest that the main fossiliferous level is older than about 160 ky the application of the u series method to tooth samples from this tropical cave leads to erroneous ages probably because of post depositional groundwater movements

late pleistocene mammalian assemblages of southeast asia new dating mortality profiles and evolution of the predator prey relationships in an environmental context karstic sites have great potential for yielding data regarding changes in faunal communities in the pleistocene of southeast asia in this region the majority of fossil bearing deposits are karstic breccias which generally demonstrate a complicated sedimentary history while most of the mammalian assemblages recovered in these deposits are only composed of isolated teeth their study remains essential for reconstructing paleoecology and paleoclimatology of the region we analyzed the assemblages recovered in three mainland and two insular karstic sites tam hang south and nam lot in northern laos duoi u oi in northern vietnam punung in central java and sibrambang in western sumatra and obtained new chronologies for three of these sites so that their significance could be discussed within their correct chronological context the resulting age ranges place the sites in mis5 and mis4 the comparative analysis of the faunas in terms of taphonomy taxonomic diversity and abundance and mortality profiles cervus unicolor sus scrofa sus vittatus rhinocerotids and tapirus indicus reveals marked differences in prey predators carnivores and or humans relationships in relation to habitat the study of hominines bearing sites punung nam lot duoi u oi allows us to emphasize different interactions with large carnivores felids hyaenids canids

model for the origin of the troodos massif cyprus and other mideast ophiolites any comprehensive model for the origin of the troodos complex and other mideast ophiolite complexes must explain the geochemical evidence for subduction zone involvement the thin inferred oceanic crust the extensional environment indicated by sheeted dikes the existence of fault zones perpendicular to the inferred spreading axes and the discontinuous nature of ophiolite exposures around the arabian block the andaman sea region of the indian ocean may provide an actualistic model for the origin of these ophiolites there spreading takes place in short segments above a subduction zone in the region of active spreading the andaman sea model substantially accounts for the known geologic and geophysical data from the circum arabian ophiolite belt and it leads to some predictions about the structural and geophysical relationships to be expected in this important belt the model also predicts that andaman sea spreading center magmas may be similar in composition to those found in the mideast ophiolites

spreading structure of the troodos ophiolite cyprus orientations of dikes within the sheeted dike complex of the troodos ophiolite reveal primary spreading structure produced at a complex ridge transform intersection three structural grabens are defined by listric and planar normal faults and rotated dikes that dip symmetrically toward graben axes faults flatten at depth into a detachment within the upper parts of the plutonic complex large exhalative massive sulfide deposits occur within the pillow sections of two of the grabens and appear to be associated with underlying altered and mineralized normal fault zones that channeled hydrothermal fluids we suggest that the grabens are fossil axial valleys produced by successive eastward jumps of an approximately north trending present coordinates slow spreading ridge crest a simple model for ridge migration indicates eastward jumps of 8 13 km changes in ridge orientation are suggested by changes in trends of dikes and graben axes comparison of the pattern of dikes near the arakapas fault zone with the structure of active ridge transform intersections suggests that the fault is a right offset sinistral transform in contrast to earlier models in which a ridge to the west of the exposed troodos complex was proposed

mid ocean ridges fine scale tectonic volcanic and hydrothermal processes within the plate boundary zone a first order model of spreading centers as idealized linear boundaries of crustal and lithospheric generation provides only a gross understanding of global scale plate kinematics as we attempt to understand the complexity of crustal and lithospheric structure of two thirds of the earth s surface it is becoming increasingly necessary to study the tectonic volcanic and hydro thermal processes within the spreading center plate boundary zone all ocean ic crust bears the imprint of these processes this review focuses on a few selected topics concernining the fine scale tectonics and geophysics of the active axial zone of mid ocean ridges with reference to associated volcanic and hydrothermal processes it draws heavily on recent studies that use deeply towed instrument packages multi beam bathymetric mapping ocean bottom instruments and alvin e g the famous amar rise and galapagos expeditions we begin with a review of the large scale structure of spreading centers we then take a close look at the axial neovolcanic zone and progress away from the axis through the active tectonic zones next we consider the characteristics of the axial magma chamber and associated hydrothermal actvity as well as the generation of magnetic anomaly stripes and their implications for crustal generation one of our findings is that the initial two dimensional model of volcanic and tectonic zones must be expanded upon to allow for variations

east pacific rise near 13 n geology of new hydrothermal fields abundant massive sulfide deposits are present at the crest of the east pacific rise near 13 north where the opening rate is about 12 centimeters per year large manganese and helium 3 anomalies in seawater samples evidence of intense present day activity of hydrothermal springs indicate that sulfides are still being produced along this segment of the rise massive sulfides also occur on adjacent off axis seamounts

oxygen isotope evidence for submarine hydrothermal alteration of the del puerto ophiolite california abstract the oxygen isotope compositions and metamorphic mineral assemblages of hydrothermally altered rocks from the del puerto ophiolite and overlying volcaniclastic sedimentary rocks at the base of the great valley sequence indicate that their alteration occurred in a submarine hydrothermal system whole rock 18o compositions decrease progressively down section with increasing metamorphic grade 22 4 smow to 13 8 for zeolite bearing volcaniclastic sedimentary rocks overlying the ophiolite 19 6 to 11 6 for pumpellyite bearing metavolcanic rocks in the upper part of the ophiolite s volcanic member 12 3 to 8 1 for epidote bearing metavolcanic rocks in the lower part of the volcanic member 8 5 to 5 7 for greenschist facies rocks from the ophiolite s plutonic member 7 6 to 5 8 for amphibolite facies or unmetamorphosed rocks from the plutonic member modelling of fluid rock interaction in the del puerto ophiolite indicates that the observed pattern of upward enrichment in whole rock 18o can be best explained by isotopic exchange with discharging18o shifted seawater at fluid rock mass ratios near 2 and temperatures below 500 c 18o depleted plutonic rocks necessarily produced during hydrothermal circulation were later removed as a result of tectonism submarine weathering and later burial metamorphism at the base of the great valley sequence cannot by itself have produced the zonation of hydrothermal minerals and the corresponding variations in oxygen isotope compositions the pervasive zeolite and prehnite pumpellyite facies mineral assemblages found in the del puerto ophiolite may reflect its origin near an island arc rather than deep ocean spreading center

oxygen and carbon isotope evidence for seawater hydrothermal alteration of the macquarie island ophiolite abstract rocks of the miocene macquarie island ophiolite south of new zealand have oxygen and carbon isotopic compositions comparable to those of seafloor rocks basalt glass and weathered basalts have 18o values at 5 8 6 0 and 7 9 9 5 respectively similar to drilled seafloor rocks including samples from the leg 29 dsdp holes near macquarie island compared to the basalt glass the greenschist to amphibolite facies metaintrusives are depleted in18o 18o 3 2 5 9 similar to dredged seafloor samples whereas the metabasalts are enriched 18o 7 1 9 7 although the gabbros are only slightly altered in thin section they have exchanged oxygen with a hydrothermal fluid to a depth of at least 4 5 km there is an approximate balance between18o depletion and enrichment in the exposed ophiolite section the carbon isotopic composition of calcite in the weathered basalts 13c 1 0 2 0 is similar to those of drilled basalts but the metamorphosed rocks have low 13c values 14 6 to 0 9 these data are compatible with two seawater circulation regimes in the upper regime basalts were weathered by cold seawater in a circulation system with high water rock ratios 1 0 based on calcite compositions weathering temperatures were less than 20 c and the carbon was derived from a predominantly inorganic marine source as previously suggested for the samail ophiolite it is postulated that the lower hydrothermal regime consisted of two coupled parts at the deeper levels seawater circulating at low water rock ratios 0 2 0 3 and high temperatures 300 600 c gave rise to18o depleted gabbro and sheeted dikes via open system exchange reactions during reaction the seawater underwent a shift in oxygen isotopic composition 18o 1 0 5 0 and subsequently caused18o enrichment of the overlying metabasalts in the shallower part of the hydrothermal regime the metabasalts were altered at relatively high water rock ratios 1 0 10 0 and temperatures in the range 200 300 c the relatively low water rock ratios in the hydrothermal regime are supported by the low 13c values of calcite interpreted as evidence of juvenile carbon in contrast to the inorganic marine carbon found in the weathered basalts

seawater basalt reaction and the origin of greenstones and related ore deposits massive sulfide deposits of copper zinc and iron and associated stringer deposits multicomponent equilibrium calculations of the reaction of seawater with tholeiitic basalt at 300 degrees c followed by calculation of the effects of cooling the resultant solution to 25 degrees c and mixing it with seawater the calculated mineralogy and zoning patterns resemble many natural ore assemblages observed in deposits of the kuroko type east pacific rise west shasta district according to the calculations silica should be abundant in the massive sulfide deposits modified journal abstract

diagenesis in prehistoric caves the use of minerals that form in situ to assess the completeness of the archaeological record an interpretation of the archaeological record in particular that of a prehistoric cave site is complicated by the diversity of depositional and post depositional processes that affect the material deposited here we propose to use the authigenic minerals that form in situ within the cave sediments to reconstruct the ancient chemical environments in the sediments this can be done by experimentally determining the conditions under which each of the authigenic minerals are stable although this information is not available to date for minerals formed in a prehistoric cave we present calculated stability field data for the relevant minerals the results clearly demonstrate the feasibility of this approach this information particularly if based on measurements of real authigenic cave minerals will facilitate an assessment of the completeness of the cave archaeological record this is particularly important for determining whether or not the distributions of archaeologically important materials such as bones teeth plant phytoliths charcoal and ash reflect their original burial distributions or were altered as a result of secondary diagenetic processes

esr dating of the last interglacial mousterian at karain cave southern turkey abstract we have obtained esr ages on 18 teeth from archaeological levels ah16 ah27 exposed at the east profile in compartment e at karain cave this sequence exhibits a transition in lithic assemblage from a classic charentian to a karain zagros type mousterian between levels ah27 and ah25 and two calcite cemented soils at levels ah22 and ah16 which have been interpreted as climatic warm phases since we found no systematic increase in tooth ages with depth we assigned this sequence a mean early uptake eu age of 108 23 ka and mean linear uptake lu age of 121 27 ka on the basis of 37 subsamples from 16 teeth in this site the precision of individual tooth ages suffered little from the problems associated with uranium uptake however this advantage was offset due to uncertainties arising from the rather inhomogeneous nature of the enclosing strata which contained various sizes of limestone blocks with intervening sediment this led to difficulties in ascribing a precise annual gamma radiation dose to individual teeth in such a lumpy gamma radiation field considerable scattering of the individual tooth ages occurred mainly because the annual gamma dose comprised greater than 50 of the total annual dose to the individual teeth on the basis of the esr dating results we infer that deposition of the two different lithic assemblages and both the penultimate and the final climatic warm phases at karain probably occurred during oxygen isotope stage 5 we also conclude that these lithic assemblages are significantly different than contemporaneous levantine mousterian industries which occur about 700 km to the southeast

the interrelationship between magmatic and ore forming hydrothermal processes in the oman ophiolite the semail ophiolite of oman contains numerous gossans minor sulfide showings and ferromanganoan deposits as well as several massive sulfide deposits the largest of which 8 x 10 6 metric tons is the deposit of lasail detailed field mapping of the lavas and shallow intrusions around this deposit in conjunction with petrographic studies of their metamorphic assemblages enables the ore forming hydrothermal activity to be related to the location and evolution of an underlying magma chamber it can be demonstrated that the deposit formed in the short time interval between the eruption of a lava unit the geotimes unit at a marginal ocean basin spreading axis and the eruption of a second lava unit the lasail unit at an off axis or arc seamount moreover it was the seamount not the spreading axis magma chamber which drove the ore forming hydrothermal convection providing both a near surface heat source and by virtue of its intrusive pressure a localized fracture system on its flanks subsequent eruptions from this same magma chamber then provided a protective capping for the deposit the orientations and distributions of andesitic cone sheets show that the magma chamber lay some 1 5 km from the deposit itself and was in fact a magma cupola developed on the flanks of a much larger magma chamber similar though less detailed studies of other deposits in oman indicate that only very small mound deposits lie within the spreading axis lavas themselves the majority of deposits lie at the boundary between the spreading axis and seamount lavas and another group of deposits is related to the magma chambers that fed a third submarine lava unit the alley unit also associated with the construction of the seamounts these results may provide useful constraints for future mineral exploration programs in the oman and perhaps also in other ophiolite complexes and on the ocean floor

geochronology of ailuropoda stegodon fauna and gigantopithecus in guangxi province southern china abstract pleistocene faunas from south china are difficult to subdivide based on the long temporal ranges of many taxa and a reduced number of genera in comparison to faunas from temperate north china in south china the ailuropoda stegodon fauna is a very general one and includes a relatively stable suite of genera that apparently persisted for long periods of time these attributes have made constraining its time range difficult application of electron spin resonance esr dating of tooth enamel constrains the ages well where uranium uptake was minor where uranium uptake into teeth was significant an approach combining esr and 230th 234u isotopic analysis also yields excellent ages previous estimates of early middle and late pleistocene time ranges previously determined by biostratigraphic seriation for the ailuropoda stegodon fauna are confirmed in all cases but are made more precise with our approach including specific time ranges for certain archaic taxa absolute dating also yields an extended time range for gigantopithecus blacki of 1200 to 310 ka

the cave of the monk ban fa suai chiang dao wildlife sanctuary northern thailand biostratigraphic and paleoecological analyses of southeast asian pleistocene faunal sites are based on the assumption that paleontological assemblages are homogeneous this means that the sites formed during a time range shorter than biological evolution range and above all without faunal replacement induced by environmental successions detailed study of the cave of the monk paleontological site in thailand has lead to the conclusion that the complex pattern of this southeast asian paleontological site cannot support such an assumption the cave of the monk provides an ailuropoda stegodon assemblage typical of southeast asia pleistocene fauna the pluridisciplinary study presented here includes i site morphology description ii sedimentological analysis of fossiliferous deposits iii taphonomy study of the bone assemblage and iv electron spin resonance esr dating of tooth samples this integrated approach demonstrates the existence of a pleistocene porcupine den inhabited during mis 3 and 2 the features of this site are commonly reported for other paleontological sites of the area indicating that this kind of site formation is a very general one in southeast asia esr dating and porcupine ethological reports are used to question the site time averaging a time range of a few tens of thousands of years is suggested the paleoecological value of the site can then be discussed on one hand the assemblage is thought to be a valuable paleoenvironmental record considering that the bone accumulation agent is reputed to represent the fauna present in the environment without bias on the other hand the time averaging of the site indicates that site formation range likely covered the environmental fluctuations of the last climatic cycle this last hypothesis is confirmed by the alternating association of species indicated by the stratigraphic distribution of the faunal remains the research demonstrates the need for integrated and pluridisciplinary taphonomic study of southeast asian paleontological sites it also reveals the utility of a microstratigraphic analysis of a fossiliferous karst deposit in order to disentangle the succession of pleistocene mammals in response to environmental changes

geometry conditions and timing of off axis hydrothermal metamorphism and ore deposition in the solea graben the recent discovery of fossil spreading axes along the northern margin of the troodos ophiolite1 provides a unique opportunity to compare a fossil seawater hydrothermal system with systems of modern oceanic spreading centres2 6 whereas previous accounts of ophiolite hydrothermal systems7 13 including troodos14 16have elucidated many aspects of sea floor hydrothermal metamorphism earlier workers have not placed ophiolite hydrothermal features within any specific spreading centre structural framework most ophiolites exhibit complex histories of post accretion deformation that mask or obliterate early structures related to seafloor spreading the troodos ophiolite is apparently still in the process of being emplaced 17 and most structural elements at troodos appear to have originated beneath a cretaceous sea floor1 we have discovered an extensive area of intense seawater hydrothermal alteration within the sheeted dyke complex of the solea graben fig 1 the metamorphic petrology and oxygen isotope geochemistry of 100 dyke samples from this graben reveal the size and three dimensional geometry of the hydrothermal system and yield estimates of temperature salinity oxygen isotope composition and recharge discharge geometry for fluids that transported the constituents of massive sulfide orebodies geometric discordance between the trends of the hydrothermally altered area and of earlier seafloor spreading structures compels us to consider a post spreading off axis origin for the orebodies of the solea graben

vertebrate preservation in fluvial channels abstract two taphonomic modes for attritional vertebrate assemblages in channels are proposed based on the sedimentary context of the vertebrate remains and taphonomic features of the bones themselves the channel lag mode includes bones that are buried with coarse lithologies near the bases of active channels the channel fill mode occurs in fine grained to mixed fills of abandoned channels the extreme for a channel lag assemblage would be a cluster of allochthonous abraded unidentifiable fragments and the extreme for a channel fill assemblage would be a cluster of autochthonous unbraded complete skeletons between these extremes there is a broad spectrum of possible taphonomic histories for bones in channels but distinct channel lag vs channel fill modes can be recognized in fluvial deposits in different tectonic and climatic settings throughout the phanerozoic physical and biological processes that affect the different modes produce different samples of vertebrate paleocommunities with bones in the channel lag mode representing transported remains from a variety of habitats whereas channel fill assemblages are more autochthonous and habitat specific channel facies channel pattern and alluvial architecture are used to develop hypotheses concerning how the taphonomic modes relate to different scales of fluvial processes fluvial systems with numerous abandoned channels provide more sites for preservation of relatively complete fossil vertebrates in channel fills while systems that continually rework sediments by lateral migration preserve more vertebrate remains as channel lags large scale physical controls on channel pattern and fluvial architecture probably have had significant effects on the quality and quantity of the vertebrate record throughout the history of land vertebrates taphonomic modes provide a basis for comparing faunas with similar preservational histories throughout the geologic record and they can help to minimize biases in important paleobiological parameters such as diversity estimates and the timing of appearance and extinction events

new palaeontological assemblage sedimentological and chronological data from the pleistocene ma u oi cave northern vietnam abstract this paper describes recent material gathered during the second fieldwork at ma u oi in november 2002 by a vietnamese french japanese team the ma u oi cave located in the province of hoa binh 60 km sw from hanoi northern vietnam belongs to a karstic network developed in triassic dark grey limestones the cave is filled with coarse grained breccias containing numerous fossil remains partially preserved at several loci inside the cave wall vault and ground we describe new teeth which confirm the occurrence of mammal taxa already mentioned at ma u oi bacon et al 2004 bacon a m demeter f schuster m long v t thuy n k antoine p o sen s nga h h huong n t m 2004 the pleistocene ma u oi cave northern vietnam palaeontology sedimentology and palaeoenvironments geobios 37 305 314 while others mainly microvertebrates emphasize the occurrence of new species for the pleistocene of vietnam we report here for the first time the occurrence of these microvertebrates of different groups primates rodents insectivores small reptiles and amphibians in the faunal assemblage among mammal taxa the presence of one more hominid affiliated to archaic homo is also attested by our findings u th dating carried out on 2 samples extracted from breccia speleothems confirms the biochronological estimate with fossiliferous fillings ranging from late middle pleistocene to late pleistocene

measuring the post depositional destruction of bone in archaeological assemblages abstract post depositional processes have affected most archaeozoological assemblages often causing fragmentation or destruction of bone which can vary by assemblage and hamper interpretations of the original element representation klein cruz uribe 1984 the analysis of animal bones from archaeological sites chicago university of chicago press prior to performing interassemblage comparisons analysts must first assess the post depositional destruction for each assemblage hammerstone breakage and hyaena ravaging experiments show that compact bones carpals tarsals fibulae are rarely fragmented therefore fragmentation of these bones in archaeozoological assemblages should be the result of post depositional destruction a completeness index for compact bones provides a description of the magnitude of post depositional destruction because the completeness index is independent of differential fragmentation and transport by bone collectors and quantification variation between researchers the efficacy of the completeness index for showing varing completeness of archaeological bone is demonstrated by comparing two late pleistocene archaeological sites in kenya when guided by experimental results the completeness index allows an evaluation of the impact of post depositional destruction on the two kenyan assemblages published archaeozoological reports must provide a measure of post depositional destruction or else the usefulness of the data for comparative analysis is compromised

active hydrothermal vents and sulfide deposits on the southern juan de fuca ridge massive sulfide deposits rich in zinc and silver were recovered from the juan de fuca ridge 500 km west of oregon in september 1981 the samples recovered are composed largely of zinc sulfide with lesser amounts of iron lead and copper sulfide most of the deposits occur at a series of hydrothermal vents within a relatively continuous depression in the center of a smooth 1 km wide valley along the ridge axis the depression appears to be formed by collapse of a lava lake possibly modified by extensional faulting the axial valley floor outside the depression is underlain by fresh glassy ferrobasalt sheet and lobate flows two types of sulfide mineral deposits were dredged from one of the hydrothermal vents 1 angular slabs of dark gray zinc sulfide and 2 subrounded fragments of porous light gray zinc sulfide the samples contain fresh sphalerite zoned wurtzite pyrite and minor amounts of marcasite galena and chalcopyrite cubanite the spreading rate of the juan de fuca ridge and the composition of the sulfide samples are generally similar to the east pacific rise lat 21 n site however the texture and geologic setting of the sulfide deposits are significantly different

testing the savannah corridor hypothesis during mis2 the boh dambang hyena site in southern cambodia abstract the boh dambang karstic site in southern cambodia kampot province is a mammal bone rich deposit in a hyena site very few hyena sites have been recovered in the pleistocene of southeast asia thus little information is known about the foraging abilities of hyenas during that period and their decline in the region while the other hypercarnivores tiger leopard and dhole persisted until present day to constrain the site we applied luminescence red tl and single grain osl esr and u th dating methods to the sediments and faunal teeth respectively the resulting age estimates suggest that the site represents an accumulation of a young deposit with faunal teeth in the range of 25 18 ka that was last exposed to sunlight between 8 and 7 ka and an older deposit containing older teeth 100 80 ka that have been eroded from the upper caves in the system and incorporated into the younger deposit thus the faunal age of 25 18 ka mis2 provides the best estimate for the age of the hyena site during lgm 26 5 19 ka we analysed the assemblage of isolated teeth in terms of taxonomic diversity and abundance the role of bone accumulators either carnivores or rodents has been precised through a taphonomic analysis diet was reconstructed through measurement of 13 c values of tooth enamel the taphonomic analysis reveals that the hyenas were the main bone accumulators at boh dambang porcupines were aslo a factor in the accumulation of remains the results show that the spotted hyenas hunted large sized herbivores 600 kg in a mixed environment dominated by grassland these data along with evidence from other pleistocene faunas from southeast asian mainland in terms of prey preference of hyenas rhinoceroses versus large bovines also reveal marked differences in relation to habitat type possible causes of the decline of the spotted hyena in the indochinese sub region hypercarnivory high trophic level comparable foraging strategies with hunters gatherers and climatic changes are tentatively proposed at this point

a sustainable review of the middle pleistocene benchmark sites including the ailuropoda stegodon faunal complex the proboscidean point of view abstract the different ecologies times of extinction and last stand of both elephas and stegodon in south east asia cover almost two million years in the middle pleistocene both taxa belong to the complex ailuropoda stegodon this regional complex is considered to have a chronological significance and further palaeoecological palaeobiogeographical or biochronological studies use this assemblage as a benchmark nevertheless such studies do not provide sufficient information regarding site formation and duration to be consistent enough to do so at an appropriate resolution mis timescale focussing attention on the occurrence of proboscideans a critical review of the robustness of the geological taphonomical and chronological data of middle pleistocene faunal assemblages suggests the necessity to undertake a deep reappraisal of this biochronological benchmark recommendations were provided in the 1980s not to use mixtures of faunal assemblages and progress in geochronology for two decades is available nevertheless a review of proboscideans suggests the necessity of a severe revision leading to scepticism concerning the use of the ailuropoda stegodon complex as an ecological marker extended to other taxa this review casts serious doubts on former and current paleoecological modellings and studies

characteristics of pleistocene megafauna extinctions in southeast asia the extinction of large bodied taxa from the pleistocene in southeast asia is examined although the chronological resolution of these extinctions is poor and number of excavations in the region relatively few broad characteristics of these extinctions can be described many taxa which became extinct appear to have been endemic to regions within southeast asia while some taxa which experienced extinction or severe range reduction occurred in several regions members of the latter group include proboscideans stegodon and palaeloxodon the pygmy hippopotamus hexaprotodon the orangutan pongo hyenas crocuta and hyaena the giant panda ailuropoda tapirs tapirus and megatapirus rhinoceroses rhinoceros and the giant asian ape gigantopithecus the loss of these species cannot be assigned to a single cause rather their disappearance is likely tied to both climatic and human agents unlike other regions which experienced megafauna extinctions eustatic changes in sea level in southeast asia seems to have been an important factor

dated co occurrence of homo erectus and gigantopithecus from tham khuyen cave vietnam abstract tham khuyen cave lang son province northern vietnam is one of the more significant sites to yield fossil vertebrates in east asia during the mid 1960s excavation in a suite of deposits produced important hominoid dental remains of middle pleistocene age we undertake more rigorous analyses of these sediments to understand the fluvial dynamics of pleistocene cave infilling as they determine how skeletal elements accumulate within tham khuyen and other east asian sites uranium thorium series analysis of speleothems brackets the pleistocene chronology for breaching infilling and exhuming the regional paleokarst clast analysis indicates sedimentary constituents including hominoid teeth and cranial fragments accumulated from very short distances and under low fluvial energy electron spin resonance analysis of vertebrate tooth enamel and sediments shows that the main fossil bearing suite s1 s3 was deposited about 475 thousand years ago among the hominoid teeth excavated from s1 s3 some represent homo erectus and gigantopithecus blacki criteria are defined to differentiate these teeth from more numerous pongo pygmaeus elements the dated co occurrence of homo erectus and gigantopithecus blacki at tham khuyen helps to establish the long co existence of these two species throughout east asia during the early and middle pleistocene

open system modelling for u series and esr dating of teeth abstract the study of the constituents of teeth dentine and enamel by a combination of esr and u series techniques offer unique constraints on the history of uranium migration into these materials our results imply that it is inappropriate to assume a simplified u uptake model for neither the components of a single tooth nor for the faunal remains of a given site however the combination of both methods may provide a new technique for establishing reliable chronologies for archaeological quaternary sites of up to several hundred thousand years