Fossil Tooth Enamel Research Articles

Old Fossils, New Information: Insights into Site Formation Processes of Two Pleistocene Cave Sequences in Zambia from Enamel Amino Acid Geochronology

Intra-crystalline protein degradation (IcPD) analysis was undertaken on 80 fossil tooth enamel samples from four taxonomic groups (rhinocerotid, suid, equid, bovid) excavated from two archaeological cave sites in Zambia (Twin Rivers and Mumbwa Caves). Seventy-two (90%) of these fossils showed evidence of closed-system behaviour. The fossils’ relative extent of protein degradation between the sites was consistent with their known ages, with samples from Twin Rivers (Mid-Pleistocene) showing higher levels of degradation than Mumbwa Caves (late Mid-Pleistocene to late Holocene). At Twin Rivers, a potential trend between IcPD and excavation depth was observed, concordant with the working hypothesis of periodic deposition of sediments as slurry flows into a phreatic passage. However, greater depositional and taphonomic complexity was indicated by relatively wide ranges of IcPD values within individual excavation levels. These results are interpreted partly as the consequence of the excavation methods used, alongside reworking within the deposits, which had not previously been recognised. Whilst lack of stratigraphic control limited the investigation of taxonomic effect, one notable difference in the protein breakdown pattern of peptide chain hydrolysis was observed between rhinocerotid in comparison to the other studied taxa. We therefore recommend taxon-specific enamel amino acid geochronologies (AAGs) are developed in future. Whilst lack of comparator datasets meant it was not possible to create a calibrated, enamel AAG for the South-Central African region from these sites, Twin Rivers provides a case study illustrating the complexity of cave formation processes and the importance of direct dating for interpreting archaeological and palaeontological sequences.

Single-grain luminescence and combined U-series/ESR dating of the early Upper Palaeolithic Lagar Velho Rock Shelter, Leiria, Portugal

The existing radiocarbon (14C) dating framework for Lagar Velho is broadly consistent but provides limited constraint on several geoarchaeological complexes (GCs) and does not favour detailed chronological comparisons across all sectors of the site; including the stratigraphically disconnected child burial complex in the east area and the broader archaeological sequence in the central-west area. In this study, we undertake a complementary chronological assessment of Lagar Velho Rock Shelter using single-grain quartz OSL, single-grain quartz TT-OSL and combined U-series/ESR dating of fossil teeth, with the aim of establishing more comprehensive reconstructions of archaeological events and placing the human occupation sequence in a firmer regional climatic context. Expanding on the original chronological study, we also compare the published 14C datasets against widely used sample quality indicators (i.e., organic preservation and contamination proxies) to ensure reliable comparisons with our new luminescence and combined U-series/ESR ages. Eight 14C samples pass our combined chronological and stratigraphic hygiene criteria and are included in the final dating evaluations. Ten of the twelve optical dating samples produce homogeneous equivalent dose (De) datasets indicative of suitable daylight exposure. The replicate single-grain TT-OSL De datasets exhibit more pronounced scatter, consistent with enhanced potential for insufficient bleaching of TT-OSL residual doses in some karst settings. The fossil enamel samples dated using U-series/ESR span relatively low natural dose ranges, necessitating the inclusion of maximum dose (Dmax)-adjusted dose response curve fitting and additional background noise subtraction to avoid De biases of up to 13%. Stratigraphically consistent ages (n = 26) spanning the full archaeological infill sequence are obtained using the four different dating methods, providing a robust interpretive framework and underscoring the significant role of single-grain OSL and combined U-series/ESR dating for refining early Upper Palaeolithic histories of Iberia. Bayesian modelling of the combined chronological dataset reveals a site accumulation history spanning 35,750–23,440 cal. BP and provides improved age constraints on all GCs; particularly the al, bs, tc, gs and ls deposits that were previously undated or imprecisely constrained. The age of the child burial complex is refined to 29,410–28,280 cal. BP, potentially occurring within Greenland Interstadial 4. Comparison of the modelled GC ages from the east and west-central areas enables improved temporal correlations of depositional events across stratigraphically disconnected sectors of the site. This analysis suggests that the child burial complex and the Late Gravettian occupation are statistically indistinguishable based on current dating evidence. The new dating assessments reveal three periods of human occupation at Lagar Velho: the Late Gravettian (including the shorter duration child burial event) 31.6–26.0 ka from the end of Heinrich Stadial (HS) 3 until the emergence of HS2; the Terminal Gravettian 26.5–24.5 ka coinciding with HS2; and the Middle Solutrean 25.2–23.4 ka extending from HS2 to the end of Greenland Stadial 3. The timing of these occupations during late Marine Isotope Stage (MIS) 3 and early MIS 2 highlights the significance of central western Portugal for supporting regional human populations during periods when much of Europe was experiencing extreme cold, aridity and expanded glacial coverage.

ESR/U-series and pIR-IR290 dating of the Middle Pleistocene site of Lunel-Viel (LV I), Hérault, Southern France

The Mas des Caves site at Lunel-Viel, Southern France, is a complex of several caves, developed in Miocene limestone, that have yielded a rich archaeo-palaeontological sequence attributed to the Middle Pleistocene with abundant vertebrates and lithic artefacts. The first caves (LVI, II and III), discovered in 1800, were excavated at the beginning of the 19th century (Serres et al., 1828) before falling into oblivion for over a century. The main cavity is LVI, when LVII and III are smaller subparallel galleries not connected to LVI. In the early 1970s, research was conducted in the main gallery by E. Bonifay who discovered an extension named LVIV and the natural entrance (sinkhole, doline) both completely closed now.Recently, a multidisciplinary approach has been set up (DRAC-SRA Occitanie) to contextualize the ancient collections with the recent ones and to allow a better understanding of the site formation, palaeoenvironmental and behavioral history of the animals and humans who lived there (Brugal et al., 2021). The previous chronology based on faunal evidence yields important biomarkers (including new genus and species/subspecies) making Lunel-Viel a major Middle Pleistocene site in the European record. Among various dating techniques used in this study, trapped-charged methods such as combined ESR/U-series and pIR-IR290 were applied on fossil tooth enamel and on K-feldspars, respectively. The results obtained by both methods are in agreement and suggest a period of human occupation between 300 and 200 ka. This age range matches well with the composition of the faunal assemblage attributed to the second part of the Middle Pleistocene (biochronology) and which constrains the occupation to a cool/temperate and humid period which could be contemporaneous with the MIS7 (Lisiecki and Raymo, 2005) cited in figure 5 legend.

Comparative EPR Analysis of Modern and Fossil Tooth Enamel: Unveiling Aging-Induced Components

Comparative EPR Analysis of Modern and Fossil Tooth Enamel: Unveiling Aging-Induced Components

Stable isotope composition and concentration systematics of Ca and trace elements (Zn, Sr) in single aliquots of fossil bone and enamel

Measurements of modern bone and tooth enamel show that calcium stable isotopes (δ44Ca), zinc (δ66Zn), and strontium (δ88Sr) have great potential as ecological and dietary tracers for studies on fossil material. Despite the fact that these three elements can be recovered using sequential chromatographic extraction from a single aliquot, a multi-proxy study has not been attempted yet, which would allow a less destructive analysis of precious fossil material. The present study consists of analyzing δ44Ca, δ66Zn, δ88Sr, and 87Sr/86Sr values in fossil bone and tooth enamel of carnivore and herbivore mammals from the Camiac cave (Upper Pleistocene, Gironde, France). Our study aims at (1) developing a protocol for Ca, Zn, and Sr stable isotope analyses from a single fossil bone or enamel aliquot; (2) testing the respective preservation of biological isotopic signatures in bone and tooth enamel; and (3) comparing the patterning of the different isotopic systems in a fossil mammal community. In the present study, fossil enamel samples have not been leached, as it has been done so far for Zn isotope analyses, but fossil bone samples have been leached using diluted acetic acid or were left unleached. Using inclusive statistical analyses, we identify the effect of leaching on bone chemical compositions, and the concentration and isotope composition of Ca, Zn, and Sr in leached bone and unleached enamel show no sizeable diagenetic overprint. We report for the first time δ66Zn values in fossil bone. The results show that bone δ66Zn values mirror the pattern already observed in enamel, e.g., a significant trophic 66Zn depletion between herbivores and carnivores. Bone δ44Ca and δ88Sr values also mirror those in enamel, and the results highlight a clear distinction between ruminants and non-ruminants, the latter being 44Ca-enriched. The present study focuses on the importance of analyzing several isotopic systems in a single fossil bone or enamel aliquot and shows encouraging results for the preservation of biological isotopic signatures in fossil bone, despite the longstanding dread of a so-called associated pervasive diagenesis. The present study will therefore be useful to consider any precious fossil material with limited destructive sampling possibilities.

Reconstructing Pleistocene Australian herbivore megafauna diet using calcium and strontium isotopes.

Isotopes in fossil tooth enamel provide robust tools for reconstructing food webs, which have been understudied in Australian megafauna. To delineate the isotopic composition of primary consumers and understand dietary behaviour at the base of the food web, we investigate calcium (Ca) and strontium (Sr) isotope compositions of Pleistocene marsupial herbivores from Wellington Caves and Bingara (New South Wales, Australia). Sr isotopes suggest small home ranges across giant and smaller marsupial herbivores. Ca isotopes in Pleistocene marsupial herbivores cover the same range as those in modern wombats and placental herbivores. Early forming teeth are depleted in heavy Ca isotopes compared to late-forming teeth of a given individual, suggesting a weaning signal. Distinct Ca compositions between taxa can be interpreted as dietary niches. Some niches conform to previous dietary reconstructions of taxa, while others provide new insights into niche differentiation across Australian herbivores. Combined with the small roaming ranges suggested by Sr isotopes, the Ca isotope niche diversity suggests rich ecosystems, supporting a diversity of taxa with various diets in a small area.

Modeling periodicity in equid serial enamel isotopes as a proxy for precipitation seasonality

Seasonality shapes environments by driving vegetation patterns and faunal community composition, and identifying seasonality patterns in the past can provide unique insight into paleoenvironments and how they changed over time. Many environmental proxies operate on too large a time scale to glean data about intra-annual seasonality. However, serial enamel isotope samples from the teeth of high-crowned ungulates show promise for providing this temporal resolution of data. Interpreting these data remains a challenge due to the complexity of factors related to animal physiology and the isotopic values of environmental inputs. This study seeks to establish a method for interpreting intra-tooth isotopic change in modern equid teeth as a signal of seasonality by applying a linear mixed effect model to the isotope data to detect periodicity in serial enamel isotope values. Using a modern assemblage of zebra (Equus quagga) from Ol Pejeta Conservancy in Kenya, where long-term climate data has been collected, allows us to compare known climatic seasonality patterns to periodicity in the zebra tooth enamel isotopes. The results of the linear mixed effect modeling, in tandem with the climate data from Ol Pejeta, demonstrate the impact high precipitation variability can have on an environment. While our isotope results point towards measured precipitation seasonality patterns at Ol Pejeta, noise in our data and the variation identified by the models illustrate the challenges of working with serial enamel isotope data. Future refinement and application of this model will allow us to better characterize seasonality in both modern and fossil enamel datasets.

Pliocene hominins from East Turkana were associated with mesic environments in a semiarid basin

During the middle Pliocene (∼3.8–3.2 Ma), both Australopithecus afarensis and Kenyanthropus platyops are known from the Turkana Basin, but between 3.60 and 3.44 Ma, most hominin fossils are found on the west side of Lake Turkana. Here, we describe a new hominin locality (ET03-166/168, Area 129) from the east side of the lake, in the Lokochot Member of the Koobi Fora Formation (3.60–3.44 Ma). To reconstruct the paleoecology of the locality and its surroundings, we combine information from sedimentology, the relative abundance of associated mammalian fauna, phytoliths, and stable isotopes from plant wax biomarkers, pedogenic carbonates, and fossil tooth enamel. The combined evidence provides a detailed view of the local paleoenvironment occupied by these Pliocene hominins, where a biodiverse community of primates, including hominins, and other mammals inhabited humid, grassy woodlands in a fluvial floodplain setting. Between <3.596 and 3.44 Ma, increases in woody vegetation were, at times, associated with increases in arid-adapted grasses. This suggests that Pliocene vegetation included woody species that were resilient to periods of prolonged aridity, resembling vegetation structure in the Turkana Basin today, where arid-adapted woody plants are a significant component of the ecosystem. Pedogenic carbonates indicate more woody vegetation than other vegetation proxies, possibly due to differences in temporospatial scale and ecological biases in preservation that should be accounted for in future studies. These new hominin fossils and associated multiproxy paleoenvironmental indicators from a single locale through time suggest that early hominin species occupied a wide range of habitats, possibly including wetlands within semiarid landscapes. Local-scale paleoecological evidence from East Turkana supports regional evidence that middle Pliocene eastern Africa may have experienced large-scale, climate-driven periods of aridity. This information extends our understanding of hominin environments beyond the limits of simple wooded, grassy, or mosaic environmental descriptions.

Limits of calcium isotopes diagenesis in fossil bone and enamel

Diagenesis has been recognized for decades to significantly alter the trace elements biogenic signatures in fossil tooth enamel and bone that are routinely used for paleobiological and paleoenvironmental reconstructions. This signature is modified during diagenesis according to a complex continuum between two main processes, addition and substitution. For an additive-like, or early diagenesis, the trace elements biogenic profiles can be restored by leaching secondary minerals, but this technique is inefficient for a substitutive-like, or extensive diagenesis for which secondary trace elements are incorporated into the biogenic mineral. This scheme is however unclear for Ca, the major cation in tooth enamel and bone hydroxylapatite, whose stable isotope composition (δ44/42Ca) also conveys biological and environmental information. We present a suite of leaching experiments for monitoring δ44/42Ca values in artificial and natural fossil enamel and bone from different settings. The results show that enamel δ44/42Ca values are insensitive to an additive-like diagenesis that involves the formation of secondary Ca-carbonate mineral phases, while bone shows a consistent offset toward 44Ca-enriched values, that can be restored to the biogenic baseline by a leaching procedure. In the context of a substitutive-like diagenesis, bone exhibits constant δ44/42Ca values, insensitive to leaching, and shows a REE pattern symptomatic of extensive diagenesis. Such a REE pattern can be observed in fossil enamel for which δ44/42Ca values are still fluctuating and follow a trophic pattern. We conclude that Ca isotopes in fossil enamel are probably not prone to extensive diagenesis and argue that this immunity is due to the very low porosity of enamel that cannot accommodate enough secondary minerals to significantly modify the isotopic composition of the enamel Ca pool.

Structure and Chemical Composition of ca. 10-Million-Year-Old (Late Miocene of Western Amazon) and Present-Day Teeth of Related Species.

Molecular information has been gathered from fossilized dental enamel, the best-preserved tissue of vertebrates. However, the association of morphological features with the possible mineral and organic information of this tissue is still poorly understood in the context of the emerging area of paleoproteomics. This study aims to compare the morphological features and chemical composition of dental enamel of extinct and extant terrestrial vertebrates of Crocodylia: Purussaurus sp. (extinct) and Melanosuchus niger (extant), and Rodentia: Neoepiblema sp. (extinct) and Hydrochoerus hydrochaeris (extant). To obtain structural and chemical data, superficial and internal enamel were analyzed by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (SEM-EDS). Organic, mineral, and water content were obtained using polarizing microscopy and microradiography on ground sections of four teeth, resulting in a higher organic volume than previously expected (up to 49%). It is observed that both modern and fossil tooth enamel exhibit the same major constituents: 36.7% Ca, 17.2% P, and 41% O, characteristic of hydroxyapatite. Additionally, 27 other elements were measured from superficial enamel by inductively coupled mass spectrometry (ICP-MS). Zinc was the most abundant microelement detected, followed by Pb, Fe, Mg, and Al. Morphological features observed include enamel rods in the rodent teeth, while incremental lines and semiprismatic enamel were observed in the alligator species. The fossil enamel was in an excellent state for microscopic analyses. Results show that all major dental enamel’s physical, chemical, and morphological features are present both in extant and extinct fossil tooth enamel (>8.5 Ma) in both taxa.

Disentangling diagenetic and biogenic trace elements and Sr radiogenic isotopes in fossil dental enamel using laser ablation analysis

The reconstruction of life histories traits such as the ontogenic evolution of diet or sequences of mobility can be achieved for fossil mammals thanks to laser ablation analysis of trace elements concentration and radiogenic Sr isotope composition in dental enamel. However, a major limitation for the use of laser ablation to study fossil tooth enamel is that the analysis must be carried out on bulk sample hence prohibiting any ad hoc leaching step to remove diagenetic compounds. Biogenic and diagenetic trace elements along with the 87Sr/86Sr ratio must be monitored and post hoc correlation tests processed to isolate areas free of diagenesis. The present study combines a unique combination of biogenic (Sr and Ba), diagenetic (Mn and U) trace elements, major elements (Mg and Ca) and 87Sr/86Sr ratio time series obtained by means of laser ablation ICPMS and MC-ICPMS on a large number (n = 94) of fossil tooth enamel samples of humans and animals from a set of neighboring Neolithic sites in France. Bone fragments sampled from the same specimens are also analyzed for comparison. Trends between diagenetic and biogenic trace and major elements are first identified using inclusive data analysis. The trends are then validated at the scale of the laser ablation raster, and a protocol of data cleaning is developed to identify areas free of diagenesis. Non-significantly altered Sr/Ca, Ba/Ca and 87Sr/86Sr average values are thus gathered for each cleaned tooth enamel samples and are discussed, along with previously measured bone collagen δ13C and δ15N values, in terms of diet and mobility in the context of the Neolithic revolution.

Paleoenvironment of the late Miocene Shuitangba hominoids from Yunnan, Southwest China: Insights from stable isotopes

The Late Miocene witnessed significant changes in climate globally and was an important time in the evolution of hominoids. Here, we report the results of an isotopic study of Late Miocene mammalian teeth and freshwater shells from Shuitangba (Yunnan Province, China) – an important refugium for hominoids, and reconstruct paleoenvironmental conditions in the area. δ13C values of fossil enamel samples range from −15.5‰ to −1.0‰, with a mean of −11.3 ±2.3‰, and δ18O values vary from −14.2 to −4.6‰, averaging −9.7 ±2.2‰. Reconstructed diet-δ13C values for these fossil mammals indicate that although they fed mostly on C3 plants, many of them consumed some C4 vegetation. This suggests that the local ecosystem contained C4 grasses but was dominated by C3 plants. The intra-tooth δ18O variation of fossil herbivores is larger than what is found in modern herbivores. Reconstructed paleo-meteoric water δ18Ow values are on average lower than those inferred from modern samples and also lower than the average δ18Ow values of modern precipitation in the region. Similarly, δ18O values of fossil freshwater shells display a larger seasonal variation and are significantly lower than modern shells from Fuxian Lake in the same region. Thus, the δ18O data from both mammalian teeth and freshwater mollusk shells support a wetter climate, possibly with a stronger precipitation seasonality in the Late Miocene than today. Comparison of clumped isotope temperatures from fossil and modern shells suggests a mean annual temperature of ~15 to 16 °C in the Shuitangba area in the Late Miocene, which is ~3 to 4 °C higher than that of today. Taken together, our isotope results suggest that C4 grasses existed in local ecosystems in the area, likely in patches of grasslands or wooded grasslands in a mostly forested environment in the Late Miocene when the local and regional climate was warmer and wetter than today. Comparison of the δ13C records from Yunnan and the Siwalik region suggests that C4 biomass spread earlier in the Indian subcontinent on the southwest side of the Tibetan Plateau than in Yunnan on the southeast side of the Plateau. The transition from a relatively wet habitat to a more open and drier habitat is also more pronounced and begins earlier in the Siwalik region, relative to Yunnan. These regional differences in climate and ecosystem evolution may be linked to the unique growth history of the Himalayan-Tibetan Plateau.

The age of the Palaeolithic sedimentary layer of Hyangmokri cave site in the democratic People’s Republic of Korea

Hyangmokri cave site was newly excavated in Kangdong County, Pyongyang City a few years ago. The sedimentary deposits in the cave consist of seven different layers. According to the composition of sediments and features of archaeological finds, it is clear that Layers 4 and 5 are of the late Palaeolithic, Layer 6 is of the Neolithic and Layer 7 is of the Bronze Age. We determined dates of some samples from Layer 4 by using thermoluminscence (TL) and electron spin resonance (ESR) dating. We found out by using TL method that three calcite samples from Layer 4 date back to 34,780 ± 3,890, 31,490 ± 3,930 and 36,020 ± 4,160a respectively, while ESR ages of three bear fossil tooth enamel samples from Layer 4 are 35,680 ± 3,860, 31,910 ± 3,430 and 34,700 ± 3,760a respectively. There is good agreement between morphological research on archaeological finds and chronological research on several samples collected from Layer 4, the first sedimentary layer which contained lots of relics.

New application of strontium isotopes reveals evidence of limited migratory behaviour in Late Cretaceous hadrosaurs.

Dinosaur migration patterns are very difficult to determine, often relying solely on the geographical distribution of fossils. Unfortunately, it is generally not possible to determine if a fossil taxon's geographical distribution is the result of migration or simply a wide distribution. Whereas some attempts have been made to use isotopic systems to determine migratory patterns in dinosaurs, these methods have yet to achieve wider usage in the study of dinosaur ecology. Here, we have used strontium isotope ratios from fossil enamel to reconstruct the movements of an individual hadrosaur from Dinosaur Provincial Park in Alberta, Canada. Results from this study are consistent with a range or migratory pattern between Dinosaur Provincial Park and a contemporaneous locality in the South Saskatchewan River area, Alberta, Canada. This represents a minimum distance of approximately 80 km, which is consistent with migrations seen in modern elephants. These results suggest the continent-wide distribution of some hadrosaur species in the Late Cretaceous of North America is not the result of extremely long-range migratory behaviours.

New electron spin resonance (ESR) ages from Geißenklösterle Cave: A chronological study of the Middle and early Upper Paleolithic layers

Geißenklösterle Cave (Germany) is one of the most important Paleolithic sites in Europe, as it is characterized by human occupation during the Middle and early Upper Paleolithic. Aurignacian layers prior to 37–38 ka cal BP feature both musical and figurative art objects that are linked to the early arrival in Europe of Homo sapiens. Middle Paleolithic layers yielded lithic artifacts attributed to Homo neanderthalensis. Since human occupation at the site is attributed to both Neanderthals and modern humans, chronology is essential to clarify the issues of Neanderthal disappearance, modern human expansion in Europe, and the origin of the Aurignacian in Western Europe. Electron spin resonance (ESR) dating was performed on fossil tooth enamel collected from the Middle Paleolithic layers, which are beyond the radiocarbon dating range, and from the nearly sterile ‘transitional’ geological horizon (GH) 17 and the lower Aurignacian deposits, to cross-check ESR ages with previous radiocarbon, thermoluminescence and ESR age results. The Middle Paleolithic layers were dated between 94 ± 10 ka (GH 21) and 55 ± 6 ka (GH 18) by ESR on tooth enamel. Mean ages for GH 17, at 46 ± 3 ka, and for the lower Aurignacian layers, at 37 ± 3 ka, are in agreement with previous dating results, thus supporting the reliability of ESR chronology for the base of the sequence where dating comparisons are not possible. These results suggest that Neanderthals occupied the site from Marine Isotope Stage (MIS) 5 to the second half of MIS 3 and confirm the antiquity of early Aurignacian deposits. The presence of an almost sterile layer that separates Middle and Upper Paleolithic occupations could be related to the abandonment of the site by Neanderthals, possibly during Heinrich Stadial 5 (ca. 49–47 ka), thus before the arrival of H. sapiens in the area around 42 ka cal BP. These dates for the Middle Paleolithic of the Swabian Jura represent an important contribution to the prehistory of the region, where nearly all of the excavations were conducted decades ago and prior to the development of reliable radiometric dating beyond the range of radiocarbon.

Spectral Deconvolution of Fossil Tooth Enamel Electron Paramagnetic Resonance Spectrum

In this work the ESR method has been applied to determine the age of fossil tooth enamel found in Mingachevir archeological site (Azerbaijan, Mingachevir). The EPR spectrum of tooth enamel has been deconvoluted into four individual Gaussian lines. Equivalent dose (Absorbed dose in tooth enamel that was historically accumulated due to natural irradiation) calculated using dose-response curves of individual Gaussian lines shows significantly different values. Peak 1 (with g= 2.006848) gives a significantly lower, Peak 4 (with g=2.002942) a significantly higher value of absorbed dose. The use of integrated spectra gives lower absorption dose values than the use of differential spectra.

Calcium isotopes in enamel of modern and Plio-Pleistocene East African mammals

Calcium isotope analyses show a depletion of heavy calcium isotopes in vertebrates, compared to food sources along each trophic step. Recent studies show considerable variability of the calcium isotopic composition of bone and teeth in modern mammals, leading to inconclusive interpretations regarding the utility of Ca isotopes for trophic inference in mammal-dominated terrestrial ecosystems. Here, we analyzed modern enamel samples from the Tsavo National Park (Kenya), and fossil enamel samples dated from ca. 4 Ma to 1.6 Ma from the Turkana Basin (Kenya). We found a constancy of taxa ordering between the modern and fossil datasets, suggesting that the diagenesis of calcium isotopes is minimal in fossils. In modern herbivore samples using similar digestive physiologies, browsers are enriched in 44Ca compared to grazers. Both grazer and browser herbivore tooth enamel is enriched in 44Ca relative to carnivores by about +0.30‰. Used together, carbon and calcium isotope compositions may help refine the structure of the C3 and C4 trophic chains in the fossil record. Due to their high preservation potential, combining both carbon and calcium isotope systems represent a reliable approach to the reconstruction of the structure of past ecosystems.

Substrate control of C4 plant abundance in the Himalayan foreland: A study based on inter-basinal records from Plio-Pleistocene Siwalik Group sediments

Data from different parts of the globe including the Himalayan foreland suggest that the expansion of C4 plants was not synchronous and hence invoke influences of regional factors on C4 plants evolution. The disparity in the abundance of C4 plants across different regions of the Kangra sub-basin, NW Himalaya, has been attributed to variation in grain size of the substrate and its moisture content. In the absence of vegetation and climate data from the Upper Siwaliks of the Kangra sub-basin, the present study considers the adjacent Subathu sub-basin. The δ13C values of soil carbonate nodule (SC) from the Ghaggar and Moginanda regions and fossil tooth enamel from the Haripur Khol region of the Subathu sub-basin have been measured and compared to data from the other Siwalik regions to assess the spatio-temporal distribution of C4 plants. Additionally, the δ18OSC values have been evaluated to reconstruct local climatic conditions. Stable carbon and oxygen isotope data from SC across the Siwaliks indicate that climate was not the only driver influencing the C4 plant abundance.Comparison of the sedimentary architecture among the different Siwalik regions indicates that the abundance of overbank fine sediments is higher in the western Siwaliks than the central and eastern Siwaliks. The δ13C values and abundance of overbank fine sediments across different Siwaliks suggest a significant influence of substrate on the abundance of C4 plant in the Himalayan foreland.

On the potential of the Electron Spin Resonance (ESR) dating method in geoarchaeological contexts: an overview of 30 years of investigation in the Iberian Peninsula

ESR dating is a palaeodosimetric method based on the detection and quantification of the trapped charges accumulated over time in the crystal lattice of some materials due to their exposure to natural radioactivity. Like any chronometric dating methods, ESR has strengths and weaknesses. In particular, whilst the precision achieved with ESR is not as good as that of radiometric methods (e.g. radiocarbon, Ar-Ar or U-Th), it does have the advantage to being able to be used on a wide range of materials, covering thus almost any geological contexts during the last 2.6 Ma. Amongst them, the ESR dating of fossil tooth enamel and optically bleached sedimentary quartz grains are probably the most interesting applications in archaeology. This study mainly aims at showing an updated overview of the potential -and current limitations- of the ESR dating method used in geoarcheological contexts, through a synthesis of the previous studies carried out on various sites of the Iberian Peninsula that have been published over the last 30 years.

40Ar/39Ar and ESR/U-series data for the La Polledrara di Cecanibbio archaeological site (Lazio, Italy)

La Polledrara di Cecanibbio (20km from Rome) discovered in 1984, is a famous Middle Pleistocene site of the Italian peninsula (Lazio) mainly thanks to its excellent preservation state and its richness in archaeological and faunal remains. This deposit presents a typical Aurelian faunal assemblage with a large number of “elephants” specimens. A human tooth and scavenging traces on “elephants” bones were also pointed out. Palaeontological and archaeological remains are located in deposits characterized by its high percentage of white volcanic material blocks embedded in a fine matrix, laying on a fluvial volcano-sedimentary sequence. This archaeological sequence belongs to the Aurelia Formation, and was correlated to the MIS 10-9. To refine this age assignment we provided a multi-methods investigation including both 40Ar/39Ar and ESR/U-series methods. 40Ar/39Ar measurements made on single K-feldspars minerals extracted from white pumices within the archaeological horizon suggest a deposition age of 325±6ka while the ESR/U-series analyses applied on fossil enamel teeth highlighted a minimum age of 304±25ka, in agreement with the 40Ar/39Ar ages. These results allowed us to place with confidence the occupation as well as palaeontological assemblage of La Polledrara di Cecanibbio contemporaneously to the middle part of the MIS 9 period just after the interglacial optimum s.s. La Polledrara di Cecanibbio is hence now the most precisely and accurately dated Lower Palaeolithic site among the numerous sites from the Lazio province.