Search publications of the members of the Royal Belgian institute of natural Sciences
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Under pressure: the relationship between cranial shape and burrowing force in caecilians (Gymnophiona)
- Caecilians are elongate, limbless and annulated amphibians that, with the exception of one aquatic family, all have an at least partly fossorial lifestyle. It has been suggested that caecilian evolution resulted in sturdy and compact skulls with fused bones and tight sutures, as an adaptation to their head-first burrowing habits. However, although their cranial osteology is well described, relationships between form and function remain poorly understood. In the present study, we explored the relationship between cranial shape and in vivo burrowing forces. Using micro-computed tomography (µCT) data, we performed 3D geometric morphometrics to explore whether cranial and mandibular shapes reflected patterns that might be associated with maximal push forces. The results highlight important differences in maximal push forces, with the aquatic Typhlonectes producing a lower force for a given size compared with other species. Despite substantial differences in head morphology across species, no relationship between overall skull shape and push force could be detected. Although a strong phylogenetic signal may partly obscure the results, our conclusions confirm previous studies using biomechanical models and suggest that differences in the degree of fossoriality do not appear to be driving the evolution of head shape.
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WOODAN : an online database of archaeological wooden objects
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Novel insights into prehistoric land use at Stonehenge by combining electromagnetic and invasive methods with a semi-automated interpretation scheme
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Woodland Management as Major Energy Supply during the Early Industrialization: A Multiproxy Analysis in the Northwest European Lowlands
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Editorial
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Editorial
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Geochemistry of nummulites as proxy for Eocene climate change in the Southern North Sea Basin
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Geochemistry of nummulites as proxy for Eocene climate change in the Southern North Sea Basin.
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Geochemistry of Nummulites as a proxy for the Eocene paleotemperature evolution in the Southern North Sea Basin: an Ypresian test case.
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Oviposition of the snake Thelotornis kirtlandii in a parabiotic ant nest
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Mitochondrial phylogeography of a widespread sub-saharan murid rodent Aethomyschrysophilus; the role of geographic barriers and paleoclimate in Zambezian region
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The essential role of uncertainty and limited foresight in energy modelling Version 1
- When making techno-economic simulations to evaluate new climate mitigation technologies, a main challenge is to include uncertainty. The added level of complexity often causes uncertainties to be simplified or ignored in calculations, and not addressed in final public communications. This leads to inaccurate policy and investment decisions because probability is an essential aspect of assessing future scenarios. One specific source of uncertainty is the limitation of information available about the future, which is an aspect of everyday life, but simulation-wise a complex issue. It is however essential, because it is inherently tied to understanding semi-optimal decision making. Quite fundamentally, this pleads for stepping away from rather theoretical (partly) deterministic systems, and moving towards realistic limited foresight modelling techniques, such as offered by integrated Monte Carlo calculations.
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Fish otoliths from the Early and Middle Miocene of the Penedès (Catalunya, Spain)
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Animal exploitation at ed-Dur (Umm al-Qaiwain, United Arab Emirates)
- Faunal remains are described from a series of contexts excavated in the coastal site of ed-Dur, dated between the second and fourth century AD. The more than 19,000 identified animal bones allowed a diachronic and spatial analysis. Subsistence relied heavily on domestic animals, in particular sheep and goat, and on fishing. Whereas the exploitation of terrestrial resources seems to have been quite constant throughout the period considered, the aquatic fauna shows changes through time. A shift, possibly linked to overexploitation, is seen both in the proportions of the targeted fish species and in their sizes. The deposition of some of the mammals encountered in burials is also dealt with; dog and ovicaprid can probably be added to the list of mammals used in ritual context in the region. Spatial analysis did not reveal particular concentrations or activity areas. In general the finds fit nicely in the archaeozoological record of the wider region.
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The European Mesonychid Mammals: Phylogeny, Ecology, Biogeography, and Biochronology
- Here we review the fossil record of European mesonychids, which are known only through the genera Dissacus and Pachyaena from Thanetian and Ypresian localities (from MP6 to MP10 reference-levels). We describe two new species, Dissacus rougierae, sp. nov., and Dissacus raslanloubatieri, sp. nov., respectively from Palette (Ypresian, ≈MP7) and from La Borie (Ypresian, ≈MP8 + 9). We also describe new specimens of D. europaeus from Berru (Thanetian, ≈MP6). The evolution of the geographic distribution of the European mesonychids is characterized by three phases: (1) the mesonychid Dissacus appeared in Europe during the Thanetian (≈ 57–58 Mya), probably due to dispersal from North America; D. europaeus survived the PETM event (≈ 56 Mya) and possibly experienced a dwarfism; (2) the large mesonychid Pachyaena migrated into Europe shortly after the Paleocene-Eocene boundary (≈ 55 Mya), but it was restricted to northwestern Europe, while Dissacus is recorded at this time only in southwestern Europe (Palette); and (3) Pachyaena rapidly disappeared from European environments, while Dissacus subsequently dispersed into northwestern Europe (≈ 54–52 Mya). We performed phylogenetic analyses in order to identify the relationships of the new species among mesonychids. It seems that the mesonychids went through two radiative events: the first during the Paleocene, the second mostly during the early Eocene. The first one corresponds to the diversification of Dissacus, while the latter resulted in the appearance of the most specialized mesonychids, such as Pachyaena and Mesonyx.
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Dating the latest appearance of Neanderthals in Belgium
- Belgium represents a key region for studying the Middle to Upper Palaeolithic transition (MUPT) in North-West Europe. This area sits at the crossroads between Palaeolithic cultural facies with influences from eastern, western and southern Europe intermingling during the Late Middle Palaeolithic and the MUPT. Until recently, a temporal gap believed to be around 4ka (ca 42-38 ky calBP) existed between the Late Mousterian and the earliest dated Aurignacian settlements in the region [1, 2]. The dates obtained on Neanderthal remains from Spy fell into this gap, making them the latest Neanderthals in the region [3]. Including the dates from Spy, a gap of two millennia remained between the dates on Neanderthals and the beginning of the Aurignacian. Based on this chronological evidence, the transition from Neanderthals to Anatomically Modern Humans (AMH) in this region was believed to have been without contact between species. AMH would have settled in an area Neanderthals abandoned long before. As part of the PalaeoChron project, we have redated the Neanderthal specimens from Spy (tooth, maxilla and scapula), Engis 2 (skull and tooth) and Fond-de-Forêt (femur), using the compound specific radiocarbon dating method in place at the Oxford Radiocarbon Accelerator Unit. This method is based on the extraction of the amino acid hydroxyproline that occurs in mammalian collagen using preparative liquid chromatography. This method is more efficient than others in eliminating modern carbon contamination such as conservation materials. In this presentation, we report the new radiocarbon dates obtained on the Belgian Neanderthal specimens. These results show how much impact sample preparation can have on the AMS measurement when specimens have been heavily preserved with conservation materials, which is often the case for human remains. These results also now place the Belgian Neanderthal remains from Spy, Engis and Fond-de-Forêt in their proper chronometric context and allow us to refine our understanding of the disappearance of Neanderthals in north-western Europe and integrate this with other evidence for the human occupation of this region during the Palaeolithic.
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The gait of Homo naledi
- Remains of the foot, upper and lower limb, thorax and cranium of Homo naledi present a mosaic of primitive and Homo-like traits. These include curved phalanges in the hands, although a human like wrist and palm, an ape-like thorax with Homo-like vertebrae, and a shoulder girdle indicative of climbing competency. The individual bones of the foot and lower limbs largely seem to show an individual compatible with obligate bipedalism, although the pedal phalanges also show curvature [1,2]. Despite the remarkably voluminous assemblages, the H. naledi remains do not include a complete lower limb confidently ascribed to a single individual. A complete lower limb of H. naledi would be informative in what it could tell us regarding potential locomotion. The aim of this study was to reconstruct the lower limbs of the H. naledi skeleton and analyse the potential gait of H. naledi whilst also reviewing recent work on the functional morphology of H. naledi and how this pertains to inferences about bipedal locomotion. The H. naledi lower limb was constructed using estimated femoral, tibial and fibular lengths from the most complete remains of H. naledi currently available [2,3]. Pelvis remains were too fragmented to reconstruct the pelvis. All transformations were performed in ‘LhpFusionBox’, which is a musculoskeletal software primarily used to analyse gait in clinical contexts, but recently adapted for paleoanthropologists [4]. Estimated lengths were used as a reference to reconstruct the individual bones by using anatomical land-marks (ALs) to scale other H. naledi material to the size of the estimated bones. Both a modern human model and new lower limb associations of a juvenile skeleton found in the Dinaledi chamber were used as guides to reconstruct a complete lower limb. Reconstructions of individual isolated and scaled limb and foot bones were then placed together to have a complete lower limb re- construction taking into account ligaments, muscles and following the orientation of joint surfaces. The entire limb was then fused to a modern human walking motion to analyse potential locomotion. The reconstruction and biomechanical analysis of the H. naledi lower limb largely demonstrates a morphology compatible with obligate bipedalism, with a medial arch (although reduced), elongated limbs, marked bicondylar angle and joint surfaces compatible with bipedal gait. The elongation of the lower limb is generally seen as a marker of obligate bipedalism although the H. naledi limbs are exceptionally elongated relative to the diaphyseal diameter of the long bones and preserved joint proportions. Longer limbs are generally thought of as more energy efficient, but they also require a greater moment of inertia, which increases energy costs. Whilst the longer tibia (and leg) may have necessitated a longer swing phase, low limb mass (as evidenced by long bone gracility and small joints) may have offset this energetically. Other unique traits such as the flaring ilium, flattened femoral lower neck and overall general mix of primitive and Homo-like traits may not have impeded obligate bipedalism, but they may have been advantageous for climbing. Primitive traits are often thought of as vestiges of an ancient past on the way to the modern human form of obligate bipedalism, however, Homo erectus and other skeletons from the genus Homo are largely thought to be fully obligate bipedals from approximately 1.5 million years onwards, and as H. naledi has been dated between 335 and 236ka [5], it is therefore curious why this particular branch of the hominid tree would ‘hang on’ to the ‘primitive traits’ for at least a million years longer. It is therefore likely that this hominin engaged in both arboreal climbing and bipedal walking.
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Doubling the number of high-coverage Neandertal genomes
- Over the last few years, the recovery and the analyses of genomes of ancient modern humans, Neandertals, and Denisovans have changed our understanding of the origins, the movements, and the relatedness of archaic and modern human populations. How- ever, in many cases endogenous DNA represents such a small fraction of the DNA extracted from specimens that sequencing of the complete ancient genomes is economically infeasible. Thus, to date, only three Neandertal genomes have been sequenced to high coverage [1-3]. Even though Neandertal genome sequences of low coverage [4] can be used to reconstruct various aspects of Neandertal genetic history, many analyses, for example estimation of population size and levels of inbreeding, rely on the reliable diploid genotypes. Recent studies have shown that certain skeletal elements, such as the inner part of the petrous bone and the ce- mentum layer in teeth [5 and references therein], may preserve DNA better over time. There is also evidence that the preservation of endogenous DNA may vary substantially even within a few millimeters distance in a single specimen [2, 4]. Due to the value and scarcity of ancient hominin remains, it is critical that the smallest possible amount of destructive sampling is involved in the recovery of genetic material. A usual sampling strategy typically involves taking around 50 mg of powder from a single location of a given bone or tooth. We investigated here whether taking multiple smaller samples in a step-wise manner of the Neandertal specimens from the Mezmaiskaya Cave in Russia and the Troisième caverne of Goyet in Belgium may improve the yield of an- cient human DNA. We removed between 8.5 and 27.2 mg of bone powder from a Mezmaiskaya 1 rib fragment, between 2.5 and 35.1 mg from a Mezmaiskaya 2 skull fragment, and between 5.8 and 53.8 mg from the Goyet Q56-1 femur fragment, amounting to between 15 and 38 powder subsets per specimen and an average input of 16.6 mg of powder per extraction. Importantly, to minimize the impact of contamination, we treated each powder aliquot with 0.5\% sodium hypochlorite solution prior to DNA extraction. The DNA extracts from the same specimen varied by several orders of magnitude in their proportion of endogenous DNA (between 0.07\% and 54.7\%), their content of nuclear genomes (between 0.01 and 78-fold coverage), as well as in the levels of present-day human contamination (0.2-50.3\%). There was no significant correlation between the amount of powder used for the extraction and the overall amount of the endogenous DNA or the levels of present-day human DNA contamination. Thus, these results indicate that ancient DNA preservation varies greatly within one specimen and that the removal of multiple, small sub-samples instead of one larger sample, here coupled with a decontamination procedure, can drastically improve the likelihood of isolating large enough amounts of DNA to make whole genome sequencing feasible. This approach allowed us to identify extracts with exceptionally high endogenous DNA content and low levels of present-day human DNA contamination (2\%), enabling us to generate three additional high-coverage Neandertal genomes. The high-quality genome sequences of multiple Neandertals form a unique reference resource for the scientific community and are valuable for analyses that require reliable diploid genotypes and haplotype information. For example, these data open new opportunities to investigate Neandertal population history, to identify genetic variants that arose uniquely on the Neandertal lineage and might have changed through time, and to determine those that may underlie archaic-specific traits or adaptations.
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Palaeogenomic investigations at the Troisième caverne of Goyet, Belgium
- The main excavations at the Troisième caverne of Goyet in Belgium were conducted by Edouard Dupont in 1868 who identified Palaeolithic human occupations later attributed to the Middle and Upper Palaeolithic. These are represented by an archaeologi- cal record that spans the Mousterian, Lincombian-Ranisian-Jerzmanowician, Aurignacian, Gravettian, and Magdalenian, and then extends into the Neolithic and historic periods. Due to the lack of detailed documentation of the excavated materials, their asso- ciation to a specific chronocultural context has been challenging. Morphometric and taphonomic analyses, combined with direct radiocarbon dating as well as isotopic and genetic analyses, were used to assign human remains to either late Neanderthals or an- cient modern humans from different chronocultural groups. In 2016 the first palaeogenetic investigation of Neanderthal specimens from Goyet was published [1]. Taxonomic assignment was confirmed by performing hybridization capture of the mitochondrial DNA (mtDNA) and later inspecting diagnostic mutations at nucleotide positions that distinguish modern humans from Nean- derthals. Moreover, a phylogenetic reconstruction placed seven nearly complete mtDNA sequences from Goyet within the diver- sity of late Neanderthal mtDNA. An around two-fold coverage nuclear genome was later sequenced from one of those individuals (Goyet Q56-1) [2], revealing a high genetic similarity to other late Neanderthals that is well correlated to their geographical dis- tance. Analyzing modern human remains retrieved at Goyet, mtDNA genomes were initially reported for two specimens directly dated to the Aurignacian, five to the Gravettian, and one to the Magdalenian [3]. Aurignacian-related individuals were particu- larly intriguing as they were found to carry mtDNA haplogroup M, which is almost entirely absent in present-day Europeans. For Gravettian- to Magdalenian-related individuals, the shift from U2/U5 to U8 haplogroups was detected locally - as in other regions of Central Europe - likely influenced by the genetic bottleneck during the Last Glacial Maximum (LGM). Furthermore, nuclear sequences of five modern human individuals from Goyet were produced through genome-wide targeted enrichment [4] revealing local replacement between Aurignacian- and Gravettian-related populations. However, the genetic component associated with a 35,000-year-old individual (Goyet Q116-1) reappeared after the LGM, first in Spain and then in other European regions includ- ing in a Magdalenian-related individual from Goyet (Goyet Q-2). This individual was later found to be the best proxy for a genetic component that was largely displaced in Europe from around 14,000 years ago onwards while surviving in high proportion among Mesolithic individuals from Iberia [5]. Here we present new palaeogenetic data of Neanderthal and modern human individuals from this iconic site. First, we expand the molecular taxonomic identifications with three additional Neanderthal specimens and reconstruct their partial mtDNA genomes. Those confirm the general picture of a limited genetic diversity for late Neanderthals, which is also apparent among the Goyet Neanderthals. Second, working on modern human remains, we produced new mtDNA and nuclear data from four Gravettian specimens. They belong to mtDNA haplogroups U2 and U5, further extending the observa- tion of both mtDNA types being largely present in pre-LGM Europe. Moreover, their nuclear genomes provide additional evidence for the genetic affinity between Gravettian-related groups across Europe, from the present-day regions of the Czech Republic to Belgium and Southern Italy. In conclusion, the deep temporal range covered by the human remains from the Troisième caverne of Goyet provides the unique opportunity to describe within a single archaeological site the major genetic transformations that took place in Europe throughout the Middle and Upper Palaeolithic.
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New Neandertal remains from Trou Magrite, Belgium
- Trou Magrite is a cave site located at Pont-à-Lesse in the Lesse Valley, commune of Dinant, Belgium. It has been known since E. Dupont conducted excavations at the site in 1867 [1]. The most recent fieldwork was done by L. Straus and M. Otte in 1991-92 [2]. Trou Magrite yielded rich lithic assemblages, osseous artifacts, mobiliary art, and numerous faunal remains. Several human re- mains were also recovered and identified as Palaeolithic humans by E. Dupont but have been only partially published thus far. The archaeological record covers a broad time range spanning from the Middle and Upper Palaeolithic to the Mesolithic, Neolithic, and Iron Age. An important Middle Palaeolithic collection is present, probably representing several occupation phases during the Late Pleistocene [2]. Unfortunately, although E. Dupont conducted excavations that can be characterized as modern for that time, the materials from the different so-called “fauna-bearing levels” that he defined in the field were mixed post-excavation [3]. In 2015, we initiated a multidisciplinary re-assessment of the human and faunal collections from Trou Magrite in order to update the inven- tory of human remains already identified, check for the presence of human remains that may have been previously overlooked, and verify their chronocultural context. We revised the already known human collection, conducted a systematic sorting of the faunal material, and combined the use of morphometrics, taphonomy, stable isotopes, dating, and genetic analyses to perform taxonomic and chronocultural identifications. Here we present two previously unidentified Neandertal fossils that we isolated from the Trou Magrite faunal material excavated by E. Dupont in the 19th century. They represent two different individuals: an adult/adolescent, represented by an upper right permanent canine, and a neonate, represented by the diaphysis of a left femur. Whereas no endoge- nous DNA was recovered from the tooth, the palaeogenetic analyses of the neonate femur confirmed its Neandertal status and indicate its sex to be male. We will present the biological characteristics and mitochondrial DNA phylogenetic position of the Trou Magrite Neandertals, in particular with regard to the other Northern European Neandertals. Our project adds Trou Magrite to the list of Belgian sites that have yielded Neandertal fossils and helps to emphasize the importance of the Mosan Basin in Neandertal studies.
