Le registre d’hominines fossiles du bassin de l’Omo-Turkana

L’objectif de cette présentation est de considérer un registre exhaustif d’hominines fossiles comme objet d’étude en tant que tel et de montrer via quelques exemples l’apport de l’analyse d’un tel registre, à condition qu’il provienne d’un système sédimentaire cohérent. Nous illustrerons ceci en utilisant le registre d’hominines du bassin de l’Omo-Turkana (Kenya/Éthiopie), où les recherches paléoanthropologiques intensives ont commencé en 1967. À ce jour, le registre d’hominines fossiles est..

From fossils to mind

Fossil endocasts record features of brains from the past: size, shape, vasculature, and gyrification. These data, alongside experimental and comparative evidence, are needed to resolve questions about brain energetics, cognitive specializations, and developmental plasticity. Through the application of interdisciplinary techniques to the fossil record, paleoneurology has been leading major innovations. Neuroimaging is shedding light on fossil brain organization and behaviors. Inferences about the development and physiology of the brains of extinct species can be experimentally investigated through brain organoids and transgenic models based on ancient DNA. Phylogenetic comparative methods integrate data across species and associate genotypes to phenotypes, and brains to behaviors. Meanwhile, fossil and archeological discoveries continuously contribute new knowledge. Through cooperation, the scientific community can accelerate knowledge acquisition. Sharing digitized museum collections improves the availability of rare fossils and artifacts. Comparative neuroanatomical data are available through online databases, along with tools for their measurement and analysis. In the context of these advances, the paleoneurological record provides ample opportunity for future research. Biomedical and ecological sciences can benefit from paleoneurology's approach to understanding the mind as well as its novel research pipelines that establish connections between neuroanatomy, genes and behavior

Data from: Evidence for a Late Pliocene faunal transition based on a new rodent assemblage from Oldowan locality Hadar A.L. 894, Afar Region, Ethiopia

The time interval between 3-2 Ma marks several important transitions in human evolution, including the extinction of Australopithecus afarensis, the origin of the genus Homo, and the appearance of concentrated stone tool assemblages forming recognizable archaeological sites. The period also marks important changes in Earth's climatic history, with the onset of northern hemisphere glaciation starting sometime between 2.8-2.5 Ma and it remains an unresolved question in paleoanthropology whether or not the global climatic events influenced in whole or in part, local terrestrial paleoenvironments in Africa and, through this, the course of human evolution. Changes in the terrestrial mammalian faunas of East Africa during this time interval are an important source of data about terrestrial paleoenvironments, and it has been argued that during this time period the mammalian faunas of Africa experienced a sudden pulse in the extinction and origination of taxa. The data corroborating this Turnover Pulse Hypothesis derive from both large-mammal and micromammal data, though the fossil record of the former is much more abundant in this interval. New micromammal fossils recovered from ca. 2.4 Ma deposits at locality A.L. 894, low in the Busidima Formation in the Hadar study area of the Afar region, Ethiopia, reveal a significant faunal turnover when compared with previously published material from older 3.2 Ma micromammal assemblages from the Hadar Formation deposits. The results support the hypothesis of a major faunal transition, but larger sample sizes and more extensive temporal sampling are needed to refine the time and rate of change within this interval at Hadar

Deciphering Alterations of Rodent Bones through In Vitro Digestion: An Avenue to Understand Pre-Diagenetic Agents?

Recent taphonomic studies have shown that avian predators such as owls are responsible for most small-mammal fossil accumulations, and that predators cause bone loss and breakage as well as modification to the surface of bones that are preserved. However, the specific physiochemical alterations and the alterations of bone microstructures that predators induce remain poorly understood. In order to better separate and characterize the effects of bone digestion by owls, we performed an experimental study to simulate digestion by a predator. We put fresh rodent long bones into various solutions to simulate the digestive effects of predators. We first tested an acid solution, followed by other solutions containing key enzymes such as trypsin, lipase, and trypsin + lipase. Next, we compared the results of the simulated digestion experiments with partly digested long bones recovered from Tyto alba and Bubo bubo pellets. We observed that acid action alone did not reproduce the modifications observed on bones from owl pellets, while the enzymatic activity (notably trypsin and trypsin + lipase) produced modifications most similar to those observed on the bones from the owl pellets. These results open a promising field of future experimentation to better understand the early diagenetic modification induced in small mammal bones by digestion, which can improve our ability to recognize the role of nocturnal predators in fossil accumulations

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The fossil record of camelids demonstrates a late divergence between Bactrian camel and dromedary

International audienceA new compilation of the Old World fossil record of the Camelidae and a recent phylogenetic analysis allow a new assessment of the timing of the diversification in that taxon. Using a recent implementation of the fossilized birth-death process, we show that the divergence between Bactrian camel and dromedary has a peak probability density around 1 Ma and probably occurred less than 2 million years ago. These dates are much younger than molecular estimates, which place the divergence between the dromedary and the Bactrian camel between 4 and 8 million years ago. Calibration problems in molecular dating seems to explain much of this difference

The Pleistocene Fauna (Other han Primates) from Asbole, Lower Awash Valley, Ethiopia, and Its Environmental and Biochronological Implications

The Asbole area in the Lower Awash Valley yielded a diverse fauna of large and small mammals, associated with an Acheulean industry. The most notable forms are a potentially new species of herpestid, a large collection of Kolpochoerus majus, and the earliest known Bos in Africa. Biochronologically, this fauna belongs to the earliest Middle Pleistocene, and is roughly contemporaneous with the Bodo site further south. Paleoenvironmentally, the fauna suggests a mosaic of landscapes among which humid environments, grasslands and forests, are predominant

First hominin from the Basal Member of the Hadar Formation, Dikika, Ethiopia

http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6WJS-4GNCFYN-1-1&_cdi=6886&_user=10&_orig=browse&_coverDate=10%2F31%2F2005&_sk=999509995&view=c&wchp=dGLbVlb-zSkWz&md5=f23db0256dcc9710ecc1d61cdb267129&ie=/sdarticle.pdfInternational audienceIn this paper we report for the first time hominin remains from the Basal Member of the Hadar Formation atDikika, in the Awash Valley of Ethiopia, dating to greater than 3.4 Ma. The new fossil, DIK-2-1, is a fragment of a leftmandible and associated dentition. The mandible is attributed to Australopithecus afarensis. However, the new fossilexhibits some metric and morphological features that have not previously been seen in the A. afarensis hypodigm,increasing the already impressive degree of variation in the mandibular sample of the species

A New Hominin From the Basal Member of the Hadar Formation, Dikika, Ethiopia, and Its Geological Context

In this paper we report for the first time hominin remains from the Basal Member of the Hadar Formation at Dikika, in the Awash Valley of Ethiopia, dating to greater than 3.4 Ma. The new fossil, DIK-2-1, is a fragment of a left mandible and associated dentition. The mandible is attributed to Australopithecus afarensis. However, the new fossil exhibits some metric and morphological features that have not previously been seen in the A. afarensis hypodigm, increasing the already impressive degree of variation in the mandibular sample of the species

Stratigraphy, Depositional Environments and Basin Structure of the Hadar and Busidima Formations at Dikika, Ethiopia

Sediments exposed in the Dikika Research Project area form a nearly continuous sequence spanning the period from older than 3.8 Ma to younger than 0.15 Ma. By developing a stratigraphic framework of sedimentary basins, we are able to reconstruct a regional geological history that illuminates environmental changes resulting from tectonic events in the Afar triple junction region. The sequence begins with the Basal Member of the Hadar Formation, which was deposited on a dissected and deeply weathered surface of the uppermost flow of Dahla Series Basalt (8–4 Ma). This contact signals an increase in sediment accumulation rate due to active extension along faults parallel to the Red Sea Rift system. Sediments of the Hadar Formation indicate the progressive infilling of the Hadar Basin and migration of the shoreline northward or northeastward toward the axial depocenter, with several brief transgressions southward. After 2.9 Ma, the Dikika Research Project area was uplifted, and the Hadar Formation was faulted and eroded on an angular unconformity. Subsequent to 2.7 Ma, sedimentation returned, although the character and position of the newly developed Busidima half-graben had changed. This basin was formed by the rotation of an asymmetric marginal half-graben around a border fault that paralleled the western escarpment of the Ethiopian Rift. The Busidima Formation deposited in this basin records the migration of the paleo–Awash River across its floodplain in response to a changing tectonic setting. These local paleoenvironmental changes are primarily the response to regional tectonics and are superimposed on the global and regional records of climate change