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Ignacio Torre - One of the best experts on this subject based on the ideXlab platform.
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new excavations in the mnk skull site and the last appearance of the oldowan and homo habilis at Olduvai Gorge tanzania
Journal of Anthropological Archaeology, 2021Co-Authors: Ignacio Torre, Rafael Mora, Michael C Pante, Jackson K. Njau, Lindsay J. Mchenry, Alfonso Benitocalvo, Carmen Martinramos, Ian G StanistreetAbstract:Abstract MNK Skull is one of the most significant archaeological sites in Olduvai Gorge, particularly due to the previous discovery of human fossils referred to in the paper where the Homo habilis taxon was originally defined. An important archaeological assemblage is contained in the same horizon as the hominin fossils, constituting the last evidence of both Homo habilis remains and handaxe-free tool kits in the Olduvai Gorge sequence. Our excavations at the site are the first to be conducted since the original work in the 1960s, and sought to refine the archaeological context wherein the Homo habilis remains were discovered. Chronostratigraphic results place the MNK Skull sequence in Middle Bed II prior to deposition of Tuff IIB. The assemblage was deposited near the shoreline, as Palaeolake Olduvai withdrew into the basinal depocentre, and fossils and stone tools were subjected to significant post-depositional processes. The assemblage was affected by mudflow deposits that buried and preserved the assemblage but also entrained surficial bone and lithic elements into the flow. Rather than an occupation site as originally interpreted, the assemblage is better understood as a background deposit, possibly accumulated on an unconformity surface over a long period of time. The stone tool assemblage is typical of the Oldowan, with no technological elements announcing the appearance of the Acheulean, which is well attested to across the Olduvai sequence in post-Tuff IIB times. Our results highlight that, with an approximate age of circa 1.67 Ma, MNK Skull stands as a key site to understand the late Oldowan and the disappearance of Homo habilis in East Africa.
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pitted stones in the acheulean from Olduvai Gorge beds iii and iv tanzania a use wear and 3d approach
Journal of Human Evolution, 2020Co-Authors: Adrian Arroyo, Ignacio TorreAbstract:Abstract The archaeological sequence of Olduvai Gorge Beds III and IV is essential for the study of the evolution of the African Acheulean between ∼1.3 Ma and 0.6 Ma. However, no further reexaminations of the lithic assemblages have been published after Mary Leakey's original work. In this article, we present an analysis of a part of these collections, with an emphasis on the microscopic and spatial analysis of percussive marks in the so-called pitted stones. To investigate the function of pitted stones and understand the formation process of depressions on lava cobbles, archaeological pitted stones were compared with experimental tools used in bipolar knapping, nut-cracking, and flake-splitting activities. Our results demonstrate that features of pitted stones remained homogeneous across Beds III and IV assemblages, with depressions preferentially located on the central areas of the tools and similar use-wear traces inside such depressions. Comparisons with the experimental collection demonstrate that these depressions are rapidly formed when splitting flakes, resulting in elongated morphologies similar to those documented in the archaeological tools. Our results are discussed within the context of other archaeological and nonhuman primate assemblages to further explore the function of pounding activities in which pitted stones could have potentially been involved.
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raw material optimization and stone tool engineering in the early stone age of Olduvai Gorge tanzania
Journal of the Royal Society Interface, 2020Co-Authors: Alastair J M Key, Tomos Proffitt, Ignacio TorreAbstract:For more than 1.8 million years hominins at Olduvai Gorge were faced with a choice: whether to use lavas, quartzite or chert to produce stone tools. All are available locally and all are suitable for stone tool production. Using controlled cutting tests and fracture mechanics theory we examine raw material selection decisions throughout Olduvai's Early Stone Age. We quantify the force, work and material deformation required by each stone type when cutting, before using these data to compare edge sharpness and durability. Significant differences are identified, confirming performance to depend on raw material choice. When combined with artefact data, we demonstrate that Early Stone Age hominins optimized raw material choices based on functional performance characteristics. Doing so flexibly: choosing raw materials dependent on their sharpness and durability, alongside a tool's loading potential and anticipated use-life. In this way, we demonstrate that early lithic artefacts at Olduvai Gorge were engineered to be functionally optimized cutting tools.
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Large mammal diets and paleoecology across the Oldowan–Acheulean transition at Olduvai Gorge, Tanzania from stable isotope and tooth wear analyses
'Elsevier BV', 2019Co-Authors: Uno, Kevin T., Rivals Florent, Bibi Faysal, Pante Michael, Njau, Jackson K, Ignacio TorreAbstract:The well-dated Pleistocene sediments at Olduvai Gorge have yielded a rich record of hominin fossils, stone tools, and vertebrate faunal remains that, taken together, provide insight to hominin behavior and paleoecology. Since 2008, the Olduvai Geochronology and Archaeology Project (OGAP) has undertaken extensive excavations in Bed II that have yielded a large collection of early Pleistocene stone tools and fossils. The strata of Lower, Middle and Upper Bed II at Olduvai Gorge capture the critical transition from Oldowan to Acheulean technology and therefore provide an opportunity to explore the possible role of biotic and abiotic change during the transition. Here, we analyze newly discovered and existing fossil teeth from Bed II sites using stable isotope and tooth wear methods to investigate the diets of large mammals. We reconstruct the dietary ecology of Bed II mammals and evaluate whether vegetation or hydroclimate shifts are associated with the technological change. Combined isotope and tooth wear data suggest most mammals were C$_4$ grazers or mixed feeders. Carbon isotope data from bulk enamel samples indicate that a large majority of Bed II large mammals analyzed had diets comprising mostly C$_4$ vegetation (>75% of diet), whereas only a small number of individuals had either mixed C$_3$–C$_4$ or mostly C$_3$ diets (
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hominin raw material procurement in the oldowan acheulean transition at Olduvai Gorge
Journal of Human Evolution, 2018Co-Authors: Lindsay J. Mchenry, Ignacio TorreAbstract:The lithic assemblages at the Oldowan-Acheulean transition in Bed II of Olduvai Gorge, Tanzania, represent a wide variety of raw materials reflecting both the diversity of volcanic, metamorphic, and sedimentary source materials available in the Olduvai basin and surroundings and the preferences of the tool-makers. A geochemical and petrographic systematic analysis of lava-derived archaeological stone tools, combined with textural and mineralogical characterization of quartzite, chert, and other metamorphic and sedimentary raw materials from two Middle and Upper Bed II sites, has enabled us to produce a comprehensive dataset and characterization of the rocks employed by Olduvai hominins, which is used here to establish a referential framework for future studies on Early Stone Age raw material provenancing. The use of rounded blanks for most lava-derived artifacts demonstrates that hominins were accessing lava in local stream channels. Most quartzite artifacts appear to derive from angular blocks, likely acquired at the source (predominantly Naibor Soit hill), though some do appear to be manufactured from stream-transported quartzite blanks. Raw material composition of the EF-HR assemblage indicates that Acheulean hominins selected high-quality lavas for the production of Large Cutting Tools. On the other hand, the HWK EE lithic assemblage suggests that raw material selectivity was not entirely based on rock texture, and other factors, such as blank shape and availability of natural angles suitable for flaking, played a major role in Oldowan reduction sequences.
Jackson K. Njau - One of the best experts on this subject based on the ideXlab platform.
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chronostratigraphy and age modeling of pleistocene drill cores from the Olduvai basin tanzania Olduvai Gorge coring project
Palaeogeography Palaeoclimatology Palaeoecology, 2021Co-Authors: Alan L Deino, Ian G Stanistreet, Jackson K. Njau, Lindsay J. Mchenry, Harald Stollhofen, Clifford W Heil, John W King, Joshua MwankundaAbstract:Abstract The Olduvai Gorge Coring Project drilled a total of 611.72 m of core (575.48 m recovered) of mostly fluvio-lacustrine and fan-delta volcaniclastic Pleistocene strata at three sites in the Olduvai Basin, Tanzania, in 2014. We have developed a chronostratigraphic framework for three of the cores based on 40Ar/39Ar dating of core and outcrop volcanic and volcaniclastic units, core paleomagnetic stratigraphy, and tephrochemical correlation between cores and from core to outcrop. This framework is then used to constrain Bayesian stratigraphic age models which permit age estimates for desired core levels with realistic confidence intervals. The age models reveal that the deepest core level reached at 245 mbs is ~2.24 Ma, ~210 kyr older than the oldest strata exposed at Olduvai Gorge. Strata net accretion rates in this early phase of basin history were relatively rapid (57–69 cm/kyr), but decreased within ~250 kyr to ~15 cm/kyr in Lower Bed I. Rates rebounded partially in Upper Bed I, but subsequently declined to
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new excavations in the mnk skull site and the last appearance of the oldowan and homo habilis at Olduvai Gorge tanzania
Journal of Anthropological Archaeology, 2021Co-Authors: Ignacio Torre, Rafael Mora, Michael C Pante, Jackson K. Njau, Lindsay J. Mchenry, Alfonso Benitocalvo, Carmen Martinramos, Ian G StanistreetAbstract:Abstract MNK Skull is one of the most significant archaeological sites in Olduvai Gorge, particularly due to the previous discovery of human fossils referred to in the paper where the Homo habilis taxon was originally defined. An important archaeological assemblage is contained in the same horizon as the hominin fossils, constituting the last evidence of both Homo habilis remains and handaxe-free tool kits in the Olduvai Gorge sequence. Our excavations at the site are the first to be conducted since the original work in the 1960s, and sought to refine the archaeological context wherein the Homo habilis remains were discovered. Chronostratigraphic results place the MNK Skull sequence in Middle Bed II prior to deposition of Tuff IIB. The assemblage was deposited near the shoreline, as Palaeolake Olduvai withdrew into the basinal depocentre, and fossils and stone tools were subjected to significant post-depositional processes. The assemblage was affected by mudflow deposits that buried and preserved the assemblage but also entrained surficial bone and lithic elements into the flow. Rather than an occupation site as originally interpreted, the assemblage is better understood as a background deposit, possibly accumulated on an unconformity surface over a long period of time. The stone tool assemblage is typical of the Oldowan, with no technological elements announcing the appearance of the Acheulean, which is well attested to across the Olduvai sequence in post-Tuff IIB times. Our results highlight that, with an approximate age of circa 1.67 Ma, MNK Skull stands as a key site to understand the late Oldowan and the disappearance of Homo habilis in East Africa.
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biased preservation of pleistocene climate variability proxies at Olduvai Gorge tanzania
Palaeogeography Palaeoclimatology Palaeoecology, 2021Co-Authors: Troy Ferland, Ian G Stanistreet, Jackson K. Njau, Harald Stollhofen, Devon E Colcord, Andrea M Shilling, Simon C Brassell, Kathy SchickAbstract:Abstract Olduvai Gorge in northern Tanzania contains a fossiliferous, well-characterized Pleistocene sedimentary record and provides the opportunity to study the relationships between a changing climate, ecology, and hominin evolution. The Olduvai Gorge Coring Project drilled four cores (1A, 2A, 3A, and 3B) into the depocenter of Paleolake Olduvai in 2014 to achieve increased temporal resolution of local climate and ecological data, and investigate the influence and timing of regional climate and tectonics on local signals. We present high-resolution records of bulk organic carbon isotopes (δ13Corg, ‰) from Cores 2A and 3A, total organic carbon (wt%) from Cores 2A and 3A, and organic carbon‑nitrogen ratios (C:N) from Core 2A. Previous work at Olduvai linked % TOC and δ13Corg to orbitally paced variations in lake depth and ecosystem dynamics from Upper Bed I and Lower Bed II (1.9–1.7 Ma), associated with eccentricity maxima and the presence of a perennial saline-alkaline lake in the basin. Bulk organic geochemical properties in both cores exhibit marked shifts in variance and magnitude at 1.9 and 1.7 Ma. Low % TOC values prior to and following 1.9–1.7 Ma implicate low productivity and/or increased degradation of organic matter, while C:N ratios from Core 2A reflect increased aquatic or bacterial input. Within the 1.9 to 1.7 Ma interval, high % TOC is dominated by terrestrial inputs as evidenced by high C:N ratios, and bulk δ13Corg captures high variability C3–C4 ecosystem dynamics. Climate variability is highest from 1.9–1.7 Ma, but the δ13Corg records are not consistent between Core 2A and Core 3A. From 1.9–1.7 Ma, Core 3A has increased indicators of erosion relative to Core 2A, suggesting a sedimentary aliasing of the δ13Corg record in Core 3A. Outside of the 1.9–1.7 Ma interval, both changes in organic carbon source and preferential preservation of proxies for wet conditions may obscure true climate variability, inviting further investigation into the ability of the Olduvai Gorge sedimentary record to test climate variability hypotheses for hominin evolutionary events.
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A NEW CRANIUM OFCROCODYLUS ANTHROPOPHAGUS FROM Olduvai Gorge, NORTHERN TANZANIA
Università degli Studi di Milano, 2021Co-Authors: Beatrice AzzarÀ, Christopher A. Brochu, Fidelis T Masao, Giovanni Boschian, Massimo Delfino, Dawid A. Iurino, Jackson S. Kimambo, Giorgio Manzi, Sofia Menconero, Jackson K. NjauAbstract:Olduvai Gorge (northern Tanzania) is one of the best known and most iconic palaeontological and archaeological sites in the world. In more than a century of research it has yielded an impressive record of fossils and stone tools which stands as a compendium of human evolution in the context of environmental changes of East Africa in the last 2 Ma. Recent field work in the DK site at Olduvai lead to the retrieval of a partial crocodile cranium nicknamed Black Sun because it was discovered during an annular solar eclipse. The specimen is here described and compared with extinct and extant African crocodylids. The new cranium can be referred to Crocodylus anthropophagus, a Pleistocene species hitherto found only in Olduvai Gorge. Thanks to the good preservation of the skull table, its morphology is here characterised for the first time. Black Sun represents to date the earliest (ca. 1.9–1.85 Ma) and the most informative cranium of C. anthropophagus in the fossil record. Our phylogenetic analysis supports a strict relationship between C. anthropophagus and Crocodylus thorbjarnarsoni, a large species from the Plio-Pleistocene of the Turkana Basin (Kenya). These two sister taxa share a combination of characters which places them at the base of Crocodylus, providing an intriguing element to the debate on the African or extra-African origin of this genus
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core stratigraphy constrains bed iv archaeological record at heb site Olduvai Gorge tanzania
Palaeogeography Palaeoclimatology Palaeoecology, 2020Co-Authors: Michael C Pante, Jackson K. Njau, Nicholas Toth, Edward W Herrmann, Lana Ruck, Paul FarrugiaAbstract:Abstract The Olduvai Gorge deposits contain a rich archaeological record documenting the evolution of hominin behavior over the last 2 million years. While archaeological assemblages in the lower sedimentary layers (Beds I-II) are well preserved in relatively secure chronostratigraphic contexts, the age of overlying beds is poorly constrained due to discontinuous exposures and lack of marker horizons, abundant erosional contacts and lack of unweathered, dateable material. As a result, Beds III-IV and the Masek Beds, have yet received little attention compared to the underlying beds. Recently, the Olduvai Gorge Coring Project (OGCP) acquired high resolution, stratigraphically continuous sedimentary cores of Palaeolake Olduvai through scientific drilling, in order to improve the geological and palaeoenvironmental contexts of the hominin record. While other studies reported in this volume have used palaeoenvironmental datasets from the cores to refine the Beds I-II records, this study combines outcrop and core stratigraphic methods to improve the chronology of Bed IV archaeological sites. Our recent excavation at HEB site demonstrates the importance of this approach to improve the stratigraphic positioning and relative age of Bed IV archaeological materials. Our results suggest that the HEB site is younger than previously thought because it was formed after depositional fill of an incised valley, which substantially removed much of lowermost Bed IV in the HEB area. The lithofacies at this site indicate lake expansion and development of Ngorongoro Highland sourced braided streams near the lakeshore at this time, which coincided with rich assemblages of artifacts, fossil fauna, and bones bearing butchery marks. This setting likely afforded a variety of resources to hominins including potable water, raw materials, refuge trees, and animal food, making HEB an important site for inferring the cultural and feeding behaviors of Homo erectus.
Enrique Baquedano - One of the best experts on this subject based on the ideXlab platform.
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tracing the spatial imprint of oldowan technological behaviors a view from ds bed i Olduvai Gorge tanzania
PLOS ONE, 2021Co-Authors: Fernando Diezmartin, David Uribelarrea, Audax Mabulla, Enrique Baquedano, Lucia Cobosanchez, Adrian Baddeley, Manuel DominguezrodrigoAbstract:DS (David's site) is one of the new archaeological sites documented in the same paleolandscape in which FLK 22 was deposited at about 1.85 Ma in Olduvai Gorge. Fieldwork in DS has unearthed the largest vertically-discrete archaeological horizon in the African Pleistocene, where a multi-cluster anthropogenic accumulation of fossil bones and stone tools has been identified. In this work we present the results of the techno-economic study of the lithic assemblage recovered from DS. We also explore the spatial magnitude of the technological behaviors documented at this spot using powerful spatial statistical tools to unravel correlations between the spatial distributional patterns of lithic categories. At DS, lavas and quartzite were involved in different technological processes. Volcanic materials, probably transported to this spot from a close source, were introduced in large numbers, including unmodified materials, and used in percussion activities and in a wide variety of reduction strategies. A number of volcanic products were subject to outward fluxes to other parts of the paleolandscape. In contrast, quartzite rocks were introduced in smaller numbers and might have been subject to a significantly more intense exploitation. The intra-site spatial analysis has shown that specialized areas cannot be identified, unmodified materials are not randomly distributed, percussion and knapping categories do not spatially overlap, while bipolar specimens show some sort of spatial correlation with percussion activities.
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A faltering origin for the Acheulean? Technological and cognitive implications from FLK West (Olduvai Gorge, Tanzania)
Quaternary International, 2019Co-Authors: Fernando Diez-martín, Cristina Fraile, Policarpo Sánchez-yustos, Javier Duque, Thomas Wynn, S Francisco, David Uribelarrea, Audax Mabulla, Enrique Baquedano, Manuel Domínguez-rodrigoAbstract:Abstract The discovery in FLK West lowermost level 6 (Olduvai Gorge, Tanzania) of a massive and symmetrical handaxe, at odds both with the other LCT specimens so far unearthed from this site and with the technological traits commonly reported for the earliest Acheulean ca. 1.7 Ma, challenges the hypothesis of a gradual development of technological and cognitive qualities during the Acheulean. This thought-provoking specimen points to a less sharp difference between the first and later phases of the Early Acheulean (i.e. between ca. 1.7 and 1.2 Ma) and supports a somewhat punctuated flourishing of the handaxe technical and cognitive conceptualization. In this regard, this paper provides a detailed descriptive study of the large olivine basalt handaxe, in the framework of both the FLK West L6 lithic collection and the LCT shaping strategies. This analysis includes a morphometric description of the specimen and a comprehensive analysis of the knapping and shaping sequencing, through a diacritical study. It also includes a techno-functional assessment of the final design and symmetry. Finally, this paper examines some of the most significant implications of this large tool for our current views on temporal divisions within the African Acheulean and the cognitive abilities of the individual that made it.
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a use wear interpretation of the most common raw materials from the Olduvai Gorge naibor soit quartzite
Quaternary International, 2019Co-Authors: Patricia Belloalonso, Manuel Dominguezrodrigo, Alfredo Perezgonzalez, Enrique Baquedano, Joseba Riosgaraizar, Joaquin Panera, Susana Rubiojara, Raquel Rojasmendoza, Manuel SantonjaAbstract:Abstract This paper presents for the first time an experimental protocol for the assessment of use-wear produced when using Precambrian and metamorphic white Naibor Soit quartzite (NQ) flakes. NQ is the most recurrent raw material from the archaeological sites of the Olduvai Gorge during the Early Stone Age (ESA). The objective of this study is to provide a preliminary description of the experimentally produced use-wear traces that can be applied to the analysis of sites like the Acheulean site of Thiongo Korongo (TK, Olduvai Gorge, Tanzania) or other sites from Olduvai where NQ was used to tool production. This experimental protocol incorporates a broad range to tasks including plant processing (underground storage organs [USOs], wood, herbaceous plants, and canes) and carcass processing (butchery and bone processing). The most novel activity of this experimental protocol is the processing of USOs. For this we have replicated different steps of tuber processing including the cutting, peeling, and scraping of five varieties of USOs (Beta vulgaris, Daucus carota, Ipomoea batatas, Pastinaca sativa and Zingiber, officinale) with differences in hardness, fibrosity, water content, and peel regularity. After analysing micro and macro-wear traces on the experimental flakes, several criteria for distinguishing between different activities (scraping, cutting, peeling, sawing, cutting, butchery) and the different materials being processed were identified. These criteria are based on the presence, continuity, and morphology of macro-scars along with the presence, distribution, nature, and intensity of different micro traces (micro-scars, attrition, striations, pits, rounding, polish). Additionally, we have identified several processes that limit the formation of traces, including the tendency of some activities to weaken NQ edges and shorten the duration of use.
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a geoarchaeological reassessment of the co occurrence of the oldest acheulean and oldowan in a fluvial ecotone from lower middle bed ii 1 7ma at Olduvai Gorge tanzania
Quaternary International, 2019Co-Authors: David Uribelarrea, Fernando Diezmartin, David Martin Perea, Rebeca Barba, Agnes Gidna, Audax Mabulla, Enrique Baquedano, Manuel DominguezrodrigoAbstract:Abstract The coexistence of the oldest Acheulean and Oldowan industries means that the appearance of the former cannot be due to an anagenetic development from the latter. At Olduvai Gorge, Tanzania, both industries are found within the same chronostratigraphic unit, the Lower Augitic Sandstone (LAS; 1.7 Ma), at HWK, HWK-E, HWK-EE (Oldowan) and FLK-W and FLK-N (Acheulean). Recently, McHenry and Stanistreet (2018) and Stanistreet et al. (2018) have argued that the Acheulean site of FLK West is actually located within a more recent stratigraphic unit, the Middle Augitic Sandstone (MAS). If so, the Acheulean could potentially have evolved from the Oldowan anagenetically. We test this hypothesis by reviewing the stratigraphy of the LAS from the HWK area to the FLK-W site. Hay's (1976) previous work stresses the continuity of the LAS from HWK-EE to FLK-NN, and stratigraphic and sedimentological evidence indicates that while the MAS has eroded away, the LAS is continuous throughout the study area. According to Hay (1976), Uribelarrea et al. (2017) and this work, the LAS is present at HWK-EE, HWK-E, HWK, HWK-W, FLK-S, FLK-W, FLK-N and FLK-NN. The emergence of the Acheulean at Olduvai Gorge ca. 1.7Ma and its coexistence with the Oldowan thus demonstrates a cladogenetic, rather than an anagenetic, origin for the Acheulean. This has implications for the behavioral and biological interpretations of the origin and co-existence of both types of industries.
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who ate oh80 Olduvai Gorge tanzania a geometric morphometric analysis of surface bone modifications of a paranthropus boisei skeleton
Quaternary International, 2019Co-Authors: Julia Aramendi, Agnes Gidna, Audax Mabulla, Mari Carmen Arriaza, Jose Yravedra, Miguel Angel Mategonzalez, Maria Cruz Ortega, Lloyd A Courtenay, Diego Gonzalezaguilera, Enrique BaquedanoAbstract:Olduvai Gorge (Tanzania) is one of the key areas for the study of human origins, given the sheer abundance of archaeological and paleontological sites discovered. Several of these archaeological sites have yielded numerous hominin fossils and traces of their activities, thus offering invaluable insights into the nature and origins of human behavior. Nevertheless, certain taphonomic discussions that have been of great importance for the study of the South African cave sites have remained unnoticed in East Africa. One of these issues revolves around the interpretation of Paranthropus as a common prey of predators. In this paper, we analyze the postcranial remains of OH80, a partial skeleton of a Paranthropus boisei discovered at the BK site (Bell Korongo, Bed II of Olduvai Gorge, Tanzania) in 2010. Some of the specimens of this skeleton have been reported to show surface modifications tentatively associated to the action of carnivores. Here, several pits observed on OH80-12, the Paranthropus boisei femur, were digitally reconstructed and analyzed through geometric morphometrics to determine the nature of the marks. The OH80-12 marks are compared with a modern sample of percussion marks and several carnivore tooth pits, since the action of both agents has previously been identified at the site and can sometimes result in equifinality problems. Alongside already published geometric morphometric tests, here we present a very newly developed approach based on the combination of geometric morphometric data and the training of machine learning algorithms. Both methodologies highlight that OH80 was consumed by carnivores, being a felid the most likely modifying agent.
Michael C Pante - One of the best experts on this subject based on the ideXlab platform.
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new excavations in the mnk skull site and the last appearance of the oldowan and homo habilis at Olduvai Gorge tanzania
Journal of Anthropological Archaeology, 2021Co-Authors: Ignacio Torre, Rafael Mora, Michael C Pante, Jackson K. Njau, Lindsay J. Mchenry, Alfonso Benitocalvo, Carmen Martinramos, Ian G StanistreetAbstract:Abstract MNK Skull is one of the most significant archaeological sites in Olduvai Gorge, particularly due to the previous discovery of human fossils referred to in the paper where the Homo habilis taxon was originally defined. An important archaeological assemblage is contained in the same horizon as the hominin fossils, constituting the last evidence of both Homo habilis remains and handaxe-free tool kits in the Olduvai Gorge sequence. Our excavations at the site are the first to be conducted since the original work in the 1960s, and sought to refine the archaeological context wherein the Homo habilis remains were discovered. Chronostratigraphic results place the MNK Skull sequence in Middle Bed II prior to deposition of Tuff IIB. The assemblage was deposited near the shoreline, as Palaeolake Olduvai withdrew into the basinal depocentre, and fossils and stone tools were subjected to significant post-depositional processes. The assemblage was affected by mudflow deposits that buried and preserved the assemblage but also entrained surficial bone and lithic elements into the flow. Rather than an occupation site as originally interpreted, the assemblage is better understood as a background deposit, possibly accumulated on an unconformity surface over a long period of time. The stone tool assemblage is typical of the Oldowan, with no technological elements announcing the appearance of the Acheulean, which is well attested to across the Olduvai sequence in post-Tuff IIB times. Our results highlight that, with an approximate age of circa 1.67 Ma, MNK Skull stands as a key site to understand the late Oldowan and the disappearance of Homo habilis in East Africa.
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core stratigraphy constrains bed iv archaeological record at heb site Olduvai Gorge tanzania
Palaeogeography Palaeoclimatology Palaeoecology, 2020Co-Authors: Michael C Pante, Jackson K. Njau, Nicholas Toth, Edward W Herrmann, Lana Ruck, Paul FarrugiaAbstract:Abstract The Olduvai Gorge deposits contain a rich archaeological record documenting the evolution of hominin behavior over the last 2 million years. While archaeological assemblages in the lower sedimentary layers (Beds I-II) are well preserved in relatively secure chronostratigraphic contexts, the age of overlying beds is poorly constrained due to discontinuous exposures and lack of marker horizons, abundant erosional contacts and lack of unweathered, dateable material. As a result, Beds III-IV and the Masek Beds, have yet received little attention compared to the underlying beds. Recently, the Olduvai Gorge Coring Project (OGCP) acquired high resolution, stratigraphically continuous sedimentary cores of Palaeolake Olduvai through scientific drilling, in order to improve the geological and palaeoenvironmental contexts of the hominin record. While other studies reported in this volume have used palaeoenvironmental datasets from the cores to refine the Beds I-II records, this study combines outcrop and core stratigraphic methods to improve the chronology of Bed IV archaeological sites. Our recent excavation at HEB site demonstrates the importance of this approach to improve the stratigraphic positioning and relative age of Bed IV archaeological materials. Our results suggest that the HEB site is younger than previously thought because it was formed after depositional fill of an incised valley, which substantially removed much of lowermost Bed IV in the HEB area. The lithofacies at this site indicate lake expansion and development of Ngorongoro Highland sourced braided streams near the lakeshore at this time, which coincided with rich assemblages of artifacts, fossil fauna, and bones bearing butchery marks. This setting likely afforded a variety of resources to hominins including potable water, raw materials, refuge trees, and animal food, making HEB an important site for inferring the cultural and feeding behaviors of Homo erectus.
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large mammal diets and paleoecology across the oldowan acheulean transition at Olduvai Gorge tanzania from stable isotope and tooth wear analyses
Journal of Human Evolution, 2018Co-Authors: Florent Rivals, Michael C Pante, Jackson K. Njau, Faysal Bibi, Ignacio TorreAbstract:Abstract The well-dated Pleistocene sediments at Olduvai Gorge have yielded a rich record of hominin fossils, stone tools, and vertebrate faunal remains that, taken together, provide insight to hominin behavior and paleoecology. Since 2008, the Olduvai Geochronology and Archaeology Project (OGAP) has undertaken extensive excavations in Bed II that have yielded a large collection of early Pleistocene stone tools and fossils. The strata of Lower, Middle and Upper Bed II at Olduvai Gorge capture the critical transition from Oldowan to Acheulean technology and therefore provide an opportunity to explore the possible role of biotic and abiotic change during the transition. Here, we analyze newly discovered and existing fossil teeth from Bed II sites using stable isotope and tooth wear methods to investigate the diets of large mammals. We reconstruct the dietary ecology of Bed II mammals and evaluate whether vegetation or hydroclimate shifts are associated with the technological change. Combined isotope and tooth wear data suggest most mammals were C4 grazers or mixed feeders. Carbon isotope data from bulk enamel samples indicate that a large majority of Bed II large mammals analyzed had diets comprising mostly C4 vegetation (>75% of diet), whereas only a small number of individuals had either mixed C3–C4 or mostly C3 diets (
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the paleoecology of pleistocene birds from middle bed ii at Olduvai Gorge tanzania and the environmental context of the oldowan acheulean transition
Journal of Human Evolution, 2018Co-Authors: Kari A Prassack, Michael C Pante, Jackson K. Njau, Ignacio TorreAbstract:Abstract Fossil bird data (community composition and taphonomic profiles) are used here to infer the environmental context of the Oldowan-Acheulean transitional period at Olduvai Gorge, Tanzania. This is the first comprehensive report on the Middle Bed II avifauna and includes fossils excavated by the Olduvai Geochronology and Archaeology Project (OGAP) and recently rediscovered fossils collected by Mary Leakey. Crane, ibis, darter, owl, raptor, crow, and vulture are reported from Bed II for the first time. The presence of these taxa, absent earlier in this Bed, point to a general opening and drying of the landscape with grassland and open woodland expansion. Taxa associated with dense, emergent wetland vegetation, such as dabbling ducks and rails, are uncommon and less diverse than earlier in Bed II. This suggests more mature wetlands with clearer waters. Cormorants continue to be common, but are less diverse. Cormorants and other roosting taxa provide evidence of trees in the area. Compared to lowermost Bed II, the Middle to Upper Bed II landscape is interpreted here as more open and drier (but not necessarily more arid), with matured wetlands, scattered trees, and a greater expansion of grasslands.
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new excavations at the hwk ee site archaeology paleoenvironment and site formation processes during late oldowan times at Olduvai Gorge tanzania
Journal of Human Evolution, 2017Co-Authors: Ignacio Torre, Rafael Mora, Adrian Arroyo, Michael C Pante, Jackson K. Njau, Lindsay J. Mchenry, Rosa M Albert, Richard I Macphail, Carlos A Riverarondon, Agata RodriguezcintasAbstract:This paper reports the results of renewed fieldwork at the HWK EE site (Olduvai Gorge, Tanzania). HWK EE is positioned across the boundary between Lower and Middle Bed II, a crucial interval for studying the emergence of the Acheulean at Olduvai Gorge. Our excavations at HWK EE have produced one of the largest collections of fossils and artefacts from any Oldowan site, distributed across several archaeological units and a large excavation surface in four separate trenches that can be stratigraphically correlated. Here we present the main stratigraphic and archaeological units and discuss site formation processes. Results show a great density of fossils and stone tools vertically through two stratigraphic intervals (Lemuta and Lower Augitic Sandstone) and laterally across an area of around 300 m2, and highlight the confluence of biotic and abiotic agents in the formation of the assemblage. The large size and diversity of the assemblage, as well as its good preservation, qualify HWK EE as a reference site for the study of the late Oldowan at Olduvai Gorge and elsewhere in Africa. In addition, the description of the stratigraphic and archaeological sequence of HWK EE presented in this paper constitutes the foundation for further studies on hominin behavior and paleoecology in Lower and Middle Bed II.
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chronostratigraphy and age modeling of pleistocene drill cores from the Olduvai basin tanzania Olduvai Gorge coring project
Palaeogeography Palaeoclimatology Palaeoecology, 2021Co-Authors: Alan L Deino, Ian G Stanistreet, Jackson K. Njau, Lindsay J. Mchenry, Harald Stollhofen, Clifford W Heil, John W King, Joshua MwankundaAbstract:Abstract The Olduvai Gorge Coring Project drilled a total of 611.72 m of core (575.48 m recovered) of mostly fluvio-lacustrine and fan-delta volcaniclastic Pleistocene strata at three sites in the Olduvai Basin, Tanzania, in 2014. We have developed a chronostratigraphic framework for three of the cores based on 40Ar/39Ar dating of core and outcrop volcanic and volcaniclastic units, core paleomagnetic stratigraphy, and tephrochemical correlation between cores and from core to outcrop. This framework is then used to constrain Bayesian stratigraphic age models which permit age estimates for desired core levels with realistic confidence intervals. The age models reveal that the deepest core level reached at 245 mbs is ~2.24 Ma, ~210 kyr older than the oldest strata exposed at Olduvai Gorge. Strata net accretion rates in this early phase of basin history were relatively rapid (57–69 cm/kyr), but decreased within ~250 kyr to ~15 cm/kyr in Lower Bed I. Rates rebounded partially in Upper Bed I, but subsequently declined to
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new excavations in the mnk skull site and the last appearance of the oldowan and homo habilis at Olduvai Gorge tanzania
Journal of Anthropological Archaeology, 2021Co-Authors: Ignacio Torre, Rafael Mora, Michael C Pante, Jackson K. Njau, Lindsay J. Mchenry, Alfonso Benitocalvo, Carmen Martinramos, Ian G StanistreetAbstract:Abstract MNK Skull is one of the most significant archaeological sites in Olduvai Gorge, particularly due to the previous discovery of human fossils referred to in the paper where the Homo habilis taxon was originally defined. An important archaeological assemblage is contained in the same horizon as the hominin fossils, constituting the last evidence of both Homo habilis remains and handaxe-free tool kits in the Olduvai Gorge sequence. Our excavations at the site are the first to be conducted since the original work in the 1960s, and sought to refine the archaeological context wherein the Homo habilis remains were discovered. Chronostratigraphic results place the MNK Skull sequence in Middle Bed II prior to deposition of Tuff IIB. The assemblage was deposited near the shoreline, as Palaeolake Olduvai withdrew into the basinal depocentre, and fossils and stone tools were subjected to significant post-depositional processes. The assemblage was affected by mudflow deposits that buried and preserved the assemblage but also entrained surficial bone and lithic elements into the flow. Rather than an occupation site as originally interpreted, the assemblage is better understood as a background deposit, possibly accumulated on an unconformity surface over a long period of time. The stone tool assemblage is typical of the Oldowan, with no technological elements announcing the appearance of the Acheulean, which is well attested to across the Olduvai sequence in post-Tuff IIB times. Our results highlight that, with an approximate age of circa 1.67 Ma, MNK Skull stands as a key site to understand the late Oldowan and the disappearance of Homo habilis in East Africa.
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biased preservation of pleistocene climate variability proxies at Olduvai Gorge tanzania
Palaeogeography Palaeoclimatology Palaeoecology, 2021Co-Authors: Troy Ferland, Ian G Stanistreet, Jackson K. Njau, Harald Stollhofen, Devon E Colcord, Andrea M Shilling, Simon C Brassell, Kathy SchickAbstract:Abstract Olduvai Gorge in northern Tanzania contains a fossiliferous, well-characterized Pleistocene sedimentary record and provides the opportunity to study the relationships between a changing climate, ecology, and hominin evolution. The Olduvai Gorge Coring Project drilled four cores (1A, 2A, 3A, and 3B) into the depocenter of Paleolake Olduvai in 2014 to achieve increased temporal resolution of local climate and ecological data, and investigate the influence and timing of regional climate and tectonics on local signals. We present high-resolution records of bulk organic carbon isotopes (δ13Corg, ‰) from Cores 2A and 3A, total organic carbon (wt%) from Cores 2A and 3A, and organic carbon‑nitrogen ratios (C:N) from Core 2A. Previous work at Olduvai linked % TOC and δ13Corg to orbitally paced variations in lake depth and ecosystem dynamics from Upper Bed I and Lower Bed II (1.9–1.7 Ma), associated with eccentricity maxima and the presence of a perennial saline-alkaline lake in the basin. Bulk organic geochemical properties in both cores exhibit marked shifts in variance and magnitude at 1.9 and 1.7 Ma. Low % TOC values prior to and following 1.9–1.7 Ma implicate low productivity and/or increased degradation of organic matter, while C:N ratios from Core 2A reflect increased aquatic or bacterial input. Within the 1.9 to 1.7 Ma interval, high % TOC is dominated by terrestrial inputs as evidenced by high C:N ratios, and bulk δ13Corg captures high variability C3–C4 ecosystem dynamics. Climate variability is highest from 1.9–1.7 Ma, but the δ13Corg records are not consistent between Core 2A and Core 3A. From 1.9–1.7 Ma, Core 3A has increased indicators of erosion relative to Core 2A, suggesting a sedimentary aliasing of the δ13Corg record in Core 3A. Outside of the 1.9–1.7 Ma interval, both changes in organic carbon source and preferential preservation of proxies for wet conditions may obscure true climate variability, inviting further investigation into the ability of the Olduvai Gorge sedimentary record to test climate variability hypotheses for hominin evolutionary events.
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palaeovegetation changes recorded in palaeolake Olduvai ogcp core 2a 2 09 2 12 ma naibor soit formation Olduvai Gorge tanzania
Palaeogeography Palaeoclimatology Palaeoecology, 2020Co-Authors: Agata Rodriguezcintas, Ian G Stanistreet, Harald Stollhofen, Marion K Bamford, Rosa M Albert, Jeffery R Stone, C RiverarondonAbstract:Abstract For five decades Olduvai Gorge has been a key site to reconstruct and understand the relationship between environmental and landscape conditions and use of affordances by early African hominin populations. Following the first Olduvai Gorge Coring project (OGCP) during 2014, a multiproxy microbiological analysis, which includes phytoliths, pollen, diatoms, sponge spicules and chrysophyte cysts, was undertaken on samples collected from various borehole cores. The aim of the study is to better understand palaeoenvironmental and palaeovegetation conditions and changes through time and their relationship to hominin presence and evolution. This study details the first palaeobotanical and palaeoenvironmental study of Borehole 2A at Olduvai Gorge. It represents the as yet oldest known sedimentary sequence in the Olduvai Basin for a portion of the pre-Bed I Naibor Soit Formation; this is a unit that is not accessible in any natural exposures in Olduvai Gorge, and has only recently been encountered by drilling. Here we present the results from a particularly phytolith-prone portion between ~2.09 Ma and 2.12 Ma. Phytolith results indicate a savannah environment dominated by grasses, where Poaceae were a key component and where the C3 Pooideae grasses were mostly dominant, alternating with C4 grasses. Oscillations between grass subfamilies, C3 Pooideae, C4 Chloridoideae, and C4 Panicoideae to lesser degrees, indicate five substantial climatic shifts, varying between more humid and arid conditions. Associated with phytoliths, freshwater indicators such as diatoms, sponge spicules and chrysophyte cysts were also identified, suggesting the presence of wetlands in the lake catchment area. Pollen is extremely rare in the sediments but when present, comprises fungal spores and Poaceae pollen, thus supporting the wetland and grassland reconstructions, respectively. These results offer for the first time, a whole picture of the palaeovegetation and associated palaeoenvironments for this pre-Bed I period. Together with previous results from other areas and chronological periods, they improve our understanding of the evolution and adaptation of early hominins and their close relationship to the surrounding landscape.
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tuff fingerprinting and correlations between ogcp cores and outcrops for pre bed i and beds i ii at Olduvai Gorge tanzania
Palaeogeography Palaeoclimatology Palaeoecology, 2020Co-Authors: Lindsay J. Mchenry, Ian G Stanistreet, Jackson K. Njau, Harald Stollhofen, Nicholas Toth, Kathy SchickAbstract:Abstract Sediment cores retrieved from the Pleistocene Olduvai Basin by the Olduvai Gorge Coring Project (OGCP) provide a high resolution record of tuffs and other volcaniclastic deposits, together with a lacustrine sedimentary record full of paleoenvironmental indicators. Correlating tuffs between the cores and outcrops at Olduvai, where these tuffs are identified at paleoanthropologically important sites, is critical for applying the new paleoenvironmental data to the conditions under which hominins lived. Tuffs and other volcaniclastic deposits from three cores were analyzed for mineral assemblages and glass and mineral major element compositions (feldspar, augite, hornblende, titanomagnetite, and glass where possible) to compare to published geochemical fingerprint data, based on marker tuffs from outcrop equivalents at Olduvai Gorge. In combination with stratigraphic position, these mineralogical and geochemical data were used to correlate between the cores and outcrops, providing direct temporal tie-lines between the cores and sites of paleoanthropological interest. Direct correlations are most certain for Olduvai Bed I, where all major tuff markers from outcrop are identified for one or more of the three core sites, and for the upper part of the underlying Ngorongoro Formation, which includes the Coarse Feldspar Crystal Tuff (CFCT) and Naabi ignimbrites exposed in the oldest Pleistocene exposures of the Western Gorge. Also characterized were the mineral and glass compositions of tuffs and ignimbrites pre-dating the oldest exposed outcrop units, extending our record of explosive events from the Ngorongoro Volcano. While no specific correlations can be confirmed between individual Bed II tuffs in the cores and in outcrops, correlations are possible between the cores themselves (using newly identified tuff compositions), and some potential correlations (non-unique, based on individual mineral phases) between core and outcrop can be used in conjunction with other stratigraphic tools to help constrain the intervals in question.
