Integrative geochronology calibrates the Middle and Late Stone Ages of Ethiopia’s Afar Rift

The Halibee member of the Upper Dawaitoli Formation of Ethiopia’s Middle Awash study area features a wealth of Middle and Later Stone Age (MSA and LSA) paleoanthropological resources in a succession of Pleistocene sediments. We introduce these artifacts and fossils, and determine their chronostratigraphic placement via a combination of established radioisotopic methods and a recently developed dating method applied to ostrich eggshell (OES). We apply the recently developed 230Th/U burial dating of OES to bridge the temporal gap between radiocarbon (14C) and 40Ar/39Ar ages for the MSA and provide 14C ages to constrain the younger LSA archaeology and fauna to ∼24 to 21.4 ka. Paired 14C and 230Th/U burial ages of OES agree at ∼31 ka for an older LSA locality, validating the newer method, and in turn supporting its application to stratigraphically underlying MSA occurrences previously constrained only by a maximum 40Ar/39Ar age. Associated fauna, flora, and Homo sapiens fossils are thereby now fixed between 106 ± 20 ka and 96.4 ± 1.6 ka (all errors 2σ). Additional 40Ar/39 results on an underlying tuff refine its age to 158.1 ± 11.0 ka, providing a more precise minimum age for MSA lithic artifacts, fauna, and H. sapiens fossils recovered ∼9 m below it. These results demonstrate how chronological control can be obtained in tectonically active and stratigraphically complex settings to precisely calibrate crucial evidence of technological, environmental, and evolutionary changes during the African Middle and Late Pleistocene.

Early Pleistocene−to−present paleoclimate archive for the American Southwest from Stoneman Lake, Arizona, USA

Long, continuous records of terrestrial paleoclimate offer insights into natural climate variability and provide context for geomorphological studies, climate model reconstructions, and predictions of future climate change. STL14 is an 80 m lacustrine sediment core that archives paleoenvironmental changes at Stoneman Lake, Coconino County, Arizona, from the early Pleistocene (ca. 1.3 Ma) to present. Full-core sedimentology was analyzed using smear slides and core face observations. Lithofacies strongly correlate with wet bulk density and bulk magnetic susceptibility (MS), and these data resemble a sawtooth pattern characteristic of glacial-interglacial climate cycles. A linkage between deep to shallow lake depth transitions and glacial terminations is supported by an age model that incorporates accelerator mass spectrometry radiocarbon dates and tephrochronology of ashes from the Lava Creek B and multiple Long Valley, California, volcanic eruptions. We correlated middle and late Pleistocene glacial maxima to deep lake deposits defined by well-preserved bedding, increased biosilica, boreal pollen taxa (i.e., Picea), and lower density and MS. Interglacial periods are associated with shallow-water deposits characterized by banded-to-massive siliciclastic material, some authigenic calcite, the alga Phacotus, and higher density and MS. Prior to the marine isotope stage (MIS) 24−22 interval, smaller-amplitude changes in the lake environment suggest milder glacial conditions compared to those of the middle and late Pleistocene. Thus, abrupt intensification of glacial conditions may have occurred ca. 900 ka in the American Southwest, mirroring a global characteristic of the mid-Pleistocene transition. The STL14 record suggests that lake environments throughout the history of this small (3.5 km2), internally drained, basaltic catchment are sensitive to the regional hydrologic balance, which, at orbital time scales, is largely influenced by the northern cryosphere and associated changes in atmospheric circulation. The predominance of quartz in sediment throughout the record indicates significant eolian inputs. Few paleoclimate records from this region extend beyond the last glacial cycle, let alone the middle Pleistocene, making STL14 a valuable resource for studying environmental responses to a range of natural climate states and transitions throughout much of the Quaternary.

Variability of the lower incisors in the cave bears (Carnivora, Ursidae) from the Caucasus and Urals

Morphometric and morphotypic variability of the cave bear lower incisors from two different geographic regions (Caucasus and Urals), different stratigraphic periods (Middle and Late Pleistocene), and bearing different mitochondrial haplogroups (kudarensis (Baryshnikov, 1985) and ingressus Rabeder, Hofreiter & Withalm, 2004) was studied. Urals Ursus kanivetz Vereshchagin, 1973 is clearly distinguished from Caucasian U. kudarensis by morphology of the upper and lower incisors. The Urals cave bear exhibits more derived features compared to the Caucasian cave bears. Ursus kanivetz exhibits the largest average size of the lower incisors. The lower incisors of U. kanivetz are clearly distinct from those in U. kudarensis. Also, U. kudarensis specimens display a clear separation from all other groups of cave bears. Morphology of the incisors of the cave bears is clearly different from that of Early Pleistocene U. etruscus G. Cuvier, 1823, as well as from that of recent U. arctos L., 1758 (Rabeder, 1999) and U. maritimus Phipps, 1774. Our results suggest that the incisors of the cave bears are similar to each other and demonstrate a hypocarnivorous adaptation as a major evolution trend in the lineage of Spelearctos group. These adaptation features were perhaps developed in parallel in different lineages of the cave bears (U. spelaeus Rosenmüller, 1794 and U. kanivetz on the one hand and U. kudarensis on the other hand) in the Late Pleistocene.

Characterization of metapopulation of Ellobium chinense through Pleistocene expansions and four covariate COI guanine-hotspots linked to G-quadruplex conformation

The land snail Ellobium chinense (L. Pfeiffer, 1855) (Eupulmonata, Ellobiida, Ellobiidae), which inhabits the salt marshes along the coastal areas of northwestern Pacific, is an endangered species on the IUCN Red List. Over recent decades, the population size of E. chinense has consistently decreased due to environmental interference caused by natural disasters and human activities. Here, we provide the first assessment of the genetic diversity and population genetic structures of northwestern Pacific E. chinense. The results analyzed with COI and microsatellites revealed that E. chinense population exhibit metapopulation characteristics, retaining under the influence of the Kuroshio warm currents through expansion of the Late-Middle and Late Pleistocene. We also found four phylogenetic groups, regardless of geographical distributions, which were easily distinguishable by four unidirectional and stepwise adenine-to-guanine transitions in COI (sites 207–282–354–420: A–A–A–A, A–A–G–A, G–A–G–A, and G–G–G–G). Additionally, the four COI hotspots were robustly connected with a high degree of covariance between them. We discuss the role of these covariate guanines which link to form four consecutive G-quadruplexes, and their possible beneficial effects under positive selection pressure.

ENAMEL THICKNESS MEASUREMENTS ON 3D RECONSTRUCTIONS OF TEETH FOR PALEONTOLOGICAL APPLICATIONS

Findings of teeth play a significant role in palaeoanthropology. And excavations in Vietnamese LangTrank cave serve as a vivid example and evidence of this statement. Teeth constitute the majority of the paleontological material dated to Middle and Late Pleistocene periods. This is to some extent the result of dietary preferences of porcupines as these rodents include in their diets bones of animals however avoiding extremely hard coronal parts of teeth. Under such circumstances teeth serve a key to taxonomic differentiation of findings as genetic analysis is often hindered by a lack of preserved DNA at such dating of material. However morphological analysis is difficult in some cases either, as teeth can be worn out or broken. In that case enamel thickness measurements become an effective study instrument as this feature varies between species. In the current study two teeth with clear signs of expressed dental wear, presumably upper fourth premolars of wild boar required more detailed analysis. Thus they were reconstructed after micro-computed tomography scanning similarly to other upper teeth picked for comparison: orang-utan tooth from the same location and two teeth from the Upper Palaeolithic Sunghir (they have been scanned earlier). This study required new approaches to image processing and measurement methodology due to marked attrition of the samples. The workflow and results of enamel thickness assessments which facilitated taxonomical differentiation of the findings are presented in the article.

Preliminary results of a multidisciplinary study of the buried peatland and host sediments of the Moscow-Valdai age (Dmitrov, Moscow region, Russia)

<p>The poster presents preliminary results of multidisciplinary studies of a 5-m section of Middle and Late Pleistocene deposits found in a quarry near the town of Dmitrov, Moscow region. The section includes Moscow fluvioglacial sands, alluvium, lake sapropels, and a layered lens of peat overlain by Valdai cover loams with large cryogenic deformations. The sediments were described and analyzed for pollen, plant macrofossils, and insect remains. The results of pollen analysis suggest that the deposits were formed during the second half of the Mikulino (Eemian) interglacial and during the transition to the Valdai (Weichselian) Glaciation (MIS 5e to MIS 5d). The pollen diagram reflects the replacement of deciduous forests by coniferous forests and the subsequent replacement of closed dark coniferous forests by open communities dominated by birch, shrubs, light-demanding grasses, and <em>Artemisia</em>. Seeds and fruits of wetland and aquatic plants, including endocarps of the extinct species <em>Potamogeton sukaczevii</em>, were found in samples from peat and underlying lake sediments. This may indicate the Mikulino or Early Valdai age of the studied deposits. The entomological fauna indicates the predominance of coastal and marsh species. Environmental conditions were relatively cool, rather characteristic of the late Interglacial. It is expected to obtain micromorphological, physicochemical characteristics of the sediments, as well as OSL dates to clarify the age of the sediments. This work was supported by RFBR, grant N19-29-05024 mk.</p>

Detecting transience in slow evolution landscapes using cosmogenic nuclides and high resolution morphometry

<p>Transient evolution and adjustment to changing tectonic and climatic boundary conditions is an essential attribute of landscapes. We present a new approach to detect and quantify transience in slow erosion landscapes over 100 ka timescales. We compare curvature and cosmogenic nuclides measurements (<sup>10</sup>Be and <sup>26</sup>Al) at hilltop sites with predictions of hillslope diffusion theory, in the slowly evolving quartzitic Serra do Cipó range in SE Brazil, and we observe a distinctive signature of an acceleration of denudation. The timing of this increase cannot be unequivocally associated with a single climatic event but is consistent with climatically-modulated important fluctuations in precipitation and erosion in this area during Middle and Late Pleistocene.</p>