 Subjects -> PALEONTOLOGY (Total: 43 journals)
|
|
|
- Revisiting Battistini: Pleistocene Coastal Evolution of Southwestern
Madagascar
Abstract: The study of paleo shorelines, particularly of those formed during the late Quaternary, provides robust insights into past climate variability. Advances in surveying techniques and chronological methodologies have dramatically improved the inter-comparability of regional and basin-wide paleo shoreline surveys. However, these advances have been applied unevenly across the globe. This is especially true in southwestern Madagascar, where, in the 1960s and 1970s, emerged Pleistocene beach and reef facies were first described in detail and dated to Marine Isotope Stage (MIS) 5a using U–Th alpha activity counting by french geologist René Battistini. Now, 50 years on, no further analysis of the coastal sequence has been made. In this study, we present an updated late Pleistocene coastal evolution model for the southwestern Madagascar coast. Utilizing a combination of Structure-from-Motion/Multi-View Stereo techniques and differential Global Navigation Satellite System surveys, we have created five high-resolution 3D outcrop reconstructions that have, in turn, been chronologically constrained using 10 U-series ages from both in situ and reworked coral samples. Our data suggest that the emerged reef was deposited during MIS 5e (∼125 ka), then was covered by intertidal and beach sediment (including redeposited coral clasts of MIS 5e age), and finally capped off by thick eolianites. This sequence would suggest that the local sea level must have remained stable throughout MIS 5e in order to allow for the progradation of both the beach and reef environments. Published on 2022-12-27 10:20:56
- Investigating Past Livestock Mobility Using δ34S Stable Isotopes:
Three Preliminary Case Studies From Prehistoric Croatia
Abstract: The benefit of including sulfur (δ34S) stable isotopes in studies of past human diet and migration is increasingly clear, but δ34S analyses remain underutilized in addressing other patterns of mobility, animal management, and environmental change in the archaeological record. Here we evaluate the ability of δ34S isotope values to act as proxies for prehistoric environments in three distinct regions of Croatia: northern Dalmatia, Lika, and central Croatia. We then assess if δ34S isotope values can highlight differences in herding and management practices of livestock in these areas, specifically those that encourage the movement of herds into various parts of the landscape (e.g., transhumance vs. localized grazing). Analysis of faunal stable isotope values from these geographically diverse sites constitute the first step in building an environmental database for Croatia and addressing questions of how δ34S can be applied to questions about animal husbandry in the archaeological record. Published on 2022-11-30 10:36:32
- Cartesian Coordinates in Two-Dimensional Bone Histology Images for
Quaternary Bone Remodelling Research
Abstract: Palaeohistologists who work with well-preserved cortical bone can examine two-dimensional (2D) histology images for quantitative parameters of secondary osteons and Haversian canals to reconstruct past bone remodelling. Standard techniques in this space include area measurements and counts of histology components recorded from an image. The ‘point-count’ technique involves counting all the items (e.g., secondary osteons, osteocyte lacunae) of interest per image area. The open access image analysis software ImageJ/FIJI facilitates this technique in a user-friendly way. Raw data points are captured and can be saved in a spreadsheet. Aside from the total number of counts, the software also issues Cartesian (XY) coordinates locating each counted point. These XY coordinates are typically neglected within palaeohistological approaches due their assumed irrelevance to research questions of bone remodelling significance. We provide a short evaluation of XY coordinates captured by ImageJ/FIJI from 2D bone histology images, and a protocol for a simple calculation of XY distances that follow the path of point counting. We focus on osteocyte lacunae which serve as a proxy for osteoblast-osteocyte conversion in live bone by replicating the protocol on a bone sample from a human Medieval English individual. We discuss the potential of XY coordinates for reconstructing the proximity of osteocyte lacunae and related bone remodelling activity through exchange of nutrients by neighbouring cells. We recommend palaeohistologists report XY coordinate data in their results to ensure better vertebrate palaeobiology characterisation. Published on 2022-09-07 12:09:04
- From 20,000 Years Ago to Near Present Climate Classification of North
America
Abstract: Climate classification allows an efficient encapsulation of climate data into climate units. For North America and most of Central America during 20, 14, 13, 11, 10, 7, 5, and 1 thousand years ago (ka) and recent years, I applied a Köppen-Trewartha classification system, but with dry classes subsumed under primary thermal classes to preserve information. The boreal and polar classes decreased from a combined 70% of area during 20 ka until reaching 42% of area at 7 ka, after which the area remained relatively stable. Conversely, the subtropical and temperate classes increased from 25% of area until reaching 53% of area at 7 ka, with slight increase of the tropical class. The combined dry subclasses increased from 7.5% to 15% of area, primarily in the subtropical and temperate classes, displaying unique trends over time. Based on ordination, the classes since 5 ka are similar; the 1950 interval is most similar to 1 and 5 ka and the intervals of 1600 and 1800 are most similar. The climate classes and transitions generally corresponded with major vegetation distributions. Visually, political boundaries appeared to parallel climate classes, which might indicate the influence of long-standing ecological differences on human land use and settlement. A future research need is identifying the influence of climate on directing settlement and political boundary establishment. Published on 2022-08-03 11:10:51
- Orbital, the Box – an Interactive Educational Tool for In-depth
Understanding of Astronomical Climate Forcing
Abstract: “Orbital, the Box” provides an interactive tool with graphical user interface (GUI) for stimulating active, visual learning for understanding of astronomical climate forcing. This cross-platform tool can be run locally on a personal computer using a standard web browser environment with no need for plugins, thus maximising accessibility for students and teachers alike. The tool facilitates in the development of a holistic and quantitative understanding of astronomical climate forcing by allowing students to independently vary orbital parameters, after which they can instantaneously see the resulting effect upon the seasonal and latitudinal distribution of solar irradiance arriving at the top of the Earth’s atmosphere. Such an approach follows a classic controlled experimental design whereby one parameter can be changed while all others are kept constant. This experimental tool can be deployed as a virtual laboratory, including within a flipped classroom setting, to promote active learning of traditionally challenging concepts such as the roles of eccentricity and precession in astronomical climate forcing, and in particular their interaction with Kepler’s second law and the subsequent consequences for season length. Published on 2022-08-03 11:03:22
- A Simplified Palaeoceanography Archiving System (PARIS) and GUI for
Storage and Visualisation of Marine Sediment Core Proxy Data vs Age and
Depth
Abstract: Scientific discovery can be aided when data are shared following the principles of findability, accessibility, interoperability, reusability (FAIR) data (Wilkinson et al., 2016). Recent discussions in the palaeoclimate literature have focussed on defining the ideal database format for storing data and associated metadata. Here, we highlight an often overlooked primary process in widespread adoption of FAIR data, namely the systematic creation of machine readable data at source (i.e. at the field and laboratory level). We detail a file naming and structuring method that was used at LSCE to store data in text file format in a way that is machine-readable, and also human-friendly to persons of all levels of computer proficiency, thus encouraging the adoption of a machine-readable ethos at the very start of a project. Thanks to the relative simplicity of downcore palaeoclimate data, we demonstrate the power of this simple but powerful file format to function as a basic database in itself: we provide a Matlab-based GUI tool that allows users to search and visualise isotope data by sediment core location and species type, against either depth or age. We share the database format here so that other laboratories might consider developing a similar approach depending on their own needs and requirements. Published on 2022-05-20 13:39:22
- Osteometric Study of Metapodial Bones and Phalanges as Indicators of the
Behavioural Ecology of Modern Reindeer (Rangifer tarandus) and
Implications for Reconstruction of Paleo Mobility
Abstract: Paleolithic reindeer (Rangifer tarandus) played an important role for human populations in western and central Europe during much of the Paleolithic period. In southwestern France and in particular during the Magdalenian, reindeer frequently figures among the privileged prey of hunter-gatherer groups. However, and despite numerous attempts to reconstruct the migratory behavior of Paleolithic reindeer, there is no agreement on the degree of mobility of this prey. Modern ethological data indicate that reindeer herds adopt different mobility strategies depending on the type of habitat and the topography of the environment. Thus, our project (Emorph) aims to explore morphometric criteria (through metapodial bones and phalanges) in combination with cutting-edge methodologies like Machine Learning to identify the extent of reindeer migrations. Based initially on the study of modern caribou populations with distinct migratory behaviors, the results obtained could be applied to several Magdalenian assemblages from southwestern France in the future, with the goal of reconstructing the mobility of these tardiglacial reindeer. Published on 2022-05-09 12:15:41
- Polar Bear Fossil and Archaeological Records from the Pleistocene and
Holocene in Relation to Sea Ice Extent and Open Water Polynyas
Abstract: The polar bear (Ursus maritimus) is the apex predator of the Arctic but its distribution throughout the Pleistocene and Holocene has not previously been reported. Although natural death specimens of this species (‘fossils’) are rare, archaeological remains are much more common. This historical compilation presents the record of known ancient polar bear remains from fossil and archaeological contexts before AD 1910. Most remains date within the Holocene and derive from human habitation sites within the modern range of the species, with extralimital specimens documented in the north Atlantic during the late Pleistocene and in the southern Bering Sea during the middle Holocene reflecting natural expansions of sea ice during known cold periods. The single largest polar bear assemblage was recovered from an archaeological site on Zhokhov Island, Russia, occupied ca. 8,250–7,800 a BP during the warmer-than-today Holocene Climatic Optimum: 5,915 polar bear bones were recovered, representing 28% of all remains identified. Polar bear fossils and archaeological remains across the Arctic are most often found in proximity to areas where polynyas (recurring areas of thin ice or open water) are known today and which likely occurred in the past, including for the oldest known fossil from Svalbard (ca. 130–115 k a BP) and the oldest known archaeological specimens from Zhokhov Island (ca. 8,000 a BP). This pattern indicates that as they do today, polar bears may have been most commonly found near polynyas throughout their known historical past because of their need for ice-edge habitats at which to hunt seals. Published on 2022-05-06 12:16:59
- Evidence for Marine Consumption During the Upper Palaeolithic at “El
Pirulejo” Inland Rock- Shelter (Southern Iberia Peninsula, Spain)
Abstract: During the Last Glacial Maximum and deglaciation, the Iberian Peninsula served as a faunal and human population refugium. Human foodways have always played a pivotal role in understanding social and cultural practices in prehistory. Nonetheless, the limited number of archaeological sites and human remains in this region hinders the complete understanding of these critical communities’ diet.To increase our knowledge about human consumption patterns, we selected three Magdalenian levels from the site of El Pirulejo (Southern Iberia Peninsula, Spain). These levels are characterized by a high abundance of rabbit (Oryctolagus cuniculus) remains (76–97% MNI), initially suggesting that rabbits were the primary source of protein for site inhabitants. Stable isotope analysis was conducted on two human teeth in tandem with stable isotope analysis of the rabbit teeth. Contrary to the expectations derived from the zooarchaeological analysis, rabbits were not a significant source of dietary protein. Carbon and nitrogen bulk isotopic values are the most enriched found in sampled human remains for this area and context.Our data supports aquatic food resource inclusion and increased resource diversity among Iberian hunter-gatherers during the Magdalenian. This study is consistent with previous studies that suggested a socio-economic network among human groups between inland and coastal regions in the terminal Pleistocene Southern Iberia. Published on 2022-05-05 13:19:01
- Sedge Foodplants Growing in the Cradle of Humankind, South Africa, and
Cyperus Esculentus Tubers (Patrysuintjies) as a C4 Superfood
Abstract: Since it was established that the early hominins of the Cradle of Humankind in South Africa ate 13C-enriched foods that may have included sedges with C4 photosynthetic pathways, much work has focused on the reconstruction of hominin dietary ecologies in both southern and eastern Africa. Through the years emphasis was placed on Cyperus papyrus as a possible source, even inspiring an ‘aquatic diet’ hypothesis for all hominins. Baboon feeding habits and sedge regimes observed in South Africa’s ‘Lowveld’ have provided a proxy for the dietary ecology of the southern ‘Highveld’ hominins, and from the Cradle of Humankind sedges, amongst other plants, have been collected for nutritional studies. To date, however, there has been no attempt to compile an inventory of the sedge species currently growing in the demarcated area of the Cradle of Humankind. Here I list 29 Cyperaceae taxa currently recorded as growing in the Cradle of Humankind. I show that, contrary to previous inference, most of them have C4 photosynthetic pathways and do not need aquatic ecologies or permanent wetland settings. I discuss and provide photographic records for the six species identified as current baboon and human foodplants, and highlight Cyperus esculentus as a possible nutritious and prolific C4-sedge-USO food source for southern African hominins based on its energy, protein and fat/lipid profile. Published on 2022-04-18 10:42:08
|
Open Access journal
