Search

This paper describes a petrified trunk collected from a conglomerate bed of the Springhill Formation (Berriasian-Valanginian) in the Estancia El Álamo locality, Santa Cruz Province, Argentina. The fossil trunk is classified within the ubiquitous genus Agathoxylon and the wood anatomy shows a close affinity to that of Araucariaceae. This Patagonian wood has a distinct combination of anatomical characteristics unique among all known species from the Jurassic and Cretaceous of Western Gondwana allowing to diagnose a new fossil taxon Agathoxylon mendezii sp. nov. Sedimentological and megafloristic proxies of the Springhill Formation suggest that Agathoxylon mendezii sp. nov. grew under a warm and wet climate, which indicates a subtropical to temperate palaeoenvironment. However, the large number of frost rings in the earlywood of this araucarian tree suggests that the palaeoenvironment at Estancia El Álamo was subjected to recurrent disturbances, most likely caused by regional continuous volcanic activity originating from volcanoes located far away to the west. This activity would have produced periodic stratospheric veils that promoted rapid decreases in surface air temperature; the wood response to such stressful conditions would have been the formation of numerous (at least five) frost rings. Although recurrent eruptions in Patagonia during the Early Cretaceous are well recorded, this study is the first to register eruptions recorded in a coniferous wood. [ABSTRACT FROM AUTHOR]

This paper describes a petrified trunk collected from a conglomerate bed of the Springhill Formation (Berriasian-Valanginian) in the Estancia El Álamo locality, Santa Cruz Province, Argentina. The fossil trunk is classified within the ubiquitous genus Agathoxylon and the wood anatomy shows a close affinity to that of Araucariaceae. This Patagonian wood has a distinct combination of anatomical characteristics unique among all known species from the Jurassic and Cretaceous of Western Gondwana allowing to diagnose a new fossil taxon Agathoxylon mendezii sp. nov. Sedimentological and megafloristic proxies of the Springhill Formation suggest that Agathoxylon mendezii sp. nov. grew under a warm and wet climate, which indicates a subtropical to temperate palaeoenvironment. However, the large number of frost rings in the earlywood of this araucarian tree suggests that the palaeoenvironment at Estancia El Álamo was subjected to recurrent disturbances, most likely caused by regional continuous volcanic activity originating from volcanoes located far away to the west. This activity would have produced periodic stratospheric veils that promoted rapid decreases in surface air temperature; the wood response to such stressful conditions would have been the formation of numerous (at least five) frost rings. Although recurrent eruptions in Patagonia during the Early Cretaceous are well recorded, this study is the first to register eruptions recorded in a coniferous wood. [ABSTRACT FROM AUTHOR]

Background and aims: In 2013, blooms similar to those produced by Didymosphenia geminata (Lyngbye) M. Schmidt around the world, were detected in the Grande River basin, Tierra del Fuego province, and in 2014 in de las Vueltas River in Santa Cruz province. The aim of this paper is to analyze the valve morphology and morphometry of these materials to establish if they correspond to D. geminata or to other species of the genus that is producing the massive growth in southern Patagonia. M&M: Samples were collected at Grande River in 2013 and 2015 and, in de las Vueltas River in 2015 and 2016. Samples were analyzed with light and electron microscopy. For morphometric analyses 100 specimens from each sample were measured and statistical analyses were carried out using the R statistical package. Results: The studied populations have the same fine morphology described for other populations collected in Patagonia. Nevertheless, in some sampling sites from Santa Cruz province, we found a morphotype with a markedly smaller size, subcapitated poles, little marked constrictions of the poles, a broad central area (relative to cell size) and 1 to 3 stigmata, that was never reported in South America. Conclusions: The studied populations correspond to D. geminata ssp. geminata Metzeltin & Lange-Bertalot. From a morphological point of view the smaller morphotype present in Santa Cruz belongs to the same subspecies but can be easily misidentified during the routine monitoring programs carried out with light microscope due its size and valve outline. [ABSTRACT FROM AUTHOR]

This paper analyzes plant processing through lithic instruments from a multi-proxy approach for hunter-gatherers contexts of Patagonia. This region presents an archaeobotanical record reflecting the use of diverse species and plant organs, as well as abundant lithic record with evidences of plant processing in different occupational periods. An experimental program combining plant micro-residues studies of two taxa common in the archaeological record with the use-wear analysis of lithic material is proposed here in order to generate functional, technological and methodological interpretations. Cell elements, stains and traces of use are characterized. The program was applied to a sample of different archaeological instruments of the Central plain and the North coast of Santa Cruz province. Micro-residues and use-wear traces identified from these artifacts, together with other contextual information allow us to infer diverse plant processing and manufacture practices. [ABSTRACT FROM AUTHOR]

This paper presents the technological information produced by a regional distributional study conducted within the central sector of the Gallegos and Chico Rivers Interfluve (Pali Aike Volcanic Field, Santa Cruz, Argentina). The goal of this regional survey was to characterize the archaeological signal and its possible latitudinal variations at W70°. By studying the organization of technology and the regional technological structure, we discuss land use strategies and the factors that may have influenced them within this portion of the interfluve. Human use of lagoons is especially targeted. We conclude that hunter-gatherers occupied more intensively those spaces that combine the abundant availability of dark fine-grained rocks of Potrok Aike type with the least distance to river courses. [ABSTRACT FROM AUTHOR]

Well-preserved and diverse Early Cretaceous palynological assemblages were studied from an outcrop section of the Springhill Formation at the Río Correntoso locality (PRC), close to Ghío Lake, in Santa Cruz Province, Patagonia, Argentina. The studied log corresponds to the northernmost outcrops known for the Springhill Formation in the Austral Basin. Most of the palynomorphs algae (Botryococcus, Sphaeroplea, Lecaniella, Zygnema, Pseudoschizaea, Schizosporis, Ovoidites), and some angiosperm pollen grains (Proxapertites , Longapertites, Arecipites) are distinctive and characterize the palaeoenvironment and palaeoclimate of PRC, which was dominated by estuarine coastal margin sedimentites deposited under warm and humid conditions. These angiosperm pollen grains correspond to the earliest record of these group in Patagonia, represented by diverse monosulcates and one rare tricolpate type. This new record of angiosperm pollen in the Springhill Formation provides further evidence that one of the earliest diversifications of angiosperms started at least during the early Cretaceous in Patagonia. Sergio Archangelsky provided an invaluable expertise in the field of paleobotany in multiple ways. His knowledge transcended not only through his papers but also through his exceptional oratory skills. His talks were always enriching in every aspect, combining an engaging historical account with a vision towards the future. "...La paleobotánica un placer, debe ser algo agradable, es decir uno cuando trabaja en paleobotánica le gusta lo que hace, y cuando uno está describiendo, uno se va, y es lo mismo que componer una pieza musical, te perdés, te perdés en todo y lo hacés con gusto, con pasión..." "...The paleobotany is a pleasure, it should be something enjoyable, meaning that when you work in paleobotany, you love what you do. And when you're describing, you get lost, just like composing a musical piece. You lose yourself, in everything, and you do it with pleasure, with passion...". The file with the voice of Sergio Archangelsky is in Supplementary file under Sergio_Archangelsky.mp3. • The palynoflora of the Springhill Formation includes algae and land plants. • Pollen records show features of early members of some taxa (monocots and eudicots). • Angiosperm pollen grains provides evidence for early radiation of some basal taxa in Patagonia. • Palynoflora studied indicates freshwater palaeoenvironment, warm and humid climate. [ABSTRACT FROM AUTHOR]

In this paper, the analysis of a radiocarbon database of the North Coast of Santa Cruz (central Patagonia, Argentina), is presented. Dated archaeological samples were obtained from 56 different types of archaeological sites (open-air -residential sites and burials-, and also rock shelters). The objective of this paper is assessing the continuities and discontinuities in the chronological signal of the area and identifying tendencies along the Holocene. The database currently contains 75 radiocarbon dates falling between ca. 8000 and 300 BP. The radiocarbon data base provides information on the chronological, spatial and contextual variability of the archaeological record of North Coast of Santa Cruz. By means of different analysis of sum of probabilities, we present three different chronological moments of human use of the coast and intermediate zone can be identified. A first moment is represented by early evidence of settlement during Middle Holocene. A second moment corresponds to a hiatus between ca. 5800 and ca. 3900 BP without archaeological evidence. Finally, a third moment is where an increasing of chronological signal occurred, related to greater artifactual variability and an increase in the intensity of human settlement in the Patagonian region. The causes that could have influenced in the discontinuity of the chronological signal of the study area, and the characteristics of the different moments identified are discussed. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to begin to understand human mobility through rock transport at different times in two areas with different environmental characteristics: the Southern Deseado Massif and the basaltic canyons north of the Santa Cruz River. We focus on obsidian, which has a clear geochemical signature and an uneven distribution. Additionally, we use macroscopic information on siliceous rocks, which at present have only been identified in northern areas, although they may also be recovered randomly and in low frequencies in southern ones. During the initial peopling of the Southern Deseado Massif (ca. 10,800 BP), inhabitants were transporting black obsidian as well as translucent chalcedony, probably as part of the individual gear. During the Late Holocene, the number of obsidian artifacts decreased in the Southern Deseado Massif, related to a better knowledge of the high-quality local lithic resources and/or to the existence of higher population densities. Obsidian artifacts are more abundant in the northern Santa Cruz River basin than in the southern Deseado Massif, suggesting the existence of a relationship with areas located to the northwest, close to the obsidian source, as other lines of evidence suggest. In addition, the presence in the basaltic canyons of artifacts made from high-quality siliceous rocks, more abundant and predictable in northern areas, could also be the result of human movements following a north-south direction. [ABSTRACT FROM AUTHOR]

Lithic resources at the Central Plateau of Santa Cruz (Argentina) are abundant, ubiquitous and of very good quality for knapping. They have been exploited by hunter–gatherer societies since the latest Pleistocene until the Late Holocene. The study of their distribution, availability, and ways of exploitation at the quarries, together with the information stemming from the archaeological sites, enable the understanding of the first stages of tool production and consumption. In this paper, two quarries from La María Archaeological Locality (Cantera de Sílex de CDM and Cantera Bosque Petrificado) are studied and compared. Their geomorphologic location is described. The lithological characteristics of the outcrops, the size of the stones, and the variability of raw materials available at them are also addressed. The accessibility and visibility of the quarries are analyzed. The way raw materials were exploited at the sources is evaluated taking into consideration their relationship with the local and regional structure of lithic resources. The information generated for the quarries is complemented and compared with the local trends identified for the habitation sites. This enabled the formulation of a general model about the first stages of production. Although the quarries have different types of raw materials (flint and silicified wood), results show that similar technological strategies were implemented in them. These are in agreement with the general trend at the local and regional levels. Both sources are easily accessible from the surrounding landscape. They are visible from nearby areas. Probably, they were exploited mainly from nearby sites. At the quarries, the first stages of tool production were performed: core decortication and preparation and the production of blanks. The acquisition of raw material involved the selection of good quality nodules and boulders and the production of polyhedral cores knapped in multiple directions. These cores could be transported to the habitation sites or could be discarded in situ while still presenting active platforms. On the other hand, differences in some procurement practices might be related to decisions and variations linked to the particular characteristics of the resources in both outcrops. [ABSTRACT FROM AUTHOR]

The aim of this paper is to generate new data on raw material sourcing of multiple activities sites at La Primavera locality to describe some provisioning strategies adopted by mobile hunter–gatherer societies, and contribute to the study of the local settlement in the wider regional context. The local structure of lithic resources is characterized; the natural distribution of useful rocks is modeled and the raw materials of artifacts from multiple activities sites are sourced. The classification and sourcing technique applied is not a determinant method, but a preliminary approach adequate to deal with a very large lithic artifact sample. The rock distribution across the landscape was analyzed using a Geographical Information Systems (GIS) for compiling the available data and estimating the distances from the sites to the sources for each raw material found in them. Based on the circulation distances and different considerations regarding the characteristic of the lithic sources, three different provisioning strategies are delineated. They suggest that settlement at the locality involved a certain permanence time that surpasses a logistic use, while keeping trade and social networks with other localities in the regional context. [ABSTRACT FROM AUTHOR]

This paper discusses provisioning strategies of lithic raw materials at Maripe Cave site (province of Santa Cruz, Argentina). The archaeological sequence represents different moments of human occupation at the cave and in the study area, which show different lithic technologies. The morpho-typological analysis of the lithic cores recovered contributes to our knowledge about the strategies related to procurement and provisioning of the lithic raw materials used for artifacts production. We identified different raw materials from the analyses of lithic cores and other artifacts from the site. This allowed analyzing trends in selection and provisioning processes and interpreting the mobility strategies of the groups that inhabited the Deseado Massif since the Pleistocene–Holocene transition. Trends suggest that, during the Pleistocene–Holocene transition and early Holocene, abandoned cores from Maripe Cave mainly indicate people provisioning strategies. During middle Holocene, the cores shows blades extractions and raw material use from long distance, discarded with remaining potential utility. Finally, at late Holocene the cores were mainly prepared for blade extractions. Our results do not fully agree with Kuhn's proposal, probably due to both the theoretical polarization between the provisioning strategies and the palimpsest effect. [ABSTRACT FROM AUTHOR]

The upper member of the Río Turbio Formation is a well-exposed marine Eocene unit at high latitudes in Patagonia, Argentina. It holds important information helpful to reconstruct regional climate and oceanographic patterns in an area adjacent to the Drake Passage. Knowledge on the paleoenvironmental and paleoceanographic evolution of the southwestern Atlantic Ocean during the Paleogene is hindered by the lack of precise tools to date and correlate the sedimentary units. In this paper we present the dinoflagellate cyst assemblages from the upper member of the Río Turbio Formation and compare the stratigraphic distribution of their species with the ranges proposed in the Paleogene Southern Pacific Ocean dinoflagellate cyst zonation. The abundance of Enneadocysta dictyostila , the first occurrence of Impagidinium parvireticulatum and the presence of Vozzhennikovia apertura all allow us to propose a mid-Lutetian to mid-Priabonian age (44.6 to 34 Ma) for the upper member of the Río Turbio Formation. The study section is characterized by a middle Eocene endemic-Antarctic dinocyst assemblage. According to the dinocyst assemblages the analyzed section can be divided into four zones. Zone I is dominated by E. dictyostila , which points to a distal setting in an inner shelf environment. Zone II exhibits a high abundance of V. apertura , thus suggesting high trophic levels and cool waters in a shallow-marine, coastal environment. Zone III is dominated by I. parvireticulatum and a lower abundance of E. dictyostila , both species indicating a possible deepening of the depositional area with increasing influence of oceanic waters. Finally, Zone IV is dominated by V. apertura , indicating shallow marine waters. Our data suggest that V. apertura could have been produced by a stress-tolerant dinoflagellate species. Toward the top of the section, the samples are dominated exclusively by sporomorphs and zygospores of fresh-water green algae, which indicate a transition from a tide-dominated deltaic to a continental environment. [ABSTRACT FROM AUTHOR]