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Despite being generally remembered for its forest formations; South America is the continent with the most grassland ecosystems. Among these grasslands, the Pampa stands out, occupying areas in Argentina, Brazil, and Uruguay. This biome presents a wide variety of vegetation formations, among which one is notable for its ecological and cultural importance – the Butia palm groves, a grassland with a marked presence of palms from the genus Butia. To help understand the evolution of the Butia palm groves, this study delves into the intricate relationships among climatic variations, sea-level changes, anthropogenic influences, and vegetation dynamics in the Pampa, the stage where these palm groves have developed. Through a literature review it was possible to stablish a climatic evolution of the area where the Pampa occurs. The Last Glacial Maximum had colder temperatures and drier conditions leading to the expansion of grassland-type vegetation. The Pleistocene-Holocene transition witnessed a gradual warming, initiating a shift from grasslands to forest taxa, though regional variations persisted. The Early Holocene saw diverse climatic patterns, ranging from humid environments to semi-arid climates in different Pampa regions. Entering the Middle Holocene, warming trends prevailed, influencing vegetation dynamics. Anthropogenic influences and the Holocene Transgression became pivotal factors, with evidence of increased fires and sea-level-induced changes along the coastal region. The Late Holocene marked a regression, leading to desalinization, and a general expansion of forest taxa. This study also presents an introduction to the relationship between the first human inhabitants of the Pampa and the Butia palms. This comprehensive exploration elucidates the intricate connections between climatic shifts, sea-level changes, vegetation dynamics, and human-environment interactions, underscoring the importance of considering historical contexts in understanding contemporary ecosystems. • The Pampa harbors rich biodiversity, comparable to tropical forests. • Butia palm grove, an ecosystem found in the Pampa, is essential for biodiversity conservation. • Examining climatic and environmental evolution since the LGM helps understand Pampa and Butia palm grove biodiversity. • Indigenous peoples have had longstanding ethnoecological relationships with the Butia palm. • Understanding historical human- Butia interactions is key for a broad view of the Pampa's socioecological dynamics [ABSTRACT FROM AUTHOR]

During the transition from the Pleistocene to the Holocene, significant changes occurred on the Brazilian continental shelf. In this study, we investigated the environmental changes that occurred during this period through the quantification and classification of cosmopolitan dinoflagellate cysts. We used three cores collected in the northern part of the Santos Basin and analyzed a total of 42 samples. The results showed a predominance of cysts of O. centrocarpum, L. machaerophorum and T. vancampoae, whose occurrence was influenced by sea-level fluctuations during the Pleistocene-Holocene transition and by changes in ocean currents due to temperature variations. Oligotrophic species were established during the Late Pleistocene, followed by mixotrophic species from the Holocene. Analysis of the dinocysts showed the presence of colder waters due to upwelling and the entry of waters with lower salinity due to the formation of transitional estuarine systems. These environmental changes have contributed to the configuration of the current Brazilian coastal scenario. • Study of dinoflagellates cysts in sediments of Brazilian shelf. • Changes in dinoflagellate assemblages on the shelf during the LGM and later periods. • Sea-level transition from Last Glacial Maximum (LGM) to Holocene. • Climatic variations. [ABSTRACT FROM AUTHOR]

Only a few studies on Quaternary continental mollusks of Uruguay have been published over the last few decades. Despite the high occurrence of this group in many of the Late Pleistocene outcrops of the country, all of them are better known for their classic Ice Age mammal assemblages. To overcome this situation, 23 localities were sampled from two lithostratigraphic units: the Sopas and Dolores formations. The identified species are included in the families Sphaeriidae, Cyprinidae, Mycetopoda, Acridae (freshwater bivalves); Ampullariidae, Cochliopidae, Tateidae, Chilina, Physidae, Planorbidae (freshwater gastropods); Scolodontidae, Succineidae, Charopidae and Bulimia (terrestrial gastropods). As a result of these new samplings, the Sopas Formation mollusk species count increased from 20 to 29 species, and the Dolores Formation from six to 29 species. Seventeen of these species are new records for the Quaternary of Uruguay , and eight for the Quaternary of South America. Two bivalves, five freshwater gastropods, and a new terrestrial gastropod were added for the Sopas Formation; and for the Dolores Formation, four new bivalves, 14 new freshwater gastropods, and five new terrestrial gastropods. The Dolores Formation has been the most understudied unit until now, increasing here its biodiversity to 23 species. These new records of freshwater and terrestrial gastropods, increase the biodiversity and biogeographical range of the continental mollusks of the Late Pleistocene-early Holocene of the region. In addition, new AMS 14C ages were obtained for both lithostratigraphic units, framing the age of the mollusk assemblages for both formations in the a maximum range of 13,000–48,000 years before the present. • This paper is a comprehensive study of the continental mollusks species composition of two Quaternary stratigraphic units from Uruguay. • In this work, 17 new species of freshwater and terrestrial mollusks are described for the first time for the Late Pleistocene of Uruguay. Of those species, nine are new for the Quaternary of South America. • Comparing with the Pampean Region, the assemblages of Uruguay can be related with the Quaternary Assemblages from Pampean Argentina and Rio Grande do Sul (Brazil). [ABSTRACT FROM AUTHOR]

Very few excavated sequences in southern South America provide an approximation to the environmental evolution covering the segment Late Pleistocene-Holocene. Here we present the taphonomic analysis and paleoenvironmental reconstruction based on the small mammal remains retrieved from the archaeological and paleontological site Gruta del Indio (Mendoza Province, Argentina). Radiocarbon dates situate the small mammal deposits studied within the Late Pleistocene and Holocene. Thus, these assemblages provide a record for inferring environmental evolution in the middle basin of Atuel River during the last ∼31 ky BP. Taphonomic analysis revealed that most of small mammal remains were incorporated by a little destructive nocturnal owl. Recorded species include mainly cricetid and caviomorph rodents and a single marsupial. While Pleistocene assemblages have not exclusive species, the specific richness increases towards the Holocene probably linked with the climatic variability related to ENSO. In overall, the recorded small mammals suggest environmental stability during the Late Pleistocene-Holocene, mostly associated with Monte Desert conditions. Conversely, the pollen sequence studied from Gruta del Indio was interpreted as indicator of a deep environmental change during the Pleistocene-Holocene transition, when the Patagonian steppe was replaced by Monte Desert. Potential biases linked with these kinds of proxies are discussed. [ABSTRACT FROM AUTHOR]

This work presents data on charcoal fragments found in Cenozoic deposits of the Boa Vista Formation and the first absolute dating for this unit. The methodology consisted of the definition of sedimentary facies, as well as the establishment of depositional age using optically stimulated luminescence (OSL) in quartz grains. Analysis was carried on charcoal samples with the help of Scanning Electron Microscopy (SEM), AMS 14C dating, and organic petrography. The facies analysis identified four distinct facies: lateritic massive gravel facies (Gcm1), ferruginous massive gravel facies (Gcm2), massive sand facies (Sm) and fossiliferous massive sand (Smf). The ages of the deposits ranged between 105,2 and 3,2 thousand years before present, indicating that this unit is positioned in the Upper Pleistocene-Upper Holocene transition. The anatomical structures observed in SEM are well preserved and the studied charcoal samples have angiospermic affinity. Two episodes of fires were identified with range ages between 5663 and 3377 cal years BP, with burning temperature varying from 340 °C to 400 °C. • OSL dating for the Cenozoic portion recorded a Pleistocene - Holocene age. • Fire episodes have been identified for the Middle Holocene of northwestern Brazil. • These fire episodes corroborate data recorded for other regions of the Amazon. [ABSTRACT FROM AUTHOR]

Here we describe the left mandibular ramus of a fossil peccary from the submerged karst cave system in the southeastern Mexican state of Quintana Roo. The specimen, which was discovered in the Muknal cave northwest of Tulúm, is a new genus and species of peccary termed Muknalia minima. The taxon likely dates from the latest Pleistocene and differs significantly from all extant peccaries and their Pleistocene relatives by a concave notch at the caudal edge of the mandibular ramus and prominent ventrally directed angular process. These diagnostic osteological differences suggest that the masticatory apparatus differed from all other peccaries, which may hint to an ecological isolation on the late Pleistocene Yucatán Peninsula. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to analyze the morphology of the Quaternary relict features and bedforms that characterize the outer zone of an extensive mesomareal system, which is part of the Bahía Blanca estuary (Argentina), and to estimate the prevailing hydro-sedimentological conditions on the continental shelf adjacent to the estuary. Surveys with a multibeam bathymetric system, side-scan sonar and a high-resolution seismic system (3.5 kHz) were carried out and bottom sediment samples were collected. In general, the seafloor presents a varied configuration, marked by changes in its physiography. The Quaternary relict features are composed of two terraces (12–14 m and 18–22 m deep), with steeply sloping escarpments, that are oriented approximately parallel to the current coastline. Associated with these terraces, wide abrasion platforms develop with irregular and plateau-like structures up to 4 m high, together with large rocky blocks up to 6 m in diameter. Here, the predominant sediment corresponds to a gravel-sized material composed of quartzite boulders, siltstone fragments of up to 7 cm, and biogenic remains with different degrees of fragmentation. These sedimentological data, together with the bathymetric and seismostratigraphic information, indicate that the terraces and abrasion platforms are ancient shorelines that originated in an environment with high wave energy, corresponding to periods of stabilization of sea level rise during the final stage of the last postglacial transgression (late Pleistocene-Early Holocene). On the other hand, asymmetric dunes of different sizes (0.5 m < height < 5 m, 5 m < wavelength < 200 m), sand ribbons (length > 300 m) and comet marks originated in equilibrium with the present-day hydro-sedimentological conditions. The availability of sandy material mobilized as bedload is the determining factor for the generation of the varied bedforms. Thus, sand ribbons and comet marks are generated especially in the northern sector of the area, with mobile sediment thicknesses ≤ 0.5 m. With larger thicknesses the formation of dunes occurs. Their size and asymmetry show an intense transport of sand as bedload towards the continental shelf, the southern sector of the area being the main route of the sediment that leaves the estuary. This sediment is the supply source of the sandy shoals that are part of the great ebb delta developed on the continental shelf in the external area of the Bahía Blanca estuary. • Quaternary relict features coexist with current bedforms. • Terraces and abrasion platforms associated with ancient coastlines are recognized. • Transition between comet marks, sand ribbons and dunes is evident. • The sediment availability determines the generation of different types of bedforms. [ABSTRACT FROM AUTHOR]

Palaeoecological reconstructions document past vegetation distribution with estimates of the communities boundaries shifts. This work presents a compilation of palaeoecological studies from southern Patagonia Argentina as a contribution to a better understanding of the composition and distribution of Andean and extra-Andean plant communities. Paleoenvironmental reconstructions are based on pollen sequences from different types of deposits located in the forest, forest-steppe ecotone and steppes between 46° and 51°S. The comprehension of modern pollen and its relation with the actual vegetation is a critical component of palaeoecological research. Models of the current relationship pollen-vegetation-climate were applied to interpret these sequences. Their integration made it possible to reconstruct the spatio-temporal patterns of vegetation and past climatic changes since the Late Glacial-Holocene transition. Four areas were selected to map past vegetation communities; three lake basins: Pueyrredón, San Martín and Argentino, and the Deseado Massif. The local conditions given by the geomorphology of each site were also taken into account. The vegetation reconstruction during the Pleistocene-Holocene transition came from records located in the Deseado Massif only, and indicated steppes, without modern analogues, linked to arid and cold conditions. During the Holocene, plant communities were sensitive to moisture conditions related to westerly winds or Atlantic-derived precipitation events. Taxa related to the anthropogenic impact of the past centuries were found at all sites, both in Andean and extra-Andean Patagonia. • Compilation of palaeoecological studies from southern Patagonia, Argentina. • Paleoenvironmental reconstructions based on pollen sequences from different deposits. • Plant communities were sensitive to westerly winds or precipitation from the Atlantic. [ABSTRACT FROM AUTHOR]

A review of relative sea-level (RSL) oscillations during the Holocene in Rio de Janeiro, southeastern Brazil, is presented based on new data. This new data encompasses analytical techniques, altimetric corrections and age recalibrations, using the marine local radiocarbon reservoir correction of 96 ± 48 yrs. The effectiveness of geological and biological RSL indicators was tested, aiming to provide consistent information for future researches on the east coast of South America. Results confirm that RSL during Late Pleistocene - Holocene transition (11,970–11,122 cal yrs BP) was 4.5 m below Mean Sea-level (MSL). After that transition, a relatively rapid rise began. At approximately 7948–7598 cal yrs BP, the MSL was 0.5 m below the current marine level. Present-day, "zero", was reached for the first time in the Holocene, at approximately 7686–7269 cal yrs BP. The maximum level of the Holocene marine transgression occurred around 4787 - 4104 cal yrs BP with a height of 3.0 m above MSL. At the point of maximum transgression, the sea-level began a general behavior of lowering. However, between 3981 and 3345 to 1852 - 1413 cal yrs BP, evidence from vermetids suggests several alternating periods of slow and rapid sea-level, identified by four oscillations. New records, between 1220 - 780 and 1055 - 665 cal yrs BP, have indicated a continue lowering trend of RSL. • Data on changes in the relative sea level along the coast of Rio de Janeiro, southeastern Brazil, were reviewed and reassessed. • Geological and biological indicators of high vertical resolution for RSL curve were selected. • The chronological data were corrected by the marine local radiocarbon reservoir correction, offset ΔR = 96 ± 48 yrs of 14C. • An RSL curve for the last 11500 cal yrs BP for the state of Rio de Janeiro, southeastern Brazil was elaborated. [ABSTRACT FROM AUTHOR]

During the Pleistocene, a diverse fauna composed of large and mega mammals lived in the Northeastern of Brazil, and is generally associated with open environments. We present in this study carbon and oxygen isotopic data of Notiomastodon platensis and Toxodontinae from the fossiliferous deposit of Lajedão do Patrício, João Dourado, Bahia, Brazil. The analyzes of δ 13C and δ 18O were carried out to better understand the paleoecology of these taxa and, consequently, make it possible to obtain paleoclimatic and paleoenvironmental inferences about the region of Lajedão do Patrício fossiliferous deposit. The δ 13C values identified for Notiomastodon platensis (−5.67‰ and −6.95‰) and Toxodontinae (−5.62‰ and −7.03‰) indicate a mixed diet for these taxa due to the consumption of C 3 and C 4 plants, indicating an environmental scenario of vegetation mosaic of dry forest (caatinga) and cerrado during the Pleistocene/Holocene. The comparison between the δ 13C data from the megafauna in Northeast Brazil allowed the identification of opportunistic behaviors for Notiomastodon platensis and Toxodontinae, varying between the browser, mixed and grazing habits, according to the characteristics of the habitat in which they lived. The δ 18O data and its variations suggest changes in the precipitation regime during the Pleistocene/Holocene transition in the region of the analyzed fossiliferous deposit. • Analysis of stable isotopes (carbon and oxygen) in fossil teeth of the Quaternary megafauna in northeastern Brazil. • Paleoenvironmental scenario of vegetation mosaic with dry forest and grass vegetation. • Comparison of date isotopic and paleoclimatic curves indicates different climatic and environmental conditions. [ABSTRACT FROM AUTHOR]

The Preto River, located in the municipality of São Gonçalo do Rio Preto (Minas Gerais, Brazil), is one of the few perennial watercourses in the semi-arid region of northeastern Minas Gerais and is essential for the socio-environmental dynamics of the region. Its headwaters are located in the Southern Espinhaço Mountain Range, which is characterized by predominantly quartzite lithologies that form a relief with dissected altimetric variations interspersed with planation surfaces, where the climate is high-altitude tropical. The soils are poorly developed and small fragments of forest, together with phytophysiognomies of the Cerrado Biome such as wet grasslands (Campo limpo úmido), colonize the peatland ecosystems. The aim of this study is to contribute to the paleoenvironmental reconstruction of the headwaters of the River Preto, using sliliceous bioindicators associated with other indicators (multi-proxy analysis). It was possible to infer that there was no change in phytophysiognomies from around 23,330 cal years BP to the present. However, there were 4 periods with oscillations between a cooler, drier environment in the Late Pleistocene, which gradually became warmer and more humid in the Late Holocene. Period 1 (Late Pleistocene) corresponds to the interval from before 23,300 to 13,500 cal years BP, in which the low tree density index (D/P) indicates vegetation similar to the current. Period 2 (end of the Late Pleistocene) corresponds to the period between 13,500 and 11,700 cal years BP. The increase in the D/P index indicates a small expansion of tree vegetation, albeit with the continued predominance of open vegetation. The appearance of Arecaceae characteristic phytoliths, associated with the drop in the climate index (Ic%), indicates an increase in temperature in relation to the previous phase. Period 3 (Pleistocene to Holocene transition) corresponds to the period from 11,700 to 10,000 cal years BP. It is a little colder and drier than the previous period, as observed from the increase in the climate index (Ic%). This period includes the Younger Dryas event, which was colder and drier than currently and had a global influence. Period 4 (Holocene) corresponds to the last 10,000 cal years BP. During this period there was no change in vegetation cover, the D/P and Pa/P indexes remain low, and there is a tendency towards a gradual increase in temperature. The use of siliceous bioindicators associated with other proxies and the regional and global events that occurred during the Quaternary in the analyzed sediments enabled the observation that, at least in the last 23,300 cal years BP, there have been no changes in the local vegetation cover. However, there were small expansion episodes or decreases in the density of tree and Arecaceae cover, as well as a tendency towards increased temperature and humidity in the Upper Holocene. The results proved to be useful for paleoenvironmental research and highlighted how peatland ecosystems are fundamental for understanding the evolution of the landscape and for reconstructing the environmental history of the Cerrado biome. • The headwaters region of Rio Preto, in Minas Gerais state, Brazil, was studied. • For biomineralization analysis, 21 samples were selected in a core from peatland. • Grasses predominate, indicating open vegetation (grassland phytophysiognomy). • The region become warmer and more humid in the Holocene. • Events of expansion or retraction in the density of tree cover have been identified. [ABSTRACT FROM AUTHOR]

The tragic fire at the National Museum (Brazil) in September 2018 caused invaluable losses to South American natural and cultural heritage. However, previous visits to the paleontological collection generated photographic and descriptive records of mammalian fossil specimens from the Pleistocene of Brazil. Thus, it was possible to redescribe and revise the taxonomy of Cervidae fossils from two important paleontological sites in the Brazilian Intertropical Region (João Cativo and Lage Grande). These fossils include antlers and lower teeth, and they were described and taxonomically identified by morphological comparisons with all extant and extinct South American deers. A new diversity of Cervidae was recognized, differently from that proposed in the literature, which recognized the presence of Hippocamelus sulcatus , Mazama americana , and Ozotoceros bezoarticus. Instead, the Cervidae fossils from João Cativo and Lage Grande sites belong to the extinct deer Morenelaphus. Although some specimens could not be identified at a specific level (Cervidae indet.), a comparative analysis of the estimated body mass pointed out the most massive deer in South America (including extinct and extant) and recognized Morenelaphus as the second heaviest. The record of these large deers with huge antlers suggests the presence of natural grasslands areas and milder climatic conditions for late Pleistocene in the Brazilian Intertropical Region. Climatic and environmental changes may have driven these large deers to extinction in the Pleistocene/Holocene transition. This study reveals an unprecedented Cervidae diversity for the Brazilian Intertropical Region, emphasizes the relevance of dental features, together with antlers morphology, in taxonomic studies of Cervidae, and also highlights the importance of South American natural heritage in the retrieving of knowledge and new scientific discoveries through collection specimens. • Dental features are as significant as antlers morphology in Cervidae taxonomy. • South American low latitudes are here included in the geographic distribution of Morenelaphus during the Pleistocene. • We noticed the greatest and heaviest Cervidae ever recorded in South America. • The presence of giant deers suggests grasslands and milder climate to Brazilian Intertropical Region during the Pleistocene. • Pleistocene changes in climatic/environmental possibly influenced the extinction of giant deers. [ABSTRACT FROM AUTHOR]

The fossil record of South American cathartids, with few exceptions, is largely restricted to Late Pleistocene and Holocene sites. This contribution provides for the first time fossil records of cathartids from Uruguay. The specimens reported here include an; almost complete fibula, an incomplete furcula, and the distal end of a tibiotarsus. The; first two specimens came from Late Pleistocene beds at two localities of from Northern Uruguay, and the last one comes from Late Pleistocene-Early Holocene beds from South-western Uruguay. All the specimens were associated with several megafaunal fossil remains. The systematic assignation and paleobiological implications of these scavenger birds are here discussed. • The first record of Cathartidae from Uruguay are reported. • Fossil come from sediments assigned to Late Pleistocene and Late Pleistocene-Early Holocene ages. • The fossil materials were associated with several megafaunal fossil remains. • The systematic assignment and paleobiological implications of these scavenger birds are discussed. [ABSTRACT FROM AUTHOR]

New information about the distribution, geometry, structure, extension and facies variations of the uppermost stratigraphic sequences (particularly the Holocene) of the southern coastal plain of the Río de la Plata was obtained by using geophysical methods. This is the first study performed in the region to investigate the shallow stratigraphic characteristics through continuous geophysical surveys. Methods used were georadar (GPR), electrical resistivity tomography (ERT) and seismic surface waves (SSW), complemented with short drillings. Two transects perpendicular to the coastline were selected on the basis of the previous geological knowledge of the region and accessibility. GPR was used in order to obtain a dense sampling of the near subsoil, whereas ERT and SSW were used in parts of the transects for resolving ambiguous trajectories of the detected GPR horizons. The geophysical results were jointly interpreted, and validated and complemented by the information from the drillings. Two major geophysical horizons were identified; the lower one is located between 5 and 2 m below surface and progressively shallows inland, which represents the late Pleistocene-Holocene boundary; the upper one, located at variable depths of 2 m–0.70 m below surface, represents the base of the Holocene beach ridges system in the region. They delimit three units, the lower one corresponding to the top of the Pampean deposits, the middle one representing the basal Holocene sandy layer, and the upper one corresponding to the beach ridges systems and related inter-ridge, tidal deposits. In this way, the applied methodology allowed to determine the extension of the Holocene sedimentary sequences, the relation between the Holocene sequences and its substratum, and the spatial distribution and geometrical characteristics of partially buried beach ridges and associated inter-ridges deposits. The applied methodology and the obtained geophysical-response patterns can be useful for future investigations of other regions with similar ground characteristics. • This is the first study performed in the region to investigate the shallowstratigraphic characteristics through continuous geophysical surveys. • First work combining diverse geophysical technics in the region. • The applied geophysical methodology allowed to determine the extension of the Holocene sedimentary sequences, the relation between the Holocene sequences and its substratum, and the spatial distribution and geometrical characteristics of partially buried beach ridges and associated inter-ridges deposits. • The applied methodology and the obtained geophysical-response patterns can be useful for future investigations of other regions with similar ground characteristics. [ABSTRACT FROM AUTHOR]