Late Pleistocene Time Research Articles

Genomic analyses correspond with deep persistence of peoples of Blackfoot Confederacy from glacial times.

Mutually beneficial partnerships between genomics researchers and North American Indigenous Nations are rare yet becoming more common. Here, we present one such partnership that provides insight into the peopling of the Americas and furnishes another line of evidence that can be used to further treaty and Indigenous rights. We show that the genomics of sampled individuals from the Blackfoot Confederacy belong to a previously undescribed ancient lineage that diverged from other genomic lineages in the Americas in Late Pleistocene times. Using multiple complementary forms of knowledge, we provide a scenario for Blackfoot population history that fits with oral tradition and provides a plausible model for the evolutionary process of the peopling of the Americas.

Late Cenozoic faulting deformation of the Fanshi Basin (northern Shanxi rift, China), inferred from palaeostress analysis of mesoscale fault-slip data

AbstractThe Fanshi Basin is one of the NE–SW-striking depocentres formed along the northern segment of the fault-bounded Shanxi rift. In order to understand the crustal driving stresses that led to the basin formation and development, a palaeostress analysis of a large quantity of fault-slip data collected mainly at the boundaries of the basin was accomplished. The stress inversion of these data revealed three stress regimes. The oldest SR1 was a Neogene stress regime giving rise to a strike-slip deformation with NE–SW contraction and NW–SE extension. SR1 activated the large faults trending NNE–NE, i.e. (sub)parallel to the main strike of the Shanxi rift, as right-lateral strike-slip faults. It was subjected to the Shanxi rift before the activation of the Fanshi Basin boundary fault, i.e. the Fanshi (or Wutai) fault, as a normal fault. The next is a short-lived NE–SW extensional stress regime SR2 in early Pleistocene time, which shows the inception of the basin’s extension. A strong NW–SE to NNW–SSE extensional stress regime SR3 has governed the northern segment of the Shanxi rift since late Pleistocene time and is the present-day extension. It gave rise to the current half-graben geometry of the Fanshi Basin by activating the Fanshi (or Wutai) fault as a normal fault in the southern part of the graben. Because of the dominance of the NW–SE to NNW–SSE extension, which is perpendicular to the NE–SW extension, mutual permutations between σ3and σ2due to inherited fault patterns might have occurred while the crustal stresses in the Fanshi Basin changed from the SR1 to SR3 stress regimes.

The emergence of collective knowledge and cumulative culture in animals, humans and machines.

The emergence of collective knowledge and cumulative culture in animals, humans and machines.

The Nelson stone tool cache, North-Central Ohio, U.S.A.: Assessing its cultural affiliation

The Nelson stone tool cache was discovered in 2008 in Mount Vernon, Ohio. The cache does not include any diagnostic materials, and independent age control is unavailable. Although aspects of its 164 bifaces are suggestive of a Clovis affiliation – including the occasional occurrence of unmistakable flute scars – nearly all are in the early- to mid-stages of production, there are no definitive finished Clovis fluted points that would make it possible to assign the cache to that time period. To ascertain its cultural affiliation, we undertook a detailed qualitative and quantitative comparison of the Nelson cache bifaces with ones known to be both Clovis and post-Clovis in age. We also conducted geochemical sourcing, ochre analyses, and microwear analysis to understand the context of the cache, regardless of its age and cultural affinity. By some key measures it is consistent with Clovis caches in this region and elsewhere, but the case remains unproven. Nonetheless, if the Nelson cache is from the Clovis period, it is significant that most of its bifaces appear to be made on large flakes, in keeping with Clovis technology in the Lower Great Lakes, and an economically conservative, risk-mitigating strategy that conforms to predictions of human foragers colonizing the area in late Pleistocene times.

Phylogenetic tree of Litopterna and Perissodactyla indicates a complex early history of hoofed mammals

The Litopterna is an extinct clade of endemic South American ungulates that range from Paleocene up to late Pleistocene times. Because of their unique anatomy, litopterns are of uncertain phylogenetic affinities. However, some nineteenth century authors, considered litopterns as related to perissodactyl ungulates, a hypothesis recently sustained by molecular data. The aim of the present contribution is to include litopterns and other South American related taxa in a comprehensive phylogenetic analysis together with several extant and extinct basal perissodactyl ungulates. The analysis resulted in the nesting of litopterns and kin as successive stem-clades of crown Perissodactyla. Further, litopterns are not phylogenetically grouped with any North American basal ungulate, in agreement with some previous proposals. Presence of pan-perissodactyls in South America and India indicates that southern continents probably played an important role in the early evolution of hoofed mammals.

Testing the potential of K-feldspar pIR-IRSL and quartz ESR for dating coastal alluvial fan complexes in arid environments

Coastal alluvial fans (CAF) are important geo-archives due to their sensitivity to both tectonic activity and climatic changes. Thus, they can give key insights for geomorphic and sedimentary processes. In this study we test the potential of K-feldspar post infrared-infrared stimulated luminescence (pIR-IRSL) and quartz electron spin resonance (ESR) methods for dating alluvial fan complexes in arid environments. The existing chronological data from marine terraces that interact with CAF make the Atacama Desert in northern Chile an excellent setting for this research. Samples have been collected from alluvial, marine and aeolian sediments embedded in the CAF complexes, allowing evaluation of the different signal properties and bleaching characteristics of the pIR-IRSL and ESR signals over Late Pleistocene time scales.pIR-IRSL dose distributions of clast-rich alluvial fan samples are characterised by higher scatter and demonstrate heterogeneous bleaching, while matrix-rich alluvial fan deposits show rather homogeneous poor bleaching in the dose dispersion as indicated by a modern analogue sample. In contrast, marine and aeolian deposits are homogeneously well bleached, supported by a modern littoral sample. Following the quartz multiple centre (MC) ESR dating approach (Al and Ti centres), bleaching of the different centres prior to deposition has been achieved. While the Ti–H centre provides mostly lower doses than the Ti–Li centre, in most cases the Al centre provides the highest dose values. This pattern is consistent with their respective bleaching kinetics and suggests that the Ti centre signals most likely provide the closest estimate to the true burial dose for samples with doses >200 Gy.ESR and pIR-IRSL ages are consistent at 2σ for the marine, aeolian and clast-rich debris-flow deposits, which is in agreement with existing chronological data in this area. It appears that the mode of sediment transport on alluvial fans, either as matrix- or clast-rich flows, plays an important role in sediment bleaching. While clast-rich alluvial fan deposits are likely better bleached, we cannot exclude insufficient bleaching during matrix-rich alluvial fan flows; our dating results suggest that both pIR-IRSL and ESR dating overestimate the true burial age. The combination of pIR-IRSL and MC ESR dating can be considered as a promising tool for deciphering alluvial fan formation over (Late) Pleistocene time scales.

Late Pleistocene and Late Holocene environment and climate in the campos region of southeastern South America inferred from phytolith, diatom and geochemical data

A paleolimnological study was undertaken for a sediment core from Laguna Formosa, a subtropical lake in the northern campos inland region of Uruguay. The record encompasses a Late Pleistocene and Late Holocene interval, interrupted by a hiatus. We analyzed (1) opal phytoliths and diatoms to infer the regional environment, climate, and changes in lake trophic state, and (2) total carbon and nitrogen (TC and TN) and stable isotope data (δ13C and δ15N) to infer organic matter sources and composition. Findings indicate that, in Late Pleistocene times, a cool, semi-arid or highly seasonal climate existed, with a dominance of C3 grasslands and riparian hydrophilous shrublands while the shallow freshwater environment was characterized by benthic diatoms and littoral macrophytes. Late Holocene times were initially characterized by a temperate and humid or sub-humid climate, and dominance of grasslands and bunch grasses, while Laguna Formosa was dominated by phytoplankton. The abundance and diversity of littoral hydrophilic vegetation, and riparian forest vegetation, increased progressively over time, as a result of increased rainfall, from ca. 1800 cal yr BP and the onset of a subtropical (temperate and humid) climate by ca. 1300 cal yr BP. Such inferences are in close agreement with an earlier palynological study of Laguna Formosa, and support the paleoclimatic models for the Late Pleistocene and Late Holocene of southeastern South America.

Dawson tephra, a widespread 29‐ka marker bed, in a marine core from Patton Seamount off the Alaska Peninsula and its potential marine–terrestrial correlation

ABSTRACTA tephra layer with normal grading in the sub‐bottom depth interval 119–122 cm in marine core SO202‐27‐6 was collected on Patton Seamount in the northeast North Pacific Ocean. Based on the geochemistry of volcanic glass shards determined by a wavelength dispersive electron probe micro‐analyser and an X‐ray fluorescence analyser, this layer is correlated to the Dawson tephra, a widespread late Pleistocene time marker tephra in Alaska and the Yukon. The age of the Dawson tephra in the core is 29.03 ± 0.178 ka (1 sigma) based on a published age model. The Dawson tephra is revealed to have been deposited in the transition from marine isotope stage 3 to 2, i.e. the last stage of Heinrich Stadial 3 derived from the ice‐rafted debris signal. According to the correlation between Greenland (NGRIP ice core) and this core, the Dawson tephra occupies the record immediately before inter stadial 4 in the δ18O stratigraphy of NGRIP. The Dawson tephra on Patton Seamount includes lithic fragments, which suggests that it was deposited not only by fall‐out but also in part via another mechanism, such as icebergs from the Cordilleran ice sheet or seasonal sea ice.

An Early Upper Palaeolithic Stone Tool Assemblage from Mughr El-Hamamah, Jordan: An Interim Report

ABSTRACTMughr el-Hamamah (Jordan) Layer B contains an Early Upper Palaeolithic stone tool assemblage dating to around 39–45 kya cal b.p. This assemblage is unusual in that it samples human forager activities around the ecotone between the Transjordanian Plateau and the palaeo-lake (Lake Lisan) that filled much of the Jordan Valley during Late Pleistocene times. This paper describes that assemblage, comparing it to other Levantine Upper Palaeolithic assemblages of equivalent antiquity. The Mughr el-Hamamah Layer B assemblage appears most similar to Early Ahmarian assemblages, but it departs from typical such assemblages in ways that may reflect local conditions’ influence on human activities carried out in and near the cave. Mughr el-Hamamah raises new questions about changes in residential mobility, off-site provisioning and foraging activity, and on-site task diversity in the Early Upper Palaeolithic period.

Monsoon-induced errors in paleotemperature estimation based on leaf morphology analysis in central Japan

Models based on the relationship between leaf morphology and climate parameters of different regions have been used for paleoclimate estimation. Information from Japanese floras has been included in some of these models; however, variation in the distribution pattern of leaf margin within Japan caused by the effect of topography and East Asian Monsoon has not been reflected in these previously published leaf margin analysis models. In this study, we investigate the relationship between leaf characters and climate parameters under different climate conditions within a small geographical scale and, in doing so, improve the accuracy of leaf physiognomy-based paleoclimate reconstruction. We use the local flora in central Japan as an example to determine the distribution pattern of leaf margin (toothed and untoothed) and habit (evergreen and deciduous) characteristics under monsoon climate conditions. In areas along the Pacific Ocean (P-zone), the leaf margin and habit types correlated with the temperature parameters and growing season precipitation. The P-zone includes more toothed species than in other regions of the world obtained with published models at a given mean annual temperature. In the areas along the Sea of Japan (J-zone) with deeper snow cover during the winter, the percent of sub-canopy evergreen shrubs increases, especially at higher altitudes. No significant relationship between leaf margin characters and climate parameters was observed in this area. As heavy snow was a feature of this region since late Early Pleistocene times, paleoclimate estimation based on leaf margin of fossil assemblages younger than Early Pleistocene from these areas might be less reliable. In addition, we found that the leaf margin of woody shrub species is less sensitive to the mean annual temperature than tree species.

Variations in δ13C values of sedimentary organic matter since late Miocene time in the Indus Fan (IODP Site 1457) of the eastern Arabian Sea

AbstractA 1108.6 m long core was recovered at Site U1457 located on the Indus Fan in the Laxmi Basin of the eastern Arabian Sea during IODP Expedition 355. Shipboard examinations defined five lithologic units (I to V) of the lower Paleocene to Holocene sedimentary sequence. In this study, δ13C values of sedimentary organic matter (SOM) confirm the differentiation of the lithologic units and further divide units III and IV into two subunits (1 and 2). Based on the underlying assumption that the SOM is decided primarily by a mixture of marine and terrestrial origins, δ13CSOM values at Site U1457 provide information on the terrestrial catchment conditions since late Miocene time. Low δ13CSOM values from late Miocene to late Pleistocene times are similar (c. −22.0 ‰) for the most part, reflecting a consistent contribution of terrestrial organic matter from the catchment areas characterized by dominant C3 land plants. Significantly lower δ13CSOM values (c. −24.0 ‰) in Unit III-2 (∼8 to ∼7 Ma) might be due to a greater input of C3 terrestrial organic matter. The increase in δ13CSOM values at ∼7 Ma and the appearance of high δ13CSOM values (c. −18.0 ‰) within Unit III-1 (∼7 to ∼2 Ma) indicate that C4 biomass overwhelmed the terrestrial catchment environment as a result of enhanced terrestrial aridity in the Himalayan foreland. The three-end-member simple mixing model, estimating the relative contributions of SOM from terrestrial C3 and C4 plants and marine phytoplankton, supports our interpretation of the distribution of C3 and C4 land plants in the terrestrial catchment environment.

Tectonic reconstruction of Cyprus reveals Late Miocene continental collision of Africa and Anatolia

The extended northern continental margin of Africa is currently colliding with and under-thrusting northward below Cyprus. The age of onset of this collision is poorly constrained, but is critical if we are to quantify continental subduction and evaluate its role during spectacular recent uplift of southern Turkey from ~7 Ma to the present. Here, we reevaluate the evolution of northern Cyprus and document the modern structure of the Kyrenia fold-thrust belt in a balanced cross section for the first time, to determine the timing and amount of shortening. The belt deformed an Upper Cretaceous to Miocene stratigraphy, which was deposited onto a metamorphic basement. The fold-thrust belt was previously proposed to have formed during two stages: in Eocene and late Miocene time, based on stratigraphic and limited structural evidence. We revaluate evidence for an Eocene phase of thrusting in Kyrenia and find that 1) repetitions of Eocene and older rocks are explained by Miocene thrusting, and newly documented olistoliths were misinterpreted as pre-Miocene thrust slices 2) uplift in Eocene time was not isolated to Kyrenia but also affected northern Arabia and results from regional dynamic topography or forebulge formation. Based on kinematic constraints from a plate reconstruction, we interpret that metamorphic rocks in Kyrenia were metamorphosed by Cretaceous burial below the Troodos ophiolite and were subsequently exhumed by upper plate extension during latest Cretaceous obduction onto the African margin. The latest Cretaceous-Miocene plate boundary between Africa and the Taurides was located to the north of Kyrenia. The Kyrenia fold-thrust belt accommodated a minimum of 17.5 km of shortening as a result of ~9–6 Ma thrusting as a result of initial Africa-Taurides collision. The northern edge of African continental crust arrived below the Taurides, where it has been seismologically imaged, in late Pleistocene time and may have caused or contributed to recently recognised major Tauride uplift since ~0.5 Ma.

Mass Transport Deposits and geo-hazard assessment in the Bradano Foredeep (Southern Apennines, Ionian Sea)

Seafloor bathymetry, combined with multi-scale seismic reflection profiles, were used to describe the morphostructural setting of the Bradano Foredeep (Gulf of Taranto, northern Ionian Sea), where a submerged portion of the Southern Apennines is facing the Apulia Platform in the Calabrian Arc convergent margin. In this complex area, marine geophysical data highlight the presence of two mega-slide deposits at the shelf-slope transition, which are most likely the largest ever described in the region. These slid masses, named the Bradano Basento MegaSlide (BBMS) and Bradano Basento MegaSlide 1 (BBMS1), form a Mass Transport Deposit Complex (MTDC) affecting and eroding the topmost portion of the outer Apennines deformation front and the Apulian Foreland Ramp. It was emplaced in late Pleistocene times inside the narrow (about 10 km wide) Bradano Foredeep basin, a Plio-Pleistocene submarine trough developing at the chain front. The youngest of these deposits (BBMS1) likely predates the Last Glacial Maximum. Location of the MTDC within the subduction complex suggests that active tectonics and seismic shaking might represent the main triggering mechanisms for gravitative instability in this area, although gravitational tectonics and sediment creeping mechanisms cannot be excluded. On the other hand, size and distribution of the MTDC in the sedimentary record of the Bradano Foredeep suggest the need of re-evaluating the potential for large earthquakes/tsunamis, and more in general geological hazard related to submarine sliding masses, along the coast of this highly populated area.

Crustal-scale fluid circulation and co-seismic shallow comb-veining along the longest normal fault of the central Apennines, Italy

The extensional Val Roveto Fault, which is the longest exhumed potentially-seismogenic structure of central Apennines, Italy, is examined to constrain earthquake-related fluid circulation and fluid sources within shallow carbonate-hosted faults. The study focuses on fault-related comb and slip-parallel veins that are calcite-filled and cut through the principal surface of the Val Roveto Fault. We observe multiple crack-and-seal events characterized by several veining episodes, probably related to different slip increments along the fault plane. We show that vein calcite precipitated in Late Pleistocene time below the present-day outcrop level at a maximum depth of ∼350 m and temperatures between 32 and 64 °C from meteoric-derived fluids modified by reactions with crustal rocks and with a mantle contribution (up to ∼39%). The observed warm temperatures are not compatible with a shallow (≤∼350 m) precipitation depth, which, in this region, is dominated by circulation of cold meteoric water and/or shallow groundwater. Based on structural–geochemical data, we propose that deep-seated crust–mantle-derived warm fluids were squeezed upward during earthquakes and were hence responsible for calcite precipitation at shallow depths in co-seismic comb and slip-parallel fractures. As comb- and slip-parallel veins are rather common, particularly along seismogenic extensional faults, we suggest that further studies are necessary to test whether these veins are often of co-seismic origin. If so, they may become a unique and irreplaceable tool to unravel the seismic history of hazardous active faults.

A late Pleistocene skeleton of Rhinoceros unicornis (Mammalia, Rhinocerotidae) from western part of Thailand (Kanchanaburi Province)

A subcomplete skeleton of a rhinoceros was discovered during excavation works in Kanchanaburi Province (Thailand) in May 1991. Fossil bones were preserved in anatomical connection in a late Pleistocene clay deposit. We describe these remains and refer them to as the Indian rhinoceros Rhinoceros unicornis. This fossil skeleton is the only one of its kind discovered in Southeast Asia and allows a complete description of the skeletal morphology of this species. The metric data reveal a close skeletal morphology with extant specimens from India and Nepal. The Kanchanaburi rhinoceros specimen confirms the much broader geographic distribution of the greater one-horned rhino during late Pleistocene times. This discovery provides a useful benchmark for the study of the evolutionary stages of this species in Southeast Asia during the concerned time interval.

Impact-related microspherules in Late Pleistocene Alaskan and Yukon \u201cmuck\u201d deposits signify recurrent episodes of catastrophic emplacement

Large quantities of impact-related microspherules have been found in fine-grained sediments retained within seven out of nine, radiocarbon-dated, Late Pleistocene mammoth (Mammuthus primigenius) and bison (Bison priscus) skull fragments. The well-preserved fossils were recovered from frozen “muck” deposits (organic-rich silt) exposed within the Fairbanks and Klondike mining districts of Alaska, USA, and the Yukon Territory, Canada. In addition, elevated platinum abundances were found in sediment analysed from three out of four fossil skulls. In view of this new evidence, the mucks and their well-preserved but highly disrupted and damaged vertebrate and botanical remains are reinterpreted in part as blast deposits that resulted from several episodes of airbursts and ground/ice impacts within the northern hemisphere during Late Pleistocene time (~46–11 ka B.P.). Such a scenario might be explained by encounters with cometary debris in Earth-crossing orbits (Taurid Complex) that was generated by fragmentation of a large short-period comet within the inner Solar System.

The Guanacaste Volcanic Arc Sliver of Northwestern Costa Rica

Recent studies have shown that the Nicoya Peninsula of northwestern Costa Rica is moving northwestward ~11 mm a−1 as part of a tectonic sliver. Toward the northwest in El Salvador the northern sliver boundary is marked by a dextral strike-slip fault system active since Late Pleistocene time. To the southeast there is no consensus on what constitutes the northern boundary of the sliver, although a system of active crustal faults has been described in central Costa Rica. Here we propose that the Haciendas-Chiripa fault system serves as the northeastern boundary for the sliver and that the sliver includes most of the Guanacaste volcanic arc, herein the Guanacaste Volcanic Arc Sliver. In this paper we provide constraints on the geometry and kinematics of the boundary of the Guanacaste Volcanic Arc Sliver that are timely and essential to any models aimed at resolving the driving mechanism for sliver motion. Our results are also critical for assessing geological hazards in northwestern Costa Rica.

Quaternary deformation and stress field in the Río de la Plata Craton (Southeastern South America)

The aim of this research was to analyse the deformation in an intraplate region of southeastern South America. We analysed the motion velocities of GNSS permanent stations to characterise the stress field in the Río de la Plata Craton (RPC). To this end, a multi-year solution of the SIRGAS-CON continuous monitoring geodetic network was analysed. Seven stations in the cratonic region in the Pampean flat-slab subduction latitudes were considered. The solution encompasses the weekly solutions from January 2000 up to one day before the Maule earthquake on February 26th, 2010. The GNSS stations that produce significant results are located in Argentine territory and have a time span of at least 2 years. The stresses inferred from the strain rate tensors obtained from triangle arrays and relative displacement velocities between stations (baselines) suggest a compressive/transpressive regimen in the central-western RPC. On the basis of the GNSS velocity field, we can estimate maximum compression axes ranging from 3.5 to 5.3 nano-strain with W-E trends (90.3°-93.8°E), which differs slightly from the convergence vector between the Nazca and South American plates (ENE/78°E). This result strongly suggests the influence on the South America mid-plate from far-field stresses generated in the plate margins and the rotation of the maximum compression axes due to the growing influence eastward from the Mid-Atlantic ridge push. Satellite gravimetric data allow us to interpret the presence of upper crustal structures, which match surface morphostructural features. It is reasonable to think that the structures concentrate the recent deformation. The geometry of the subsurface structures inferred appears to favour reverse slips, compatible with the stress field interpreted from geodetic data.Regional wetland layers interpreted to be planar geomorphic markers, currently situated at elevations higher than the maximum sea levels reached over the Quaternary, can be interpreted as evidence of deformation and regional uplift. The compressive stresses appear to have substantial control over the uplift in the wide lowland areas of the Chaco-Parana intracratonic basin. The geomorphologic analysis suggests lineal uplift rates from 0.025 to 0.050 mm yr−1 for the central RPC in the Quaternary time scale and 0.1–0.35 mm yr−1 for the western RPC in the Late Pleistocene time scale.Although geodetic data are not conclusive evidence of seismic hazards, the confluence of geodetic and geologic data allows us to presume that deformation energy is being accumulated in the main fault systems.

First Record of Puma concolor (Mammalia, Felidae) in the Early-Middle Pleistocene of South America

Felidae is represented in South America by approximately ten species, belonging to three main phylogenetic lineages: the Ocelot lineage, the Puma lineage, and the Panthera lineage. Pumas (Puma concolor) and jaguarundis (Puma yagouaroundi), together with the African cheetahs (Acinonyx jubatus), compose the puma lineage. Paleontological knowledge about Puma concolor in North and South America is mainly restricted to the late Pleistocene and Holocene. In this contribution, we describe the first skull of Puma concolor from the early-middle Pleistocene (Ensenadan Stage/Age) of the costal cliffs of Santa Elena Creek, north of Mar del Plata city (37°52′03″S - 57°30′49″W, Buenos Aires province, Argentina). The remains (MMP 1476-M) come from stratigraphic Level 2 of the Miramar Formation and were found by one the authors (AD). The specimen described here was compared with a large number of recent and fossils individuals. The new material is represented by a partial skull and mandible with complete dental series. The anatomical analysis demonstrates that MMP 1476-M perfectly matches with the morphology of living puma specimens. The associated fauna (e.g., Protocyon scagliarum, Theriodictis platensis, Mesotherium cristatum) and paleomagnetic data support an upper Ensenadan Stage/Age. Previously reported Ensenadan pumas lack features diagnostic of Puma concolor. Thus, here we report the first unequivocal record of Puma concolor prior to late Pleistocene times in South America. Previous hypotheses of the South American origin of Puma concolor are in congruence with the fossil record of North, Central, and South America.

Dietary responses of Sahul (Pleistocene Australia–New Guinea) megafauna to climate and environmental change

AbstractThroughout the late Quaternary, the Sahul (Pleistocene Australia–New Guinea) vertebrate fauna was dominated by a diversity of large mammals, birds, and reptiles, commonly referred to as megafauna. Since ca. 450–400Ka, approximately 88 species disappeared in Sahul, including kangaroos exceeding 200kg in size, wombat-like animals the size of hippopotamuses, flightless birds, and giant monitor lizards that were likely venomous. Ongoing debates over the primary cause of these extinctions have typically favored climate change or human activities. Improving our understanding of the population biology of extinct megafauna as more refined paleoenvironmental data sets become available will assist in identifying their potential vulnerabilities. Here, we apply a multiproxy approach to analyze fossil teeth from deposits dated to the middle and late Pleistocene at Cuddie Springs in southeastern Australia, assessing relative aridity via oxygen isotopes as well as vegetation and megafaunal diets using both carbon isotopes and dental microwear texture analyses. We report that the Cuddie Springs middle Pleistocene fauna was largely dominated by browsers, including consumers of C4shrubs, but that by late Pleistocene times the C4dietary component was markedly reduced. Our results suggest dietary restriction in more arid conditions. These dietary shifts are consistent with other independently derived isotopic data from eggshells and wombat teeth that also suggest a reduction in C4vegetation after ~45 Ka in southeastern Australia, coincident with increasing aridification through the middle to late Pleistocene. Understanding the ecology of extinct species is important in clarifying the primary drivers of faunal extinction in Sahul. The results presented here highlight the potential impacts of aridification on marsupial megafauna. The trend to increasingly arid conditions through the middle to late Pleistocene (as identified in other paleoenvironmental records and now also observed, in part, in the Cuddie Springs sequence) may have stressed the most vulnerable animals, perhaps accelerating the decline of late Pleistocene megafauna in Australia.